// Copyright 2025 Envoy Project Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";

package envoy.config.route.v3;

import "envoy/config/core/v3/base.proto";
import "envoy/config/core/v3/extension.proto";
import "envoy/config/core/v3/proxy_protocol.proto";
import "envoy/type/matcher/v3/filter_state.proto";
import "envoy/type/matcher/v3/metadata.proto";
import "envoy/type/matcher/v3/regex.proto";
import "envoy/type/matcher/v3/string.proto";
import "envoy/type/metadata/v3/metadata.proto";
import "envoy/type/tracing/v3/custom_tag.proto";
import "envoy/type/v3/percent.proto";
import "envoy/type/v3/range.proto";

import "google/protobuf/any.proto";
import "google/protobuf/duration.proto";
import "google/protobuf/wrappers.proto";

import "xds/type/matcher/v3/matcher.proto";

import "envoy/annotations/deprecation.proto";
import "udpa/annotations/migrate.proto";
import "udpa/annotations/status.proto";
import "udpa/annotations/versioning.proto";
import "validate/validate.proto";

option java_package = "io.envoyproxy.envoy.config.route.v3";
option java_outer_classname = "RouteComponentsProto";
option java_multiple_files = true;
option go_package = "github.com/envoyproxy/go-control-plane/envoy/config/route/v3;routev3";
option (udpa.annotations.file_status).package_version_status = ACTIVE;

// [#protodoc-title: HTTP route components]
// * Routing :ref:`architecture overview <arch_overview_http_routing>`
// * HTTP :ref:`router filter <config_http_filters_router>`

// The top level element in the routing configuration is a virtual host. Each virtual host has
// a logical name as well as a set of domains that get routed to it based on the incoming request's
// host header. This allows a single listener to service multiple top level domain path trees. Once
// a virtual host is selected based on the domain, the routes are processed in order to see which
// upstream cluster to route to or whether to perform a redirect.
// [#next-free-field: 25]
message VirtualHost {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.VirtualHost";

  enum TlsRequirementType {
    // No TLS requirement for the virtual host.
    NONE = 0;

    // External requests must use TLS. If a request is external and it is not
    // using TLS, a 301 redirect will be sent telling the client to use HTTPS.
    EXTERNAL_ONLY = 1;

    // All requests must use TLS. If a request is not using TLS, a 301 redirect
    // will be sent telling the client to use HTTPS.
    ALL = 2;
  }

  reserved 9, 12;

  reserved "per_filter_config";

  // The logical name of the virtual host. This is used when emitting certain
  // statistics but is not relevant for routing.
  string name = 1 [(validate.rules).string = {min_len: 1}];

  // A list of domains (host/authority header) that will be matched to this
  // virtual host. Wildcard hosts are supported in the suffix or prefix form.
  //
  // Domain search order:
  //  1. Exact domain names: ``www.foo.com``.
  //  2. Suffix domain wildcards: ``*.foo.com`` or ``*-bar.foo.com``.
  //  3. Prefix domain wildcards: ``foo.*`` or ``foo-*``.
  //  4. Special wildcard ``*`` matching any domain.
  //
  // .. note::
  //
  //   The wildcard will not match the empty string.
  //   e.g. ``*-bar.foo.com`` will match ``baz-bar.foo.com`` but not ``-bar.foo.com``.
  //   The longest wildcards match first.
  //   Only a single virtual host in the entire route configuration can match on ``*``. A domain
  //   must be unique across all virtual hosts or the config will fail to load.
  //
  // Domains cannot contain control characters. This is validated by the well_known_regex HTTP_HEADER_VALUE.
  repeated string domains = 2 [(validate.rules).repeated = {
    min_items: 1
    items {string {well_known_regex: HTTP_HEADER_VALUE strict: false}}
  }];

  // The list of routes that will be matched, in order, for incoming requests.
  // The first route that matches will be used.
  // Only one of this and ``matcher`` can be specified.
  repeated Route routes = 3 [(udpa.annotations.field_migrate).oneof_promotion = "route_selection"];

  // The match tree to use when resolving route actions for incoming requests. Only one of this and ``routes``
  // can be specified.
  xds.type.matcher.v3.Matcher matcher = 21
      [(udpa.annotations.field_migrate).oneof_promotion = "route_selection"];

  // Specifies the type of TLS enforcement the virtual host expects. If this option is not
  // specified, there is no TLS requirement for the virtual host.
  TlsRequirementType require_tls = 4 [(validate.rules).enum = {defined_only: true}];

  // A list of virtual clusters defined for this virtual host. Virtual clusters
  // are used for additional statistics gathering.
  repeated VirtualCluster virtual_clusters = 5;

  // Specifies a set of rate limit configurations that will be applied to the
  // virtual host.
  repeated RateLimit rate_limits = 6;

  // Specifies a list of HTTP headers that should be added to each request
  // handled by this virtual host. Headers specified at this level are applied
  // after headers from enclosed :ref:`envoy_v3_api_msg_config.route.v3.Route` and before headers from the
  // enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including
  // details on header value syntax, see the documentation on :ref:`custom request headers
  // <config_http_conn_man_headers_custom_request_headers>`.
  repeated core.v3.HeaderValueOption request_headers_to_add = 7
      [(validate.rules).repeated = {max_items: 1000}];

  // Specifies a list of HTTP headers that should be removed from each request
  // handled by this virtual host.
  repeated string request_headers_to_remove = 13 [(validate.rules).repeated = {
    items {string {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}}
  }];

  // Specifies a list of HTTP headers that should be added to each response
  // handled by this virtual host. Headers specified at this level are applied
  // after headers from enclosed :ref:`envoy_v3_api_msg_config.route.v3.Route` and before headers from the
  // enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including
  // details on header value syntax, see the documentation on :ref:`custom request headers
  // <config_http_conn_man_headers_custom_request_headers>`.
  repeated core.v3.HeaderValueOption response_headers_to_add = 10
      [(validate.rules).repeated = {max_items: 1000}];

  // Specifies a list of HTTP headers that should be removed from each response
  // handled by this virtual host.
  repeated string response_headers_to_remove = 11 [(validate.rules).repeated = {
    items {string {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}}
  }];

  // Indicates that the virtual host has a CORS policy. This field is ignored if related cors policy is
  // found in the
  // :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>`.
  //
  // .. attention::
  //
  //   This option has been deprecated. Please use
  //   :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>`
  //   to configure the CORS HTTP filter.
  CorsPolicy cors = 8 [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // This field can be used to provide virtual host level per filter config. The key should match the
  // :ref:`filter config name
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpFilter.name>`.
  // See :ref:`Http filter route specific config <arch_overview_http_filters_per_filter_config>`
  // for details.
  // [#comment: An entry's value may be wrapped in a
  // :ref:`FilterConfig<envoy_v3_api_msg_config.route.v3.FilterConfig>`
  // message to specify additional options.]
  map<string, google.protobuf.Any> typed_per_filter_config = 15;

  // Decides whether the :ref:`x-envoy-attempt-count
  // <config_http_filters_router_x-envoy-attempt-count>` header should be included
  // in the upstream request. Setting this option will cause it to override any existing header
  // value, so in the case of two Envoys on the request path with this option enabled, the upstream
  // will see the attempt count as perceived by the second Envoy. Defaults to false.
  // This header is unaffected by the
  // :ref:`suppress_envoy_headers
  // <envoy_v3_api_field_extensions.filters.http.router.v3.Router.suppress_envoy_headers>` flag.
  //
  // [#next-major-version: rename to include_attempt_count_in_request.]
  bool include_request_attempt_count = 14;

  // Decides whether the :ref:`x-envoy-attempt-count
  // <config_http_filters_router_x-envoy-attempt-count>` header should be included
  // in the downstream response. Setting this option will cause the router to override any existing header
  // value, so in the case of two Envoys on the request path with this option enabled, the downstream
  // will see the attempt count as perceived by the Envoy closest upstream from itself. Defaults to false.
  // This header is unaffected by the
  // :ref:`suppress_envoy_headers
  // <envoy_v3_api_field_extensions.filters.http.router.v3.Router.suppress_envoy_headers>` flag.
  bool include_attempt_count_in_response = 19;

  // Indicates the retry policy for all routes in this virtual host. Note that setting a
  // route level entry will take precedence over this config and it'll be treated
  // independently (e.g.: values are not inherited).
  RetryPolicy retry_policy = 16;

  // [#not-implemented-hide:]
  // Specifies the configuration for retry policy extension. Note that setting a route level entry
  // will take precedence over this config and it'll be treated independently (e.g.: values are not
  // inherited). :ref:`Retry policy <envoy_v3_api_field_config.route.v3.VirtualHost.retry_policy>` should not be
  // set if this field is used.
  google.protobuf.Any retry_policy_typed_config = 20;

  // Indicates the hedge policy for all routes in this virtual host. Note that setting a
  // route level entry will take precedence over this config and it'll be treated
  // independently (e.g.: values are not inherited).
  HedgePolicy hedge_policy = 17;

  // Decides whether to include the :ref:`x-envoy-is-timeout-retry <config_http_filters_router_x-envoy-is-timeout-retry>`
  // request header in retries initiated by per try timeouts.
  bool include_is_timeout_retry_header = 23;

  // The maximum bytes which will be buffered for retries and shadowing.
  // If set and a route-specific limit is not set, the bytes actually buffered will be the minimum
  // value of this and the listener per_connection_buffer_limit_bytes.
  google.protobuf.UInt32Value per_request_buffer_limit_bytes = 18;

  // Specify a set of default request mirroring policies for every route under this virtual host.
  // It takes precedence over the route config mirror policy entirely.
  // That is, policies are not merged, the most specific non-empty one becomes the mirror policies.
  repeated RouteAction.RequestMirrorPolicy request_mirror_policies = 22;

  // The metadata field can be used to provide additional information
  // about the virtual host. It can be used for configuration, stats, and logging.
  // The metadata should go under the filter namespace that will need it.
  // For instance, if the metadata is intended for the Router filter,
  // the filter name should be specified as ``envoy.filters.http.router``.
  core.v3.Metadata metadata = 24;
}

// A filter-defined action type.
message FilterAction {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.FilterAction";

  google.protobuf.Any action = 1;
}

// This can be used in route matcher :ref:`VirtualHost.matcher <envoy_v3_api_field_config.route.v3.VirtualHost.matcher>`.
// When the matcher matches, routes will be matched and run.
message RouteList {
  // The list of routes that will be matched and run, in order. The first route that matches will be used.
  repeated Route routes = 1;
}

// A route is both a specification of how to match a request as well as an indication of what to do
// next (e.g., redirect, forward, rewrite, etc.).
//
// .. attention::
//
//   Envoy supports routing on HTTP method via :ref:`header matching
//   <envoy_v3_api_msg_config.route.v3.HeaderMatcher>`.
// [#next-free-field: 20]
message Route {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.Route";

  reserved 6, 8;

  reserved "per_filter_config";

  // Name for the route.
  string name = 14;

  // Route matching parameters.
  RouteMatch match = 1 [(validate.rules).message = {required: true}];

  oneof action {
    option (validate.required) = true;

    // Route request to some upstream cluster.
    RouteAction route = 2;

    // Return a redirect.
    RedirectAction redirect = 3;

    // Return an arbitrary HTTP response directly, without proxying.
    DirectResponseAction direct_response = 7;

    // [#not-implemented-hide:]
    // A filter-defined action (e.g., it could dynamically generate the RouteAction).
    // [#comment: TODO(samflattery): Remove cleanup in route_fuzz_test.cc when
    // implemented]
    FilterAction filter_action = 17;

    // [#not-implemented-hide:]
    // An action used when the route will generate a response directly,
    // without forwarding to an upstream host. This will be used in non-proxy
    // xDS clients like the gRPC server. It could also be used in the future
    // in Envoy for a filter that directly generates responses for requests.
    NonForwardingAction non_forwarding_action = 18;
  }

  // The Metadata field can be used to provide additional information
  // about the route. It can be used for configuration, stats, and logging.
  // The metadata should go under the filter namespace that will need it.
  // For instance, if the metadata is intended for the Router filter,
  // the filter name should be specified as ``envoy.filters.http.router``.
  core.v3.Metadata metadata = 4;

  // Decorator for the matched route.
  Decorator decorator = 5;

  // This field can be used to provide route specific per filter config. The key should match the
  // :ref:`filter config name
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpFilter.name>`.
  // See :ref:`Http filter route specific config <arch_overview_http_filters_per_filter_config>`
  // for details.
  // [#comment: An entry's value may be wrapped in a
  // :ref:`FilterConfig<envoy_v3_api_msg_config.route.v3.FilterConfig>`
  // message to specify additional options.]
  map<string, google.protobuf.Any> typed_per_filter_config = 13;

  // Specifies a set of headers that will be added to requests matching this
  // route. Headers specified at this level are applied before headers from the
  // enclosing :ref:`envoy_v3_api_msg_config.route.v3.VirtualHost` and
  // :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including details on
  // header value syntax, see the documentation on :ref:`custom request headers
  // <config_http_conn_man_headers_custom_request_headers>`.
  repeated core.v3.HeaderValueOption request_headers_to_add = 9
      [(validate.rules).repeated = {max_items: 1000}];

  // Specifies a list of HTTP headers that should be removed from each request
  // matching this route.
  repeated string request_headers_to_remove = 12 [(validate.rules).repeated = {
    items {string {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}}
  }];

  // Specifies a set of headers that will be added to responses to requests
  // matching this route. Headers specified at this level are applied before
  // headers from the enclosing :ref:`envoy_v3_api_msg_config.route.v3.VirtualHost` and
  // :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including
  // details on header value syntax, see the documentation on
  // :ref:`custom request headers <config_http_conn_man_headers_custom_request_headers>`.
  repeated core.v3.HeaderValueOption response_headers_to_add = 10
      [(validate.rules).repeated = {max_items: 1000}];

  // Specifies a list of HTTP headers that should be removed from each response
  // to requests matching this route.
  repeated string response_headers_to_remove = 11 [(validate.rules).repeated = {
    items {string {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}}
  }];

  // Presence of the object defines whether the connection manager's tracing configuration
  // is overridden by this route specific instance.
  Tracing tracing = 15;

  // The maximum bytes which will be buffered for retries and shadowing.
  // If set, the bytes actually buffered will be the minimum value of this and the
  // listener per_connection_buffer_limit_bytes.
  google.protobuf.UInt32Value per_request_buffer_limit_bytes = 16;

  // The human readable prefix to use when emitting statistics for this endpoint.
  // The statistics are rooted at vhost.<virtual host name>.route.<stat_prefix>.
  // This should be set for highly critical
  // endpoints that one wishes to get “per-route” statistics on.
  // If not set, endpoint statistics are not generated.
  //
  // The emitted statistics are the same as those documented for :ref:`virtual clusters <config_http_filters_router_vcluster_stats>`.
  //
  // .. warning::
  //
  //    We do not recommend setting up a stat prefix for
  //    every application endpoint. This is both not easily maintainable and
  //    statistics use a non-trivial amount of memory(approximately 1KiB per route).
  string stat_prefix = 19;
}

// Compared to the :ref:`cluster <envoy_v3_api_field_config.route.v3.RouteAction.cluster>` field that specifies a
// single upstream cluster as the target of a request, the :ref:`weighted_clusters
// <envoy_v3_api_field_config.route.v3.RouteAction.weighted_clusters>` option allows for specification of
// multiple upstream clusters along with weights that indicate the percentage of
// traffic to be forwarded to each cluster. The router selects an upstream cluster based on the
// weights.
message WeightedCluster {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.WeightedCluster";

  // [#next-free-field: 13]
  message ClusterWeight {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.WeightedCluster.ClusterWeight";

    reserved 7, 8;

    reserved "per_filter_config";

    // Only one of ``name`` and ``cluster_header`` may be specified.
    // [#next-major-version: Need to add back the validation rule: (validate.rules).string = {min_len: 1}]
    // Name of the upstream cluster. The cluster must exist in the
    // :ref:`cluster manager configuration <config_cluster_manager>`.
    string name = 1 [(udpa.annotations.field_migrate).oneof_promotion = "cluster_specifier"];

    // Only one of ``name`` and ``cluster_header`` may be specified.
    // [#next-major-version: Need to add back the validation rule: (validate.rules).string = {min_len: 1 }]
    // Envoy will determine the cluster to route to by reading the value of the
    // HTTP header named by cluster_header from the request headers. If the
    // header is not found or the referenced cluster does not exist, Envoy will
    // return a 404 response.
    //
    // .. attention::
    //
    //   Internally, Envoy always uses the HTTP/2 ``:authority`` header to represent the HTTP/1
    //   ``Host`` header. Thus, if attempting to match on ``Host``, match on ``:authority`` instead.
    //
    // .. note::
    //
    //   If the header appears multiple times only the first value is used.
    string cluster_header = 12 [
      (validate.rules).string = {well_known_regex: HTTP_HEADER_NAME strict: false},
      (udpa.annotations.field_migrate).oneof_promotion = "cluster_specifier"
    ];

    // The weight of the cluster. This value is relative to the other clusters'
    // weights. When a request matches the route, the choice of an upstream cluster
    // is determined by its weight. The sum of weights across all
    // entries in the clusters array must be greater than 0, and must not exceed
    // uint32_t maximal value (4294967295).
    google.protobuf.UInt32Value weight = 2;

    // Optional endpoint metadata match criteria used by the subset load balancer. Only endpoints in
    // the upstream cluster with metadata matching what is set in this field will be considered for
    // load balancing. Note that this will be merged with what's provided in
    // :ref:`RouteAction.metadata_match <envoy_v3_api_field_config.route.v3.RouteAction.metadata_match>`, with
    // values here taking precedence. The filter name should be specified as ``envoy.lb``.
    core.v3.Metadata metadata_match = 3;

    // Specifies a list of headers to be added to requests when this cluster is selected
    // through the enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteAction`.
    // Headers specified at this level are applied before headers from the enclosing
    // :ref:`envoy_v3_api_msg_config.route.v3.Route`, :ref:`envoy_v3_api_msg_config.route.v3.VirtualHost`, and
    // :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including details on
    // header value syntax, see the documentation on :ref:`custom request headers
    // <config_http_conn_man_headers_custom_request_headers>`.
    repeated core.v3.HeaderValueOption request_headers_to_add = 4
        [(validate.rules).repeated = {max_items: 1000}];

    // Specifies a list of HTTP headers that should be removed from each request when
    // this cluster is selected through the enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteAction`.
    repeated string request_headers_to_remove = 9 [(validate.rules).repeated = {
      items {string {well_known_regex: HTTP_HEADER_NAME strict: false}}
    }];

    // Specifies a list of headers to be added to responses when this cluster is selected
    // through the enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteAction`.
    // Headers specified at this level are applied before headers from the enclosing
    // :ref:`envoy_v3_api_msg_config.route.v3.Route`, :ref:`envoy_v3_api_msg_config.route.v3.VirtualHost`, and
    // :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration`. For more information, including details on
    // header value syntax, see the documentation on :ref:`custom request headers
    // <config_http_conn_man_headers_custom_request_headers>`.
    repeated core.v3.HeaderValueOption response_headers_to_add = 5
        [(validate.rules).repeated = {max_items: 1000}];

    // Specifies a list of headers to be removed from responses when this cluster is selected
    // through the enclosing :ref:`envoy_v3_api_msg_config.route.v3.RouteAction`.
    repeated string response_headers_to_remove = 6 [(validate.rules).repeated = {
      items {string {well_known_regex: HTTP_HEADER_NAME strict: false}}
    }];

    // This field can be used to provide weighted cluster specific per filter config. The key should match the
    // :ref:`filter config name
    // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpFilter.name>`.
    // See :ref:`Http filter route specific config <arch_overview_http_filters_per_filter_config>`
    // for details.
    // [#comment: An entry's value may be wrapped in a
    // :ref:`FilterConfig<envoy_v3_api_msg_config.route.v3.FilterConfig>`
    // message to specify additional options.]
    map<string, google.protobuf.Any> typed_per_filter_config = 10;

    oneof host_rewrite_specifier {
      // Indicates that during forwarding, the host header will be swapped with
      // this value.
      string host_rewrite_literal = 11
          [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];
    }
  }

  // Specifies one or more upstream clusters associated with the route.
  repeated ClusterWeight clusters = 1 [(validate.rules).repeated = {min_items: 1}];

  // Specifies the total weight across all clusters. The sum of all cluster weights must equal this
  // value, if this is greater than 0.
  // This field is now deprecated, and the client will use the sum of all
  // cluster weights. It is up to the management server to supply the correct weights.
  google.protobuf.UInt32Value total_weight = 3
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // Specifies the runtime key prefix that should be used to construct the
  // runtime keys associated with each cluster. When the ``runtime_key_prefix`` is
  // specified, the router will look for weights associated with each upstream
  // cluster under the key ``runtime_key_prefix`` + ``.`` + ``cluster[i].name`` where
  // ``cluster[i]`` denotes an entry in the clusters array field. If the runtime
  // key for the cluster does not exist, the value specified in the
  // configuration file will be used as the default weight. See the :ref:`runtime documentation
  // <operations_runtime>` for how key names map to the underlying implementation.
  string runtime_key_prefix = 2;

  oneof random_value_specifier {
    // Specifies the header name that is used to look up the random value passed in the request header.
    // This is used to ensure consistent cluster picking across multiple proxy levels for weighted traffic.
    // If header is not present or invalid, Envoy will fall back to use the internally generated random value.
    // This header is expected to be single-valued header as we only want to have one selected value throughout
    // the process for the consistency. And the value is a unsigned number between 0 and UINT64_MAX.
    string header_name = 4
        [(validate.rules).string = {well_known_regex: HTTP_HEADER_NAME strict: false}];
  }
}

// Configuration for a cluster specifier plugin.
message ClusterSpecifierPlugin {
  // The name of the plugin and its opaque configuration.
  //
  // [#extension-category: envoy.router.cluster_specifier_plugin]
  core.v3.TypedExtensionConfig extension = 1 [(validate.rules).message = {required: true}];

  // If is_optional is not set or is set to false and the plugin defined by this message is not a
  // supported type, the containing resource is NACKed. If is_optional is set to true, the resource
  // would not be NACKed for this reason. In this case, routes referencing this plugin's name would
  // not be treated as an illegal configuration, but would result in a failure if the route is
  // selected.
  bool is_optional = 2;
}

// [#next-free-field: 17]
message RouteMatch {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.RouteMatch";

  message GrpcRouteMatchOptions {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RouteMatch.GrpcRouteMatchOptions";
  }

  message TlsContextMatchOptions {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RouteMatch.TlsContextMatchOptions";

    // If specified, the route will match against whether or not a certificate is presented.
    // If not specified, certificate presentation status (true or false) will not be considered when route matching.
    google.protobuf.BoolValue presented = 1;

    // If specified, the route will match against whether or not a certificate is validated.
    // If not specified, certificate validation status (true or false) will not be considered when route matching.
    //
    // .. warning::
    //
    //    Client certificate validation is not currently performed upon TLS session resumption. For
    //    a resumed TLS session the route will match only when ``validated`` is false, regardless of
    //    whether the client TLS certificate is valid.
    //
    //    The only known workaround for this issue is to disable TLS session resumption entirely, by
    //    setting both :ref:`disable_stateless_session_resumption <envoy_v3_api_field_extensions.transport_sockets.tls.v3.DownstreamTlsContext.disable_stateless_session_resumption>`
    //    and :ref:`disable_stateful_session_resumption <envoy_v3_api_field_extensions.transport_sockets.tls.v3.DownstreamTlsContext.disable_stateful_session_resumption>` on the DownstreamTlsContext.
    google.protobuf.BoolValue validated = 2;
  }

  // An extensible message for matching CONNECT or CONNECT-UDP requests.
  message ConnectMatcher {
  }

  reserved 5, 3;

  reserved "regex";

  oneof path_specifier {
    option (validate.required) = true;

    // If specified, the route is a prefix rule meaning that the prefix must
    // match the beginning of the ``:path`` header.
    string prefix = 1;

    // If specified, the route is an exact path rule meaning that the path must
    // exactly match the ``:path`` header once the query string is removed.
    string path = 2;

    // If specified, the route is a regular expression rule meaning that the
    // regex must match the ``:path`` header once the query string is removed. The entire path
    // (without the query string) must match the regex. The rule will not match if only a
    // subsequence of the ``:path`` header matches the regex.
    //
    // [#next-major-version: In the v3 API we should redo how path specification works such
    // that we utilize StringMatcher, and additionally have consistent options around whether we
    // strip query strings, do a case sensitive match, etc. In the interim it will be too disruptive
    // to deprecate the existing options. We should even consider whether we want to do away with
    // path_specifier entirely and just rely on a set of header matchers which can already match
    // on :path, etc. The issue with that is it is unclear how to generically deal with query string
    // stripping. This needs more thought.]
    type.matcher.v3.RegexMatcher safe_regex = 10 [(validate.rules).message = {required: true}];

    // If this is used as the matcher, the matcher will only match CONNECT or CONNECT-UDP requests.
    // Note that this will not match other Extended CONNECT requests (WebSocket and the like) as
    // they are normalized in Envoy as HTTP/1.1 style upgrades.
    // This is the only way to match CONNECT requests for HTTP/1.1. For HTTP/2 and HTTP/3,
    // where Extended CONNECT requests may have a path, the path matchers will work if
    // there is a path present.
    // Note that CONNECT support is currently considered alpha in Envoy.
    // [#comment: TODO(htuch): Replace the above comment with an alpha tag.]
    ConnectMatcher connect_matcher = 12;

    // If specified, the route is a path-separated prefix rule meaning that the
    // ``:path`` header (without the query string) must either exactly match the
    // ``path_separated_prefix`` or have it as a prefix, followed by ``/``
    //
    // For example, ``/api/dev`` would match
    // ``/api/dev``, ``/api/dev/``, ``/api/dev/v1``, and ``/api/dev?param=true``
    // but would not match ``/api/developer``
    //
    // Expect the value to not contain ``?`` or ``#`` and not to end in ``/``
    string path_separated_prefix = 14 [(validate.rules).string = {pattern: "^[^?#]+[^?#/]$"}];

    // [#extension-category: envoy.path.match]
    core.v3.TypedExtensionConfig path_match_policy = 15;
  }

  // Indicates that prefix/path matching should be case sensitive. The default
  // is true. Ignored for safe_regex matching.
  google.protobuf.BoolValue case_sensitive = 4;

  // Indicates that the route should additionally match on a runtime key. Every time the route
  // is considered for a match, it must also fall under the percentage of matches indicated by
  // this field. For some fraction N/D, a random number in the range [0,D) is selected. If the
  // number is <= the value of the numerator N, or if the key is not present, the default
  // value, the router continues to evaluate the remaining match criteria. A runtime_fraction
  // route configuration can be used to roll out route changes in a gradual manner without full
  // code/config deploys. Refer to the :ref:`traffic shifting
  // <config_http_conn_man_route_table_traffic_splitting_shift>` docs for additional documentation.
  //
  // .. note::
  //
  //    Parsing this field is implemented such that the runtime key's data may be represented
  //    as a FractionalPercent proto represented as JSON/YAML and may also be represented as an
  //    integer with the assumption that the value is an integral percentage out of 100. For
  //    instance, a runtime key lookup returning the value "42" would parse as a FractionalPercent
  //    whose numerator is 42 and denominator is HUNDRED. This preserves legacy semantics.
  core.v3.RuntimeFractionalPercent runtime_fraction = 9;

  // Specifies a set of headers that the route should match on. The router will
  // check the request’s headers against all the specified headers in the route
  // config. A match will happen if all the headers in the route are present in
  // the request with the same values (or based on presence if the value field
  // is not in the config).
  repeated HeaderMatcher headers = 6;

  // Specifies a set of URL query parameters on which the route should
  // match. The router will check the query string from the ``path`` header
  // against all the specified query parameters. If the number of specified
  // query parameters is nonzero, they all must match the ``path`` header's
  // query string for a match to occur. In the event query parameters are
  // repeated, only the first value for each key will be considered.
  //
  // .. note::
  //
  //    If query parameters are used to pass request message fields when
  //    `grpc_json_transcoder <https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/grpc_json_transcoder_filter>`_
  //    is used, the transcoded message fields maybe different. The query parameters are
  //    url encoded, but the message fields are not. For example, if a query
  //    parameter is "foo%20bar", the message field will be "foo bar".
  repeated QueryParameterMatcher query_parameters = 7;

  // If specified, only gRPC requests will be matched. The router will check
  // that the content-type header has a application/grpc or one of the various
  // application/grpc+ values.
  GrpcRouteMatchOptions grpc = 8;

  // If specified, the client tls context will be matched against the defined
  // match options.
  //
  // [#next-major-version: unify with RBAC]
  TlsContextMatchOptions tls_context = 11;

  // Specifies a set of dynamic metadata matchers on which the route should match.
  // The router will check the dynamic metadata against all the specified dynamic metadata matchers.
  // If the number of specified dynamic metadata matchers is nonzero, they all must match the
  // dynamic metadata for a match to occur.
  repeated type.matcher.v3.MetadataMatcher dynamic_metadata = 13;

  // Specifies a set of filter state matchers on which the route should match.
  // The router will check the filter state against all the specified filter state matchers.
  // If the number of specified filter state matchers is nonzero, they all must match the
  // filter state for a match to occur.
  repeated type.matcher.v3.FilterStateMatcher filter_state = 16;
}

// Cors policy configuration.
//
// .. attention::
//
//   This message has been deprecated. Please use
//   :ref:`CorsPolicy in filter extension <envoy_v3_api_msg_extensions.filters.http.cors.v3.CorsPolicy>`
//   as as alternative.
//
// [#next-free-field: 14]
message CorsPolicy {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.CorsPolicy";

  reserved 1, 8, 7;

  reserved "allow_origin", "allow_origin_regex", "enabled";

  // Specifies string patterns that match allowed origins. An origin is allowed if any of the
  // string matchers match.
  repeated type.matcher.v3.StringMatcher allow_origin_string_match = 11;

  // Specifies the content for the ``access-control-allow-methods`` header.
  string allow_methods = 2;

  // Specifies the content for the ``access-control-allow-headers`` header.
  string allow_headers = 3;

  // Specifies the content for the ``access-control-expose-headers`` header.
  string expose_headers = 4;

  // Specifies the content for the ``access-control-max-age`` header.
  string max_age = 5;

  // Specifies whether the resource allows credentials.
  google.protobuf.BoolValue allow_credentials = 6;

  oneof enabled_specifier {
    // Specifies the % of requests for which the CORS filter is enabled.
    //
    // If neither ``enabled``, ``filter_enabled``, nor ``shadow_enabled`` are specified, the CORS
    // filter will be enabled for 100% of the requests.
    //
    // If :ref:`runtime_key <envoy_v3_api_field_config.core.v3.RuntimeFractionalPercent.runtime_key>` is
    // specified, Envoy will lookup the runtime key to get the percentage of requests to filter.
    core.v3.RuntimeFractionalPercent filter_enabled = 9;
  }

  // Specifies the % of requests for which the CORS policies will be evaluated and tracked, but not
  // enforced.
  //
  // This field is intended to be used when ``filter_enabled`` and ``enabled`` are off. One of those
  // fields have to explicitly disable the filter in order for this setting to take effect.
  //
  // If :ref:`runtime_key <envoy_v3_api_field_config.core.v3.RuntimeFractionalPercent.runtime_key>` is specified,
  // Envoy will lookup the runtime key to get the percentage of requests for which it will evaluate
  // and track the request's ``Origin`` to determine if it's valid but will not enforce any policies.
  core.v3.RuntimeFractionalPercent shadow_enabled = 10;

  // Specify whether allow requests whose target server's IP address is more private than that from
  // which the request initiator was fetched.
  //
  // More details refer to https://developer.chrome.com/blog/private-network-access-preflight.
  google.protobuf.BoolValue allow_private_network_access = 12;

  // Specifies if preflight requests not matching the configured allowed origin should be forwarded
  // to the upstream. Default is true.
  google.protobuf.BoolValue forward_not_matching_preflights = 13;
}

// [#next-free-field: 42]
message RouteAction {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.RouteAction";

  enum ClusterNotFoundResponseCode {
    // HTTP status code - 503 Service Unavailable.
    SERVICE_UNAVAILABLE = 0;

    // HTTP status code - 404 Not Found.
    NOT_FOUND = 1;

    // HTTP status code - 500 Internal Server Error.
    INTERNAL_SERVER_ERROR = 2;
  }

  // Configures :ref:`internal redirect <arch_overview_internal_redirects>` behavior.
  // [#next-major-version: remove this definition - it's defined in the InternalRedirectPolicy message.]
  enum InternalRedirectAction {
    option deprecated = true;

    PASS_THROUGH_INTERNAL_REDIRECT = 0;
    HANDLE_INTERNAL_REDIRECT = 1;
  }

  // The router is capable of shadowing traffic from one cluster to another. The current
  // implementation is "fire and forget," meaning Envoy will not wait for the shadow cluster to
  // respond before returning the response from the primary cluster. All normal statistics are
  // collected for the shadow cluster making this feature useful for testing.
  //
  // During shadowing, the host/authority header is altered such that ``-shadow`` is appended. This is
  // useful for logging. For example, ``cluster1`` becomes ``cluster1-shadow``. This behavior can be
  // disabled by setting ``disable_shadow_host_suffix_append`` to ``true``.
  //
  // .. note::
  //
  //   Shadowing will not be triggered if the primary cluster does not exist.
  //
  // .. note::
  //
  //   Shadowing doesn't support Http CONNECT and upgrades.
  // [#next-free-field: 7]
  message RequestMirrorPolicy {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RouteAction.RequestMirrorPolicy";

    reserved 2;

    reserved "runtime_key";

    // Only one of ``cluster`` and ``cluster_header`` can be specified.
    // [#next-major-version: Need to add back the validation rule: (validate.rules).string = {min_len: 1}]
    // Specifies the cluster that requests will be mirrored to. The cluster must
    // exist in the cluster manager configuration.
    string cluster = 1 [(udpa.annotations.field_migrate).oneof_promotion = "cluster_specifier"];

    // Only one of ``cluster`` and ``cluster_header`` can be specified.
    // Envoy will determine the cluster to route to by reading the value of the
    // HTTP header named by cluster_header from the request headers. Only the first value in header is used,
    // and no shadow request will happen if the value is not found in headers. Envoy will not wait for
    // the shadow cluster to respond before returning the response from the primary cluster.
    //
    // .. attention::
    //
    //   Internally, Envoy always uses the HTTP/2 ``:authority`` header to represent the HTTP/1
    //   ``Host`` header. Thus, if attempting to match on ``Host``, match on ``:authority`` instead.
    //
    // .. note::
    //
    //   If the header appears multiple times only the first value is used.
    string cluster_header = 5 [
      (validate.rules).string = {well_known_regex: HTTP_HEADER_NAME strict: false},
      (udpa.annotations.field_migrate).oneof_promotion = "cluster_specifier"
    ];

    // If not specified, all requests to the target cluster will be mirrored.
    //
    // If specified, this field takes precedence over the ``runtime_key`` field and requests must also
    // fall under the percentage of matches indicated by this field.
    //
    // For some fraction N/D, a random number in the range [0,D) is selected. If the
    // number is <= the value of the numerator N, or if the key is not present, the default
    // value, the request will be mirrored.
    core.v3.RuntimeFractionalPercent runtime_fraction = 3;

    // Specifies whether the trace span for the shadow request should be sampled. If this field is not explicitly set,
    // the shadow request will inherit the sampling decision of its parent span. This ensures consistency with the trace
    // sampling policy of the original request and prevents oversampling, especially in scenarios where runtime sampling
    // is disabled.
    google.protobuf.BoolValue trace_sampled = 4;

    // Disables appending the ``-shadow`` suffix to the shadowed ``Host`` header. Defaults to ``false``.
    bool disable_shadow_host_suffix_append = 6;
  }

  // Specifies the route's hashing policy if the upstream cluster uses a hashing :ref:`load balancer
  // <arch_overview_load_balancing_types>`.
  // [#next-free-field: 7]
  message HashPolicy {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RouteAction.HashPolicy";

    message Header {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RouteAction.HashPolicy.Header";

      // The name of the request header that will be used to obtain the hash
      // key. If the request header is not present, no hash will be produced.
      string header_name = 1
          [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}];

      // If specified, the request header value will be rewritten and used
      // to produce the hash key.
      type.matcher.v3.RegexMatchAndSubstitute regex_rewrite = 2;
    }

    // CookieAttribute defines an API for adding additional attributes for a HTTP cookie.
    message CookieAttribute {
      // The name of the cookie attribute.
      string name = 1
          [(validate.rules).string =
               {min_len: 1 max_bytes: 16384 well_known_regex: HTTP_HEADER_NAME strict: false}];

      // The optional value of the cookie attribute.
      string value = 2 [(validate.rules).string =
                            {max_bytes: 16384 well_known_regex: HTTP_HEADER_VALUE strict: false}];
    }

    // Envoy supports two types of cookie affinity:
    //
    // 1. Passive. Envoy takes a cookie that's present in the cookies header and
    //    hashes on its value.
    //
    // 2. Generated. Envoy generates and sets a cookie with an expiration (TTL)
    //    on the first request from the client in its response to the client,
    //    based on the endpoint the request gets sent to. The client then
    //    presents this on the next and all subsequent requests. The hash of
    //    this is sufficient to ensure these requests get sent to the same
    //    endpoint. The cookie is generated by hashing the source and
    //    destination ports and addresses so that multiple independent HTTP2
    //    streams on the same connection will independently receive the same
    //    cookie, even if they arrive at the Envoy simultaneously.
    message Cookie {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RouteAction.HashPolicy.Cookie";

      // The name of the cookie that will be used to obtain the hash key. If the
      // cookie is not present and ttl below is not set, no hash will be
      // produced.
      string name = 1 [(validate.rules).string = {min_len: 1}];

      // If specified, a cookie with the TTL will be generated if the cookie is
      // not present. If the TTL is present and zero, the generated cookie will
      // be a session cookie.
      google.protobuf.Duration ttl = 2;

      // The name of the path for the cookie. If no path is specified here, no path
      // will be set for the cookie.
      string path = 3;

      // Additional attributes for the cookie. They will be used when generating a new cookie.
      repeated CookieAttribute attributes = 4;
    }

    message ConnectionProperties {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RouteAction.HashPolicy.ConnectionProperties";

      // Hash on source IP address.
      bool source_ip = 1;
    }

    message QueryParameter {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RouteAction.HashPolicy.QueryParameter";

      // The name of the URL query parameter that will be used to obtain the hash
      // key. If the parameter is not present, no hash will be produced. Query
      // parameter names are case-sensitive. If query parameters are repeated, only
      // the first value will be considered.
      string name = 1 [(validate.rules).string = {min_len: 1}];
    }

    message FilterState {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RouteAction.HashPolicy.FilterState";

      // The name of the Object in the per-request filterState, which is an
      // Envoy::Hashable object. If there is no data associated with the key,
      // or the stored object is not Envoy::Hashable, no hash will be produced.
      string key = 1 [(validate.rules).string = {min_len: 1}];
    }

    oneof policy_specifier {
      option (validate.required) = true;

      // Header hash policy.
      Header header = 1;

      // Cookie hash policy.
      Cookie cookie = 2;

      // Connection properties hash policy.
      ConnectionProperties connection_properties = 3;

      // Query parameter hash policy.
      QueryParameter query_parameter = 5;

      // Filter state hash policy.
      FilterState filter_state = 6;
    }

    // The flag that short-circuits the hash computing. This field provides a
    // 'fallback' style of configuration: "if a terminal policy doesn't work,
    // fallback to rest of the policy list", it saves time when the terminal
    // policy works.
    //
    // If true, and there is already a hash computed, ignore rest of the
    // list of hash polices.
    // For example, if the following hash methods are configured:
    //
    //  ========= ========
    //  specifier terminal
    //  ========= ========
    //  Header A  true
    //  Header B  false
    //  Header C  false
    //  ========= ========
    //
    // The generateHash process ends if policy "header A" generates a hash, as
    // it's a terminal policy.
    bool terminal = 4;
  }

  // Allows enabling and disabling upgrades on a per-route basis.
  // This overrides any enabled/disabled upgrade filter chain specified in the
  // HttpConnectionManager
  // :ref:`upgrade_configs
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.upgrade_configs>`
  // but does not affect any custom filter chain specified there.
  message UpgradeConfig {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RouteAction.UpgradeConfig";

    // Configuration for sending data upstream as a raw data payload. This is used for
    // CONNECT or POST requests, when forwarding request payload as raw TCP.
    message ConnectConfig {
      // If present, the proxy protocol header will be prepended to the CONNECT payload sent upstream.
      core.v3.ProxyProtocolConfig proxy_protocol_config = 1;

      // If set, the route will also allow forwarding POST payload as raw TCP.
      bool allow_post = 2;
    }

    // The case-insensitive name of this upgrade, e.g. "websocket".
    // For each upgrade type present in upgrade_configs, requests with
    // Upgrade: [upgrade_type] will be proxied upstream.
    string upgrade_type = 1
        [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_VALUE strict: false}];

    // Determines if upgrades are available on this route. Defaults to true.
    google.protobuf.BoolValue enabled = 2;

    // Configuration for sending data upstream as a raw data payload. This is used for
    // CONNECT requests, when forwarding CONNECT payload as raw TCP.
    // Note that CONNECT support is currently considered alpha in Envoy.
    // [#comment: TODO(htuch): Replace the above comment with an alpha tag.]
    ConnectConfig connect_config = 3;
  }

  message MaxStreamDuration {
    // Specifies the maximum duration allowed for streams on the route. If not specified, the value
    // from the :ref:`max_stream_duration
    // <envoy_v3_api_field_config.core.v3.HttpProtocolOptions.max_stream_duration>` field in
    // :ref:`HttpConnectionManager.common_http_protocol_options
    // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.common_http_protocol_options>`
    // is used. If this field is set explicitly to zero, any
    // HttpConnectionManager max_stream_duration timeout will be disabled for
    // this route.
    google.protobuf.Duration max_stream_duration = 1;

    // If present, and the request contains a `grpc-timeout header
    // <https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md>`_, use that value as the
    // ``max_stream_duration``, but limit the applied timeout to the maximum value specified here.
    // If set to 0, the ``grpc-timeout`` header is used without modification.
    google.protobuf.Duration grpc_timeout_header_max = 2;

    // If present, Envoy will adjust the timeout provided by the ``grpc-timeout`` header by
    // subtracting the provided duration from the header. This is useful for allowing Envoy to set
    // its global timeout to be less than that of the deadline imposed by the calling client, which
    // makes it more likely that Envoy will handle the timeout instead of having the call canceled
    // by the client. If, after applying the offset, the resulting timeout is zero or negative,
    // the stream will timeout immediately.
    google.protobuf.Duration grpc_timeout_header_offset = 3;
  }

  reserved 12, 18, 19, 16, 22, 21, 10;

  reserved "request_mirror_policy";

  oneof cluster_specifier {
    option (validate.required) = true;

    // Indicates the upstream cluster to which the request should be routed
    // to.
    string cluster = 1 [(validate.rules).string = {min_len: 1}];

    // Envoy will determine the cluster to route to by reading the value of the
    // HTTP header named by cluster_header from the request headers. If the
    // header is not found or the referenced cluster does not exist, Envoy will
    // return a 404 response.
    //
    // .. attention::
    //
    //   Internally, Envoy always uses the HTTP/2 ``:authority`` header to represent the HTTP/1
    //   ``Host`` header. Thus, if attempting to match on ``Host``, match on ``:authority`` instead.
    //
    // .. note::
    //
    //   If the header appears multiple times only the first value is used.
    string cluster_header = 2
        [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}];

    // Multiple upstream clusters can be specified for a given route. The
    // request is routed to one of the upstream clusters based on weights
    // assigned to each cluster. See
    // :ref:`traffic splitting <config_http_conn_man_route_table_traffic_splitting_split>`
    // for additional documentation.
    WeightedCluster weighted_clusters = 3;

    // Name of the cluster specifier plugin to use to determine the cluster for requests on this route.
    // The cluster specifier plugin name must be defined in the associated
    // :ref:`cluster specifier plugins <envoy_v3_api_field_config.route.v3.RouteConfiguration.cluster_specifier_plugins>`
    // in the :ref:`name <envoy_v3_api_field_config.core.v3.TypedExtensionConfig.name>` field.
    string cluster_specifier_plugin = 37;

    // Custom cluster specifier plugin configuration to use to determine the cluster for requests
    // on this route.
    ClusterSpecifierPlugin inline_cluster_specifier_plugin = 39;
  }

  // The HTTP status code to use when configured cluster is not found.
  // The default response code is 503 Service Unavailable.
  ClusterNotFoundResponseCode cluster_not_found_response_code = 20
      [(validate.rules).enum = {defined_only: true}];

  // Optional endpoint metadata match criteria used by the subset load balancer. Only endpoints
  // in the upstream cluster with metadata matching what's set in this field will be considered
  // for load balancing. If using :ref:`weighted_clusters
  // <envoy_v3_api_field_config.route.v3.RouteAction.weighted_clusters>`, metadata will be merged, with values
  // provided there taking precedence. The filter name should be specified as ``envoy.lb``.
  core.v3.Metadata metadata_match = 4;

  // Indicates that during forwarding, the matched prefix (or path) should be
  // swapped with this value. This option allows application URLs to be rooted
  // at a different path from those exposed at the reverse proxy layer. The router filter will
  // place the original path before rewrite into the :ref:`x-envoy-original-path
  // <config_http_filters_router_x-envoy-original-path>` header.
  //
  // Only one of :ref:`regex_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.regex_rewrite>`
  // :ref:`path_rewrite_policy <envoy_v3_api_field_config.route.v3.RouteAction.path_rewrite_policy>`,
  // or :ref:`prefix_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.prefix_rewrite>` may be specified.
  //
  // .. attention::
  //
  //   Pay careful attention to the use of trailing slashes in the
  //   :ref:`route's match <envoy_v3_api_field_config.route.v3.Route.match>` prefix value.
  //   Stripping a prefix from a path requires multiple Routes to handle all cases. For example,
  //   rewriting ``/prefix`` to ``/`` and ``/prefix/etc`` to ``/etc`` cannot be done in a single
  //   :ref:`Route <envoy_v3_api_msg_config.route.v3.Route>`, as shown by the below config entries:
  //
  //   .. code-block:: yaml
  //
  //     - match:
  //         prefix: "/prefix/"
  //       route:
  //         prefix_rewrite: "/"
  //     - match:
  //         prefix: "/prefix"
  //       route:
  //         prefix_rewrite: "/"
  //
  //   Having above entries in the config, requests to ``/prefix`` will be stripped to ``/``, while
  //   requests to ``/prefix/etc`` will be stripped to ``/etc``.
  string prefix_rewrite = 5
      [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];

  // Indicates that during forwarding, portions of the path that match the
  // pattern should be rewritten, even allowing the substitution of capture
  // groups from the pattern into the new path as specified by the rewrite
  // substitution string. This is useful to allow application paths to be
  // rewritten in a way that is aware of segments with variable content like
  // identifiers. The router filter will place the original path as it was
  // before the rewrite into the :ref:`x-envoy-original-path
  // <config_http_filters_router_x-envoy-original-path>` header.
  //
  // Only one of :ref:`regex_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.regex_rewrite>`,
  // :ref:`prefix_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.prefix_rewrite>`, or
  // :ref:`path_rewrite_policy <envoy_v3_api_field_config.route.v3.RouteAction.path_rewrite_policy>`]
  // may be specified.
  //
  // Examples using Google's `RE2 <https://github.com/google/re2>`_ engine:
  //
  // * The path pattern ``^/service/([^/]+)(/.*)$`` paired with a substitution
  //   string of ``\2/instance/\1`` would transform ``/service/foo/v1/api``
  //   into ``/v1/api/instance/foo``.
  //
  // * The pattern ``one`` paired with a substitution string of ``two`` would
  //   transform ``/xxx/one/yyy/one/zzz`` into ``/xxx/two/yyy/two/zzz``.
  //
  // * The pattern ``^(.*?)one(.*)$`` paired with a substitution string of
  //   ``\1two\2`` would replace only the first occurrence of ``one``,
  //   transforming path ``/xxx/one/yyy/one/zzz`` into ``/xxx/two/yyy/one/zzz``.
  //
  // * The pattern ``(?i)/xxx/`` paired with a substitution string of ``/yyy/``
  //   would do a case-insensitive match and transform path ``/aaa/XxX/bbb`` to
  //   ``/aaa/yyy/bbb``.
  type.matcher.v3.RegexMatchAndSubstitute regex_rewrite = 32;

  // [#extension-category: envoy.path.rewrite]
  core.v3.TypedExtensionConfig path_rewrite_policy = 41;

  // If one of the host rewrite specifiers is set and the
  // :ref:`suppress_envoy_headers
  // <envoy_v3_api_field_extensions.filters.http.router.v3.Router.suppress_envoy_headers>` flag is not
  // set to true, the router filter will place the original host header value before
  // rewriting into the :ref:`x-envoy-original-host
  // <config_http_filters_router_x-envoy-original-host>` header.
  //
  // And if the
  // :ref:`append_x_forwarded_host <envoy_v3_api_field_config.route.v3.RouteAction.append_x_forwarded_host>`
  // is set to true, the original host value will also be appended to the
  // :ref:`config_http_conn_man_headers_x-forwarded-host` header.
  //
  oneof host_rewrite_specifier {
    // Indicates that during forwarding, the host header will be swapped with
    // this value.
    string host_rewrite_literal = 6
        [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];

    // Indicates that during forwarding, the host header will be swapped with
    // the hostname of the upstream host chosen by the cluster manager. This
    // option is applicable only when the destination cluster for a route is of
    // type ``strict_dns`` or ``logical_dns``,
    // or when :ref:`hostname <envoy_v3_api_field_config.endpoint.v3.Endpoint.hostname>`
    // field is not empty. Setting this to true with other cluster types
    // has no effect.
    google.protobuf.BoolValue auto_host_rewrite = 7;

    // Indicates that during forwarding, the host header will be swapped with the content of given
    // downstream or :ref:`custom <config_http_conn_man_headers_custom_request_headers>` header.
    // If header value is empty, host header is left intact.
    //
    // .. attention::
    //
    //   Pay attention to the potential security implications of using this option. Provided header
    //   must come from trusted source.
    //
    // .. note::
    //
    //   If the header appears multiple times only the first value is used.
    string host_rewrite_header = 29
        [(validate.rules).string = {well_known_regex: HTTP_HEADER_NAME strict: false}];

    // Indicates that during forwarding, the host header will be swapped with
    // the result of the regex substitution executed on path value with query and fragment removed.
    // This is useful for transitioning variable content between path segment and subdomain.
    //
    // For example with the following config:
    //
    //   .. code-block:: yaml
    //
    //     host_rewrite_path_regex:
    //       pattern:
    //         google_re2: {}
    //         regex: "^/(.+)/.+$"
    //       substitution: \1
    //
    // Would rewrite the host header to ``envoyproxy.io`` given the path ``/envoyproxy.io/some/path``.
    type.matcher.v3.RegexMatchAndSubstitute host_rewrite_path_regex = 35;
  }

  // If set, then a host rewrite action (one of
  // :ref:`host_rewrite_literal <envoy_v3_api_field_config.route.v3.RouteAction.host_rewrite_literal>`,
  // :ref:`auto_host_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.auto_host_rewrite>`,
  // :ref:`host_rewrite_header <envoy_v3_api_field_config.route.v3.RouteAction.host_rewrite_header>`, or
  // :ref:`host_rewrite_path_regex <envoy_v3_api_field_config.route.v3.RouteAction.host_rewrite_path_regex>`)
  // causes the original value of the host header, if any, to be appended to the
  // :ref:`config_http_conn_man_headers_x-forwarded-host` HTTP header if it is different to the last value appended.
  bool append_x_forwarded_host = 38;

  // Specifies the upstream timeout for the route. If not specified, the default is 15s. This
  // spans between the point at which the entire downstream request (i.e. end-of-stream) has been
  // processed and when the upstream response has been completely processed. A value of 0 will
  // disable the route's timeout.
  //
  // .. note::
  //
  //   This timeout includes all retries. See also
  //   :ref:`config_http_filters_router_x-envoy-upstream-rq-timeout-ms`,
  //   :ref:`config_http_filters_router_x-envoy-upstream-rq-per-try-timeout-ms`, and the
  //   :ref:`retry overview <arch_overview_http_routing_retry>`.
  google.protobuf.Duration timeout = 8;

  // Specifies the idle timeout for the route. If not specified, there is no per-route idle timeout,
  // although the connection manager wide :ref:`stream_idle_timeout
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.stream_idle_timeout>`
  // will still apply. A value of 0 will completely disable the route's idle timeout, even if a
  // connection manager stream idle timeout is configured.
  //
  // The idle timeout is distinct to :ref:`timeout
  // <envoy_v3_api_field_config.route.v3.RouteAction.timeout>`, which provides an upper bound
  // on the upstream response time; :ref:`idle_timeout
  // <envoy_v3_api_field_config.route.v3.RouteAction.idle_timeout>` instead bounds the amount
  // of time the request's stream may be idle.
  //
  // After header decoding, the idle timeout will apply on downstream and
  // upstream request events. Each time an encode/decode event for headers or
  // data is processed for the stream, the timer will be reset. If the timeout
  // fires, the stream is terminated with a 408 Request Timeout error code if no
  // upstream response header has been received, otherwise a stream reset
  // occurs.
  //
  // If the :ref:`overload action <config_overload_manager_overload_actions>` "envoy.overload_actions.reduce_timeouts"
  // is configured, this timeout is scaled according to the value for
  // :ref:`HTTP_DOWNSTREAM_STREAM_IDLE <envoy_v3_api_enum_value_config.overload.v3.ScaleTimersOverloadActionConfig.TimerType.HTTP_DOWNSTREAM_STREAM_IDLE>`.
  google.protobuf.Duration idle_timeout = 24;

  // Specifies how to send request over TLS early data.
  // If absent, allows `safe HTTP requests <https://www.rfc-editor.org/rfc/rfc7231#section-4.2.1>`_ to be sent on early data.
  // [#extension-category: envoy.route.early_data_policy]
  core.v3.TypedExtensionConfig early_data_policy = 40;

  // Indicates that the route has a retry policy. Note that if this is set,
  // it'll take precedence over the virtual host level retry policy entirely
  // (e.g.: policies are not merged, most internal one becomes the enforced policy).
  RetryPolicy retry_policy = 9;

  // [#not-implemented-hide:]
  // Specifies the configuration for retry policy extension. Note that if this is set, it'll take
  // precedence over the virtual host level retry policy entirely (e.g.: policies are not merged,
  // most internal one becomes the enforced policy). :ref:`Retry policy <envoy_v3_api_field_config.route.v3.VirtualHost.retry_policy>`
  // should not be set if this field is used.
  google.protobuf.Any retry_policy_typed_config = 33;

  // Specify a set of route request mirroring policies.
  // It takes precedence over the virtual host and route config mirror policy entirely.
  // That is, policies are not merged, the most specific non-empty one becomes the mirror policies.
  repeated RequestMirrorPolicy request_mirror_policies = 30;

  // Optionally specifies the :ref:`routing priority <arch_overview_http_routing_priority>`.
  core.v3.RoutingPriority priority = 11 [(validate.rules).enum = {defined_only: true}];

  // Specifies a set of rate limit configurations that could be applied to the
  // route.
  repeated RateLimit rate_limits = 13;

  // Specifies if the rate limit filter should include the virtual host rate
  // limits. By default, if the route configured rate limits, the virtual host
  // :ref:`rate_limits <envoy_v3_api_field_config.route.v3.VirtualHost.rate_limits>` are not applied to the
  // request.
  //
  // This field is deprecated. Please use :ref:`vh_rate_limits <envoy_v3_api_field_extensions.filters.http.ratelimit.v3.RateLimitPerRoute.vh_rate_limits>`
  google.protobuf.BoolValue include_vh_rate_limits = 14
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // Specifies a list of hash policies to use for ring hash load balancing. Each
  // hash policy is evaluated individually and the combined result is used to
  // route the request. The method of combination is deterministic such that
  // identical lists of hash policies will produce the same hash. Since a hash
  // policy examines specific parts of a request, it can fail to produce a hash
  // (i.e. if the hashed header is not present). If (and only if) all configured
  // hash policies fail to generate a hash, no hash will be produced for
  // the route. In this case, the behavior is the same as if no hash policies
  // were specified (i.e. the ring hash load balancer will choose a random
  // backend). If a hash policy has the "terminal" attribute set to true, and
  // there is already a hash generated, the hash is returned immediately,
  // ignoring the rest of the hash policy list.
  repeated HashPolicy hash_policy = 15;

  // Indicates that the route has a CORS policy. This field is ignored if related cors policy is
  // found in the :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>` or
  // :ref:`WeightedCluster.ClusterWeight.typed_per_filter_config<envoy_v3_api_field_config.route.v3.WeightedCluster.ClusterWeight.typed_per_filter_config>`.
  //
  // .. attention::
  //
  //   This option has been deprecated. Please use
  //   :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>` or
  //   :ref:`WeightedCluster.ClusterWeight.typed_per_filter_config<envoy_v3_api_field_config.route.v3.WeightedCluster.ClusterWeight.typed_per_filter_config>`
  //   to configure the CORS HTTP filter.
  CorsPolicy cors = 17 [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // Deprecated by :ref:`grpc_timeout_header_max <envoy_v3_api_field_config.route.v3.RouteAction.MaxStreamDuration.grpc_timeout_header_max>`
  // If present, and the request is a gRPC request, use the
  // `grpc-timeout header <https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md>`_,
  // or its default value (infinity) instead of
  // :ref:`timeout <envoy_v3_api_field_config.route.v3.RouteAction.timeout>`, but limit the applied timeout
  // to the maximum value specified here. If configured as 0, the maximum allowed timeout for
  // gRPC requests is infinity. If not configured at all, the ``grpc-timeout`` header is not used
  // and gRPC requests time out like any other requests using
  // :ref:`timeout <envoy_v3_api_field_config.route.v3.RouteAction.timeout>` or its default.
  // This can be used to prevent unexpected upstream request timeouts due to potentially long
  // time gaps between gRPC request and response in gRPC streaming mode.
  //
  // .. note::
  //
  //    If a timeout is specified using :ref:`config_http_filters_router_x-envoy-upstream-rq-timeout-ms`, it takes
  //    precedence over `grpc-timeout header <https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md>`_, when
  //    both are present. See also
  //    :ref:`config_http_filters_router_x-envoy-upstream-rq-timeout-ms`,
  //    :ref:`config_http_filters_router_x-envoy-upstream-rq-per-try-timeout-ms`, and the
  //    :ref:`retry overview <arch_overview_http_routing_retry>`.
  google.protobuf.Duration max_grpc_timeout = 23
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // Deprecated by :ref:`grpc_timeout_header_offset <envoy_v3_api_field_config.route.v3.RouteAction.MaxStreamDuration.grpc_timeout_header_offset>`.
  // If present, Envoy will adjust the timeout provided by the ``grpc-timeout`` header by subtracting
  // the provided duration from the header. This is useful in allowing Envoy to set its global
  // timeout to be less than that of the deadline imposed by the calling client, which makes it more
  // likely that Envoy will handle the timeout instead of having the call canceled by the client.
  // The offset will only be applied if the provided grpc_timeout is greater than the offset. This
  // ensures that the offset will only ever decrease the timeout and never set it to 0 (meaning
  // infinity).
  google.protobuf.Duration grpc_timeout_offset = 28
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  repeated UpgradeConfig upgrade_configs = 25;

  // If present, Envoy will try to follow an upstream redirect response instead of proxying the
  // response back to the downstream. An upstream redirect response is defined
  // by :ref:`redirect_response_codes
  // <envoy_v3_api_field_config.route.v3.InternalRedirectPolicy.redirect_response_codes>`.
  InternalRedirectPolicy internal_redirect_policy = 34;

  InternalRedirectAction internal_redirect_action = 26
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // An internal redirect is handled, iff the number of previous internal redirects that a
  // downstream request has encountered is lower than this value, and
  // :ref:`internal_redirect_action <envoy_v3_api_field_config.route.v3.RouteAction.internal_redirect_action>`
  // is set to :ref:`HANDLE_INTERNAL_REDIRECT
  // <envoy_v3_api_enum_value_config.route.v3.RouteAction.InternalRedirectAction.HANDLE_INTERNAL_REDIRECT>`
  // In the case where a downstream request is bounced among multiple routes by internal redirect,
  // the first route that hits this threshold, or has
  // :ref:`internal_redirect_action <envoy_v3_api_field_config.route.v3.RouteAction.internal_redirect_action>`
  // set to
  // :ref:`PASS_THROUGH_INTERNAL_REDIRECT
  // <envoy_v3_api_enum_value_config.route.v3.RouteAction.InternalRedirectAction.PASS_THROUGH_INTERNAL_REDIRECT>`
  // will pass the redirect back to downstream.
  //
  // If not specified, at most one redirect will be followed.
  google.protobuf.UInt32Value max_internal_redirects = 31
      [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

  // Indicates that the route has a hedge policy. Note that if this is set,
  // it'll take precedence over the virtual host level hedge policy entirely
  // (e.g.: policies are not merged, most internal one becomes the enforced policy).
  HedgePolicy hedge_policy = 27;

  // Specifies the maximum stream duration for this route.
  MaxStreamDuration max_stream_duration = 36;
}

// HTTP retry :ref:`architecture overview <arch_overview_http_routing_retry>`.
// [#next-free-field: 14]
message RetryPolicy {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.RetryPolicy";

  enum ResetHeaderFormat {
    SECONDS = 0;
    UNIX_TIMESTAMP = 1;
  }

  message RetryPriority {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RetryPolicy.RetryPriority";

    reserved 2;

    reserved "config";

    string name = 1 [(validate.rules).string = {min_len: 1}];

    // [#extension-category: envoy.retry_priorities]
    oneof config_type {
      google.protobuf.Any typed_config = 3;
    }
  }

  message RetryHostPredicate {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RetryPolicy.RetryHostPredicate";

    reserved 2;

    reserved "config";

    string name = 1 [(validate.rules).string = {min_len: 1}];

    // [#extension-category: envoy.retry_host_predicates]
    oneof config_type {
      google.protobuf.Any typed_config = 3;
    }
  }

  message RetryBackOff {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RetryPolicy.RetryBackOff";

    // Specifies the base interval between retries. This parameter is required and must be greater
    // than zero. Values less than 1 ms are rounded up to 1 ms.
    // See :ref:`config_http_filters_router_x-envoy-max-retries` for a discussion of Envoy's
    // back-off algorithm.
    google.protobuf.Duration base_interval = 1 [(validate.rules).duration = {
      required: true
      gt {}
    }];

    // Specifies the maximum interval between retries. This parameter is optional, but must be
    // greater than or equal to the ``base_interval`` if set. The default is 10 times the
    // ``base_interval``. See :ref:`config_http_filters_router_x-envoy-max-retries` for a discussion
    // of Envoy's back-off algorithm.
    google.protobuf.Duration max_interval = 2 [(validate.rules).duration = {gt {}}];
  }

  message ResetHeader {
    // The name of the reset header.
    //
    // .. note::
    //
    //   If the header appears multiple times only the first value is used.
    string name = 1
        [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}];

    // The format of the reset header.
    ResetHeaderFormat format = 2 [(validate.rules).enum = {defined_only: true}];
  }

  // A retry back-off strategy that applies when the upstream server rate limits
  // the request.
  //
  // Given this configuration:
  //
  // .. code-block:: yaml
  //
  //   rate_limited_retry_back_off:
  //     reset_headers:
  //     - name: Retry-After
  //       format: SECONDS
  //     - name: X-RateLimit-Reset
  //       format: UNIX_TIMESTAMP
  //     max_interval: "300s"
  //
  // The following algorithm will apply:
  //
  //  1. If the response contains the header ``Retry-After`` its value must be on
  //     the form ``120`` (an integer that represents the number of seconds to
  //     wait before retrying). If so, this value is used as the back-off interval.
  //  2. Otherwise, if the response contains the header ``X-RateLimit-Reset`` its
  //     value must be on the form ``1595320702`` (an integer that represents the
  //     point in time at which to retry, as a Unix timestamp in seconds). If so,
  //     the current time is subtracted from this value and the result is used as
  //     the back-off interval.
  //  3. Otherwise, Envoy will use the default
  //     :ref:`exponential back-off <envoy_v3_api_field_config.route.v3.RetryPolicy.retry_back_off>`
  //     strategy.
  //
  // No matter which format is used, if the resulting back-off interval exceeds
  // ``max_interval`` it is discarded and the next header in ``reset_headers``
  // is tried. If a request timeout is configured for the route it will further
  // limit how long the request will be allowed to run.
  //
  // To prevent many clients retrying at the same point in time jitter is added
  // to the back-off interval, so the resulting interval is decided by taking:
  // ``random(interval, interval * 1.5)``.
  //
  // .. attention::
  //
  //   Configuring ``rate_limited_retry_back_off`` will not by itself cause a request
  //   to be retried. You will still need to configure the right retry policy to match
  //   the responses from the upstream server.
  message RateLimitedRetryBackOff {
    // Specifies the reset headers (like ``Retry-After`` or ``X-RateLimit-Reset``)
    // to match against the response. Headers are tried in order, and matched case
    // insensitive. The first header to be parsed successfully is used. If no headers
    // match the default exponential back-off is used instead.
    repeated ResetHeader reset_headers = 1 [(validate.rules).repeated = {min_items: 1}];

    // Specifies the maximum back off interval that Envoy will allow. If a reset
    // header contains an interval longer than this then it will be discarded and
    // the next header will be tried. Defaults to 300 seconds.
    google.protobuf.Duration max_interval = 2 [(validate.rules).duration = {gt {}}];
  }

  // Specifies the conditions under which retry takes place. These are the same
  // conditions documented for :ref:`config_http_filters_router_x-envoy-retry-on` and
  // :ref:`config_http_filters_router_x-envoy-retry-grpc-on`.
  string retry_on = 1;

  // Specifies the allowed number of retries. This parameter is optional and
  // defaults to 1. These are the same conditions documented for
  // :ref:`config_http_filters_router_x-envoy-max-retries`.
  google.protobuf.UInt32Value num_retries = 2
      [(udpa.annotations.field_migrate).rename = "max_retries"];

  // Specifies a non-zero upstream timeout per retry attempt (including the initial attempt). This
  // parameter is optional. The same conditions documented for
  // :ref:`config_http_filters_router_x-envoy-upstream-rq-per-try-timeout-ms` apply.
  //
  // .. note::
  //
  //   If left unspecified, Envoy will use the global
  //   :ref:`route timeout <envoy_v3_api_field_config.route.v3.RouteAction.timeout>` for the request.
  //   Consequently, when using a :ref:`5xx <config_http_filters_router_x-envoy-retry-on>` based
  //   retry policy, a request that times out will not be retried as the total timeout budget
  //   would have been exhausted.
  google.protobuf.Duration per_try_timeout = 3;

  // Specifies an upstream idle timeout per retry attempt (including the initial attempt). This
  // parameter is optional and if absent there is no per try idle timeout. The semantics of the per
  // try idle timeout are similar to the
  // :ref:`route idle timeout <envoy_v3_api_field_config.route.v3.RouteAction.timeout>` and
  // :ref:`stream idle timeout
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.stream_idle_timeout>`
  // both enforced by the HTTP connection manager. The difference is that this idle timeout
  // is enforced by the router for each individual attempt and thus after all previous filters have
  // run, as opposed to *before* all previous filters run for the other idle timeouts. This timeout
  // is useful in cases in which total request timeout is bounded by a number of retries and a
  // :ref:`per_try_timeout <envoy_v3_api_field_config.route.v3.RetryPolicy.per_try_timeout>`, but
  // there is a desire to ensure each try is making incremental progress. Note also that similar
  // to :ref:`per_try_timeout <envoy_v3_api_field_config.route.v3.RetryPolicy.per_try_timeout>`,
  // this idle timeout does not start until after both the entire request has been received by the
  // router *and* a connection pool connection has been obtained. Unlike
  // :ref:`per_try_timeout <envoy_v3_api_field_config.route.v3.RetryPolicy.per_try_timeout>`,
  // the idle timer continues once the response starts streaming back to the downstream client.
  // This ensures that response data continues to make progress without using one of the HTTP
  // connection manager idle timeouts.
  google.protobuf.Duration per_try_idle_timeout = 13;

  // Specifies an implementation of a RetryPriority which is used to determine the
  // distribution of load across priorities used for retries. Refer to
  // :ref:`retry plugin configuration <arch_overview_http_retry_plugins>` for more details.
  RetryPriority retry_priority = 4;

  // Specifies a collection of RetryHostPredicates that will be consulted when selecting a host
  // for retries. If any of the predicates reject the host, host selection will be reattempted.
  // Refer to :ref:`retry plugin configuration <arch_overview_http_retry_plugins>` for more
  // details.
  repeated RetryHostPredicate retry_host_predicate = 5;

  // Retry options predicates that will be applied prior to retrying a request. These predicates
  // allow customizing request behavior between retries.
  // [#comment: add [#extension-category: envoy.retry_options_predicates] when there are built-in extensions]
  repeated core.v3.TypedExtensionConfig retry_options_predicates = 12;

  // The maximum number of times host selection will be reattempted before giving up, at which
  // point the host that was last selected will be routed to. If unspecified, this will default to
  // retrying once.
  int64 host_selection_retry_max_attempts = 6;

  // HTTP status codes that should trigger a retry in addition to those specified by retry_on.
  repeated uint32 retriable_status_codes = 7;

  // Specifies parameters that control exponential retry back off. This parameter is optional, in which case the
  // default base interval is 25 milliseconds or, if set, the current value of the
  // ``upstream.base_retry_backoff_ms`` runtime parameter. The default maximum interval is 10 times
  // the base interval. The documentation for :ref:`config_http_filters_router_x-envoy-max-retries`
  // describes Envoy's back-off algorithm.
  RetryBackOff retry_back_off = 8;

  // Specifies parameters that control a retry back-off strategy that is used
  // when the request is rate limited by the upstream server. The server may
  // return a response header like ``Retry-After`` or ``X-RateLimit-Reset`` to
  // provide feedback to the client on how long to wait before retrying. If
  // configured, this back-off strategy will be used instead of the
  // default exponential back off strategy (configured using ``retry_back_off``)
  // whenever a response includes the matching headers.
  RateLimitedRetryBackOff rate_limited_retry_back_off = 11;

  // HTTP response headers that trigger a retry if present in the response. A retry will be
  // triggered if any of the header matches match the upstream response headers.
  // The field is only consulted if 'retriable-headers' retry policy is active.
  repeated HeaderMatcher retriable_headers = 9;

  // HTTP headers which must be present in the request for retries to be attempted.
  repeated HeaderMatcher retriable_request_headers = 10;
}

// HTTP request hedging :ref:`architecture overview <arch_overview_http_routing_hedging>`.
message HedgePolicy {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.HedgePolicy";

  // Specifies the number of initial requests that should be sent upstream.
  // Must be at least 1.
  // Defaults to 1.
  // [#not-implemented-hide:]
  google.protobuf.UInt32Value initial_requests = 1 [(validate.rules).uint32 = {gte: 1}];

  // Specifies a probability that an additional upstream request should be sent
  // on top of what is specified by initial_requests.
  // Defaults to 0.
  // [#not-implemented-hide:]
  type.v3.FractionalPercent additional_request_chance = 2;

  // Indicates that a hedged request should be sent when the per-try timeout is hit.
  // This means that a retry will be issued without resetting the original request, leaving multiple upstream requests in flight.
  // The first request to complete successfully will be the one returned to the caller.
  //
  // * At any time, a successful response (i.e. not triggering any of the retry-on conditions) would be returned to the client.
  // * Before per-try timeout, an error response (per retry-on conditions) would be retried immediately or returned ot the client
  //   if there are no more retries left.
  // * After per-try timeout, an error response would be discarded, as a retry in the form of a hedged request is already in progress.
  //
  // Note: For this to have effect, you must have a :ref:`RetryPolicy <envoy_v3_api_msg_config.route.v3.RetryPolicy>` that retries at least
  // one error code and specifies a maximum number of retries.
  //
  // Defaults to false.
  bool hedge_on_per_try_timeout = 3;
}

// [#next-free-field: 10]
message RedirectAction {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.RedirectAction";

  enum RedirectResponseCode {
    // Moved Permanently HTTP Status Code - 301.
    MOVED_PERMANENTLY = 0;

    // Found HTTP Status Code - 302.
    FOUND = 1;

    // See Other HTTP Status Code - 303.
    SEE_OTHER = 2;

    // Temporary Redirect HTTP Status Code - 307.
    TEMPORARY_REDIRECT = 3;

    // Permanent Redirect HTTP Status Code - 308.
    PERMANENT_REDIRECT = 4;
  }

  // When the scheme redirection take place, the following rules apply:
  //  1. If the source URI scheme is ``http`` and the port is explicitly
  //     set to ``:80``, the port will be removed after the redirection
  //  2. If the source URI scheme is ``https`` and the port is explicitly
  //     set to ``:443``, the port will be removed after the redirection
  oneof scheme_rewrite_specifier {
    // The scheme portion of the URL will be swapped with "https".
    bool https_redirect = 4;

    // The scheme portion of the URL will be swapped with this value.
    string scheme_redirect = 7;
  }

  // The host portion of the URL will be swapped with this value.
  string host_redirect = 1
      [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];

  // The port value of the URL will be swapped with this value.
  uint32 port_redirect = 8;

  oneof path_rewrite_specifier {
    // The path portion of the URL will be swapped with this value.
    // Please note that query string in path_redirect will override the
    // request's query string and will not be stripped.
    //
    // For example, let's say we have the following routes:
    //
    // - match: { path: "/old-path-1" }
    //   redirect: { path_redirect: "/new-path-1" }
    // - match: { path: "/old-path-2" }
    //   redirect: { path_redirect: "/new-path-2", strip-query: "true" }
    // - match: { path: "/old-path-3" }
    //   redirect: { path_redirect: "/new-path-3?foo=1", strip_query: "true" }
    //
    // 1. if request uri is "/old-path-1?bar=1", users will be redirected to "/new-path-1?bar=1"
    // 2. if request uri is "/old-path-2?bar=1", users will be redirected to "/new-path-2"
    // 3. if request uri is "/old-path-3?bar=1", users will be redirected to "/new-path-3?foo=1"
    string path_redirect = 2
        [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];

    // Indicates that during redirection, the matched prefix (or path)
    // should be swapped with this value. This option allows redirect URLs be dynamically created
    // based on the request.
    //
    // .. attention::
    //
    //   Pay attention to the use of trailing slashes as mentioned in
    //   :ref:`RouteAction's prefix_rewrite <envoy_v3_api_field_config.route.v3.RouteAction.prefix_rewrite>`.
    string prefix_rewrite = 5
        [(validate.rules).string = {well_known_regex: HTTP_HEADER_VALUE strict: false}];

    // Indicates that during redirect, portions of the path that match the
    // pattern should be rewritten, even allowing the substitution of capture
    // groups from the pattern into the new path as specified by the rewrite
    // substitution string. This is useful to allow application paths to be
    // rewritten in a way that is aware of segments with variable content like
    // identifiers.
    //
    // Examples using Google's `RE2 <https://github.com/google/re2>`_ engine:
    //
    // * The path pattern ``^/service/([^/]+)(/.*)$`` paired with a substitution
    //   string of ``\2/instance/\1`` would transform ``/service/foo/v1/api``
    //   into ``/v1/api/instance/foo``.
    //
    // * The pattern ``one`` paired with a substitution string of ``two`` would
    //   transform ``/xxx/one/yyy/one/zzz`` into ``/xxx/two/yyy/two/zzz``.
    //
    // * The pattern ``^(.*?)one(.*)$`` paired with a substitution string of
    //   ``\1two\2`` would replace only the first occurrence of ``one``,
    //   transforming path ``/xxx/one/yyy/one/zzz`` into ``/xxx/two/yyy/one/zzz``.
    //
    // * The pattern ``(?i)/xxx/`` paired with a substitution string of ``/yyy/``
    //   would do a case-insensitive match and transform path ``/aaa/XxX/bbb`` to
    //   ``/aaa/yyy/bbb``.
    type.matcher.v3.RegexMatchAndSubstitute regex_rewrite = 9;
  }

  // The HTTP status code to use in the redirect response. The default response
  // code is MOVED_PERMANENTLY (301).
  RedirectResponseCode response_code = 3 [(validate.rules).enum = {defined_only: true}];

  // Indicates that during redirection, the query portion of the URL will
  // be removed. Default value is false.
  bool strip_query = 6;
}

message DirectResponseAction {
  option (udpa.annotations.versioning).previous_message_type =
      "envoy.api.v2.route.DirectResponseAction";

  // Specifies the HTTP response status to be returned.
  uint32 status = 1 [(validate.rules).uint32 = {lt: 600 gte: 200}];

  // Specifies the content of the response body. If this setting is omitted,
  // no body is included in the generated response.
  //
  // .. note::
  //
  //   Headers can be specified using ``response_headers_to_add`` in the enclosing
  //   :ref:`envoy_v3_api_msg_config.route.v3.Route`, :ref:`envoy_v3_api_msg_config.route.v3.RouteConfiguration` or
  //   :ref:`envoy_v3_api_msg_config.route.v3.VirtualHost`.
  core.v3.DataSource body = 2;
}

// [#not-implemented-hide:]
message NonForwardingAction {
}

message Decorator {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.Decorator";

  // The operation name associated with the request matched to this route. If tracing is
  // enabled, this information will be used as the span name reported for this request.
  //
  // .. note::
  //
  //   For ingress (inbound) requests, or egress (outbound) responses, this value may be overridden
  //   by the :ref:`x-envoy-decorator-operation
  //   <config_http_filters_router_x-envoy-decorator-operation>` header.
  string operation = 1 [(validate.rules).string = {min_len: 1}];

  // Whether the decorated details should be propagated to the other party. The default is true.
  google.protobuf.BoolValue propagate = 2;
}

message Tracing {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.Tracing";

  // Target percentage of requests managed by this HTTP connection manager that will be force
  // traced if the :ref:`x-client-trace-id <config_http_conn_man_headers_x-client-trace-id>`
  // header is set. This field is a direct analog for the runtime variable
  // 'tracing.client_enabled' in the :ref:`HTTP Connection Manager
  // <config_http_conn_man_runtime>`.
  // Default: 100%
  type.v3.FractionalPercent client_sampling = 1;

  // Target percentage of requests managed by this HTTP connection manager that will be randomly
  // selected for trace generation, if not requested by the client or not forced. This field is
  // a direct analog for the runtime variable 'tracing.random_sampling' in the
  // :ref:`HTTP Connection Manager <config_http_conn_man_runtime>`.
  // Default: 100%
  type.v3.FractionalPercent random_sampling = 2;

  // Target percentage of requests managed by this HTTP connection manager that will be traced
  // after all other sampling checks have been applied (client-directed, force tracing, random
  // sampling). This field functions as an upper limit on the total configured sampling rate. For
  // instance, setting client_sampling to 100% but overall_sampling to 1% will result in only 1%
  // of client requests with the appropriate headers to be force traced. This field is a direct
  // analog for the runtime variable 'tracing.global_enabled' in the
  // :ref:`HTTP Connection Manager <config_http_conn_man_runtime>`.
  // Default: 100%
  type.v3.FractionalPercent overall_sampling = 3;

  // A list of custom tags with unique tag name to create tags for the active span.
  // It will take effect after merging with the :ref:`corresponding configuration
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.Tracing.custom_tags>`
  // configured in the HTTP connection manager. If two tags with the same name are configured
  // each in the HTTP connection manager and the route level, the one configured here takes
  // priority.
  repeated type.tracing.v3.CustomTag custom_tags = 4;
}

// A virtual cluster is a way of specifying a regex matching rule against
// certain important endpoints such that statistics are generated explicitly for
// the matched requests. The reason this is useful is that when doing
// prefix/path matching Envoy does not always know what the application
// considers to be an endpoint. Thus, it’s impossible for Envoy to generically
// emit per endpoint statistics. However, often systems have highly critical
// endpoints that they wish to get “perfect” statistics on. Virtual cluster
// statistics are perfect in the sense that they are emitted on the downstream
// side such that they include network level failures.
//
// Documentation for :ref:`virtual cluster statistics <config_http_filters_router_vcluster_stats>`.
//
// .. note::
//
//    Virtual clusters are a useful tool, but we do not recommend setting up a virtual cluster for
//    every application endpoint. This is both not easily maintainable and as well the matching and
//    statistics output are not free.
message VirtualCluster {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.VirtualCluster";

  reserved 1, 3;

  reserved "pattern", "method";

  // Specifies a list of header matchers to use for matching requests. Each specified header must
  // match. The pseudo-headers ``:path`` and ``:method`` can be used to match the request path and
  // method, respectively.
  repeated HeaderMatcher headers = 4;

  // Specifies the name of the virtual cluster. The virtual cluster name as well
  // as the virtual host name are used when emitting statistics. The statistics are emitted by the
  // router filter and are documented :ref:`here <config_http_filters_router_stats>`.
  string name = 2 [(validate.rules).string = {min_len: 1}];
}

// Global rate limiting :ref:`architecture overview <arch_overview_global_rate_limit>`.
// Also applies to Local rate limiting :ref:`using descriptors <config_http_filters_local_rate_limit_descriptors>`.
// [#next-free-field: 7]
message RateLimit {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.RateLimit";

  // [#next-free-field: 13]
  message Action {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.api.v2.route.RateLimit.Action";

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("source_cluster", "<local service cluster>")
    //
    // <local service cluster> is derived from the :option:`--service-cluster` option.
    message SourceCluster {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.SourceCluster";
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("destination_cluster", "<routed target cluster>")
    //
    // Once a request matches against a route table rule, a routed cluster is determined by one of
    // the following :ref:`route table configuration <envoy_v3_api_msg_config.route.v3.RouteConfiguration>`
    // settings:
    //
    // * :ref:`cluster <envoy_v3_api_field_config.route.v3.RouteAction.cluster>` indicates the upstream cluster
    //   to route to.
    // * :ref:`weighted_clusters <envoy_v3_api_field_config.route.v3.RouteAction.weighted_clusters>`
    //   chooses a cluster randomly from a set of clusters with attributed weight.
    // * :ref:`cluster_header <envoy_v3_api_field_config.route.v3.RouteAction.cluster_header>` indicates which
    //   header in the request contains the target cluster.
    message DestinationCluster {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.DestinationCluster";
    }

    // The following descriptor entry is appended when a header contains a key that matches the
    // ``header_name``:
    //
    // .. code-block:: cpp
    //
    //   ("<descriptor_key>", "<header_value_queried_from_header>")
    message RequestHeaders {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.RequestHeaders";

      // The header name to be queried from the request headers. The header’s
      // value is used to populate the value of the descriptor entry for the
      // descriptor_key.
      string header_name = 1
          [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}];

      // The key to use in the descriptor entry.
      string descriptor_key = 2 [(validate.rules).string = {min_len: 1}];

      // Controls the behavior when the specified header is not present in the request.
      //
      // If set to ``false`` (default):
      //
      // * Envoy does **NOT** call the rate limiting service for this descriptor.
      // * Useful if the header is optional and you prefer to skip rate limiting when it's absent.
      //
      // If set to ``true``:
      //
      // * Envoy calls the rate limiting service but omits this descriptor if the header is missing.
      // * Useful if you want Envoy to enforce rate limiting even when the header is not present.
      //
      bool skip_if_absent = 3;
    }

    // The following descriptor entry is appended when a query parameter contains a key that matches the
    // ``query_parameter_name``:
    //
    // .. code-block:: cpp
    //
    //   ("<descriptor_key>", "<query_parameter_value_queried_from_query_parameter>")
    message QueryParameters {
      // The name of the query parameter to use for rate limiting. Value of this query parameter is used to populate
      // the value of the descriptor entry for the descriptor_key.
      string query_parameter_name = 1 [(validate.rules).string = {min_len: 1}];

      // The key to use when creating the rate limit descriptor entry. his descriptor key will be used to identify the
      // rate limit rule in the rate limiting service.
      string descriptor_key = 2 [(validate.rules).string = {min_len: 1}];

      // Controls the behavior when the specified query parameter is not present in the request.
      //
      // If set to ``false`` (default):
      //
      // * Envoy does **NOT** call the rate limiting service for this descriptor.
      // * Useful if the query parameter is optional and you prefer to skip rate limiting when it's absent.
      //
      // If set to ``true``:
      //
      // * Envoy calls the rate limiting service but omits this descriptor if the query parameter is missing.
      // * Useful if you want Envoy to enforce rate limiting even when the query parameter is not present.
      //
      bool skip_if_absent = 3;
    }

    // The following descriptor entry is appended to the descriptor and is populated using the
    // trusted address from :ref:`x-forwarded-for <config_http_conn_man_headers_x-forwarded-for>`:
    //
    // .. code-block:: cpp
    //
    //   ("remote_address", "<trusted address from x-forwarded-for>")
    message RemoteAddress {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.RemoteAddress";
    }

    // The following descriptor entry is appended to the descriptor and is populated using the
    // masked address from :ref:`x-forwarded-for <config_http_conn_man_headers_x-forwarded-for>`:
    //
    // .. code-block:: cpp
    //
    //   ("masked_remote_address", "<masked address from x-forwarded-for>")
    message MaskedRemoteAddress {
      // Length of prefix mask len for IPv4 (e.g. 0, 32).
      // Defaults to 32 when unset.
      // For example, trusted address from x-forwarded-for is ``192.168.1.1``,
      // the descriptor entry is ("masked_remote_address", "192.168.1.1/32");
      // if mask len is 24, the descriptor entry is ("masked_remote_address", "192.168.1.0/24").
      google.protobuf.UInt32Value v4_prefix_mask_len = 1 [(validate.rules).uint32 = {lte: 32}];

      // Length of prefix mask len for IPv6 (e.g. 0, 128).
      // Defaults to 128 when unset.
      // For example, trusted address from x-forwarded-for is ``2001:abcd:ef01:2345:6789:abcd:ef01:234``,
      // the descriptor entry is ("masked_remote_address", "2001:abcd:ef01:2345:6789:abcd:ef01:234/128");
      // if mask len is 64, the descriptor entry is ("masked_remote_address", "2001:abcd:ef01:2345::/64").
      google.protobuf.UInt32Value v6_prefix_mask_len = 2 [(validate.rules).uint32 = {lte: 128}];
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("generic_key", "<descriptor_value>")
    message GenericKey {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.GenericKey";

      // The value to use in the descriptor entry.
      string descriptor_value = 1 [(validate.rules).string = {min_len: 1}];

      // An optional key to use in the descriptor entry. If not set it defaults
      // to 'generic_key' as the descriptor key.
      string descriptor_key = 2;
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("header_match", "<descriptor_value>")
    message HeaderValueMatch {
      option (udpa.annotations.versioning).previous_message_type =
          "envoy.api.v2.route.RateLimit.Action.HeaderValueMatch";

      // The key to use in the descriptor entry. Defaults to ``header_match``.
      string descriptor_key = 4;

      // The value to use in the descriptor entry.
      string descriptor_value = 1 [(validate.rules).string = {min_len: 1}];

      // If set to true, the action will append a descriptor entry when the
      // request matches the headers. If set to false, the action will append a
      // descriptor entry when the request does not match the headers. The
      // default value is true.
      google.protobuf.BoolValue expect_match = 2;

      // Specifies a set of headers that the rate limit action should match
      // on. The action will check the request’s headers against all the
      // specified headers in the config. A match will happen if all the
      // headers in the config are present in the request with the same values
      // (or based on presence if the value field is not in the config).
      repeated HeaderMatcher headers = 3 [(validate.rules).repeated = {min_items: 1}];
    }

    // The following descriptor entry is appended when the
    // :ref:`dynamic metadata <well_known_dynamic_metadata>` contains a key value:
    //
    // .. code-block:: cpp
    //
    //   ("<descriptor_key>", "<value_queried_from_dynamic_metadata>")
    //
    // .. attention::
    //   This action has been deprecated in favor of the :ref:`metadata <envoy_v3_api_msg_config.route.v3.RateLimit.Action.MetaData>` action
    message DynamicMetaData {
      // The key to use in the descriptor entry.
      string descriptor_key = 1 [(validate.rules).string = {min_len: 1}];

      // Metadata struct that defines the key and path to retrieve the string value. A match will
      // only happen if the value in the dynamic metadata is of type string.
      type.metadata.v3.MetadataKey metadata_key = 2 [(validate.rules).message = {required: true}];

      // An optional value to use if ``metadata_key`` is empty. If not set and
      // no value is present under the metadata_key then no descriptor is generated.
      string default_value = 3;
    }

    // The following descriptor entry is appended when the metadata contains a key value:
    //
    // .. code-block:: cpp
    //
    //   ("<descriptor_key>", "<value_queried_from_metadata>")
    // [#next-free-field: 6]
    message MetaData {
      enum Source {
        // Query :ref:`dynamic metadata <well_known_dynamic_metadata>`
        DYNAMIC = 0;

        // Query :ref:`route entry metadata <envoy_v3_api_field_config.route.v3.Route.metadata>`
        ROUTE_ENTRY = 1;
      }

      // The key to use in the descriptor entry.
      string descriptor_key = 1 [(validate.rules).string = {min_len: 1}];

      // Metadata struct that defines the key and path to retrieve the string value. A match will
      // only happen if the value in the metadata is of type string.
      type.metadata.v3.MetadataKey metadata_key = 2 [(validate.rules).message = {required: true}];

      // An optional value to use if ``metadata_key`` is empty. If not set and
      // no value is present under the metadata_key then ``skip_if_absent`` is followed to
      // skip calling the rate limiting service or skip the descriptor.
      string default_value = 3;

      // Source of metadata
      Source source = 4 [(validate.rules).enum = {defined_only: true}];

      // Controls the behavior when the specified ``metadata_key`` is empty and ``default_value`` is not set.
      //
      // If set to ``false`` (default):
      //
      // * Envoy does **NOT** call the rate limiting service for this descriptor.
      // * Useful if the metadata is optional and you prefer to skip rate limiting when it's absent.
      //
      // If set to ``true``:
      //
      // * Envoy calls the rate limiting service but omits this descriptor if the ``metadata_key`` is empty and
      //   ``default_value`` is missing.
      // * Useful if you want Envoy to enforce rate limiting even when the metadata is not present.
      //
      bool skip_if_absent = 5;
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("query_match", "<descriptor_value>")
    message QueryParameterValueMatch {
      // The key to use in the descriptor entry. Defaults to ``query_match``.
      string descriptor_key = 4;

      // The value to use in the descriptor entry.
      string descriptor_value = 1 [(validate.rules).string = {min_len: 1}];

      // If set to true, the action will append a descriptor entry when the
      // request matches the headers. If set to false, the action will append a
      // descriptor entry when the request does not match the headers. The
      // default value is true.
      google.protobuf.BoolValue expect_match = 2;

      // Specifies a set of query parameters that the rate limit action should match
      // on. The action will check the request’s query parameters against all the
      // specified query parameters in the config. A match will happen if all the
      // query parameters in the config are present in the request with the same values
      // (or based on presence if the value field is not in the config).
      repeated QueryParameterMatcher query_parameters = 3
          [(validate.rules).repeated = {min_items: 1}];
    }

    oneof action_specifier {
      option (validate.required) = true;

      // Rate limit on source cluster.
      SourceCluster source_cluster = 1;

      // Rate limit on destination cluster.
      DestinationCluster destination_cluster = 2;

      // Rate limit on request headers.
      RequestHeaders request_headers = 3;

      // Rate limit on query parameters.
      QueryParameters query_parameters = 12;

      // Rate limit on remote address.
      RemoteAddress remote_address = 4;

      // Rate limit on a generic key.
      GenericKey generic_key = 5;

      // Rate limit on the existence of request headers.
      HeaderValueMatch header_value_match = 6;

      // Rate limit on dynamic metadata.
      //
      // .. attention::
      //   This field has been deprecated in favor of the :ref:`metadata <envoy_v3_api_field_config.route.v3.RateLimit.Action.metadata>` field
      DynamicMetaData dynamic_metadata = 7 [
        deprecated = true,
        (envoy.annotations.deprecated_at_minor_version) = "3.0",
        (envoy.annotations.disallowed_by_default) = true
      ];

      // Rate limit on metadata.
      MetaData metadata = 8;

      // Rate limit descriptor extension. See the rate limit descriptor extensions documentation.
      //
      // :ref:`HTTP matching input functions <arch_overview_matching_api>` are
      // permitted as descriptor extensions. The input functions are only
      // looked up if there is no rate limit descriptor extension matching
      // the type URL.
      //
      // [#extension-category: envoy.rate_limit_descriptors]
      core.v3.TypedExtensionConfig extension = 9;

      // Rate limit on masked remote address.
      MaskedRemoteAddress masked_remote_address = 10;

      // Rate limit on the existence of query parameters.
      QueryParameterValueMatch query_parameter_value_match = 11;
    }
  }

  message Override {
    // Fetches the override from the dynamic metadata.
    message DynamicMetadata {
      // Metadata struct that defines the key and path to retrieve the struct value.
      // The value must be a struct containing an integer "requests_per_unit" property
      // and a "unit" property with a value parseable to :ref:`RateLimitUnit
      // enum <envoy_v3_api_enum_type.v3.RateLimitUnit>`
      type.metadata.v3.MetadataKey metadata_key = 1 [(validate.rules).message = {required: true}];
    }

    oneof override_specifier {
      option (validate.required) = true;

      // Limit override from dynamic metadata.
      DynamicMetadata dynamic_metadata = 1;
    }
  }

  message HitsAddend {
    // Fixed number of hits to add to the rate limit descriptor.
    //
    // One of the ``number`` or ``format`` fields should be set but not both.
    google.protobuf.UInt64Value number = 1 [(validate.rules).uint64 = {lte: 1000000000}];

    // Substitution format string to extract the number of hits to add to the rate limit descriptor.
    // The same :ref:`format specifier <config_access_log_format>` as used for
    // :ref:`HTTP access logging <config_access_log>` applies here.
    //
    // .. note::
    //
    //   The format string must contains only single valid substitution field. If the format string
    //   not meets the requirement, the configuration will be rejected.
    //
    //   The substitution field should generates a non-negative number or string representation of
    //   a non-negative number. The value of the non-negative number should be less than or equal
    //   to 1000000000 like the ``number`` field. If the output of the substitution field not meet
    //   the requirement, this will be treated as an error and the current descriptor will be ignored.
    //
    // For example, the ``%BYTES_RECEIVED%`` format string will be replaced with the number of bytes
    // received in the request.
    //
    // One of the ``number`` or ``format`` fields should be set but not both.
    string format = 2 [(validate.rules).string = {prefix: "%" suffix: "%" ignore_empty: true}];
  }

  // Refers to the stage set in the filter. The rate limit configuration only
  // applies to filters with the same stage number. The default stage number is
  // 0.
  //
  // .. note::
  //
  //   The filter supports a range of 0 - 10 inclusively for stage numbers.
  //
  // .. note::
  //   This is not supported if the rate limit action is configured in the ``typed_per_filter_config`` like
  //   :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>` or
  //   :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>`, etc.
  google.protobuf.UInt32Value stage = 1 [(validate.rules).uint32 = {lte: 10}];

  // The key to be set in runtime to disable this rate limit configuration.
  //
  // .. note::
  //   This is not supported if the rate limit action is configured in the ``typed_per_filter_config`` like
  //   :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>` or
  //   :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>`, etc.
  string disable_key = 2;

  // A list of actions that are to be applied for this rate limit configuration.
  // Order matters as the actions are processed sequentially and the descriptor
  // is composed by appending descriptor entries in that sequence. If an action
  // cannot append a descriptor entry, no descriptor is generated for the
  // configuration. See :ref:`composing actions
  // <config_http_filters_rate_limit_composing_actions>` for additional documentation.
  repeated Action actions = 3 [(validate.rules).repeated = {min_items: 1}];

  // An optional limit override to be appended to the descriptor produced by this
  // rate limit configuration. If the override value is invalid or cannot be resolved
  // from metadata, no override is provided. See :ref:`rate limit override
  // <config_http_filters_rate_limit_rate_limit_override>` for more information.
  //
  // .. note::
  //   This is not supported if the rate limit action is configured in the ``typed_per_filter_config`` like
  //   :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>` or
  //   :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>`, etc.
  Override limit = 4;

  // An optional hits addend to be appended to the descriptor produced by this rate limit
  // configuration.
  //
  // .. note::
  //   This is only supported if the rate limit action is configured in the ``typed_per_filter_config`` like
  //   :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>` or
  //   :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>`, etc.
  HitsAddend hits_addend = 5;

  // If true, the rate limit request will be applied when the stream completes. The default value is false.
  // This is useful when the rate limit budget needs to reflect the response context that is not available
  // on the request path.
  //
  // For example, let's say the upstream service calculates the usage statistics and returns them in the response body
  // and we want to utilize these numbers to apply the rate limit action for the subsequent requests.
  // Combined with another filter that can set the desired addend based on the response (e.g. Lua filter),
  // this can be used to subtract the usage statistics from the rate limit budget.
  //
  // A rate limit applied on the stream completion is "fire-and-forget" by nature, and rate limit is not enforced by this config.
  // In other words, the current request won't be blocked when this is true, but the budget will be updated for the subsequent
  // requests based on the action with this field set to true. Users should ensure that the rate limit is enforced by the actions
  // applied on the request path, i.e. the ones with this field set to false.
  //
  // Currently, this is only supported by the HTTP global rate filter.
  bool apply_on_stream_done = 6;
}

// .. attention::
//
//   Internally, Envoy always uses the HTTP/2 ``:authority`` header to represent the HTTP/1 ``Host``
//   header. Thus, if attempting to match on ``Host``, match on ``:authority`` instead.
//
// .. attention::
//
//   To route on HTTP method, use the special HTTP/2 ``:method`` header. This works for both
//   HTTP/1 and HTTP/2 as Envoy normalizes headers. E.g.,
//
//   .. code-block:: json
//
//     {
//       "name": ":method",
//       "string_match": {
//         "exact": "POST"
//       }
//     }
//
// .. attention::
//   In the absence of any header match specifier, match will default to :ref:`present_match
//   <envoy_v3_api_field_config.route.v3.HeaderMatcher.present_match>`. i.e, a request that has the :ref:`name
//   <envoy_v3_api_field_config.route.v3.HeaderMatcher.name>` header will match, regardless of the header's
//   value.
//
//  [#next-major-version: HeaderMatcher should be refactored to use StringMatcher.]
// [#next-free-field: 15]
message HeaderMatcher {
  option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.route.HeaderMatcher";

  reserved 2, 3, 5;

  reserved "regex_match";

  // Specifies the name of the header in the request.
  string name = 1
      [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME strict: false}];

  // Specifies how the header match will be performed to route the request.
  oneof header_match_specifier {
    // If specified, header match will be performed based on the value of the header.
    // This field is deprecated. Please use :ref:`string_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.string_match>`.
    string exact_match = 4
        [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

    // If specified, this regex string is a regular expression rule which implies the entire request
    // header value must match the regex. The rule will not match if only a subsequence of the
    // request header value matches the regex.
    // This field is deprecated. Please use :ref:`string_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.string_match>`.
    type.matcher.v3.RegexMatcher safe_regex_match = 11
        [deprecated = true, (envoy.annotations.deprecated_at_minor_version) = "3.0"];

    // If specified, header match will be performed based on range.
    // The rule will match if the request header value is within this range.
    // The entire request header value must represent an integer in base 10 notation: consisting of
    // an optional plus or minus sign followed by a sequence of digits. The rule will not match if
    // the header value does not represent an integer. Match will fail for empty values, floating
    // point numbers or if only a subsequence of the header value is an integer.
    //
    // Examples:
    //
    // * For range [-10,0), route will match for header value -1, but not for 0, ``somestring``, 10.9,
    //   ``-1somestring``
    type.v3.Int64Range range_match = 6;

    // If specified as true, header match will be performed based on whether the header is in the
    // request. If specified as false, header match will be performed based on whether the header is absent.
    bool present_match = 7;

    // If specified, header match will be performed based on the prefix of the header value.
    // Note: empty prefix is not allowed, please use present_match instead.
    // This field is deprecated. Please use :ref:`string_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.string_match>`.
    //
    // Examples:
    //
    // * The prefix ``abcd`` matches the value ``abcdxyz``, but not for ``abcxyz``.
    string prefix_match = 9 [
      deprecated = true,
      (validate.rules).string = {min_len: 1},
      (envoy.annotations.deprecated_at_minor_version) = "3.0"
    ];

    // If specified, header match will be performed based on the suffix of the header value.
    // Note: empty suffix is not allowed, please use present_match instead.
    // This field is deprecated. Please use :ref:`string_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.string_match>`.
    //
    // Examples:
    //
    // * The suffix ``abcd`` matches the value ``xyzabcd``, but not for ``xyzbcd``.
    string suffix_match = 10 [
      deprecated = true,
      (validate.rules).string = {min_len: 1},
      (envoy.annotations.deprecated_at_minor_version) = "3.0"
    ];

    // If specified, header match will be performed based on whether the header value contains
    // the given value or not.
    // Note: empty contains match is not allowed, please use present_match instead.
    // This field is deprecated. Please use :ref:`string_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.string_match>`.
    //
    // Examples:
    //
    // * The value ``abcd`` matches the value ``xyzabcdpqr``, but not for ``xyzbcdpqr``.
    string contains_match = 12 [
      deprecated = true,
      (validate.rules).string = {min_len: 1},
      (envoy.annotations.deprecated_at_minor_version) = "3.0"
    ];

    // If specified, header match will be performed based on the string match of the header value.
    type.matcher.v3.StringMatcher string_match = 13;
  }

  // If specified, the match result will be inverted before checking. Defaults to false.
  //
  // Examples:
  //
  // * The regex ``\d{3}`` does not match the value ``1234``, so it will match when inverted.
  // * The range [-10,0) will match the value -1, so it will not match when inverted.
  bool invert_match = 8;

  // If specified, for any header match rule, if the header match rule specified header
  // does not exist, this header value will be treated as empty. Defaults to false.
  //
  // Examples:
  //
  // * The header match rule specified header "header1" to range match of [0, 10],
  //   :ref:`invert_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.invert_match>`
  //   is set to true and :ref:`treat_missing_header_as_empty <envoy_v3_api_field_config.route.v3.HeaderMatcher.treat_missing_header_as_empty>`
  //   is set to true; The "header1" header is not present. The match rule will
  //   treat the "header1" as an empty header. The empty header does not match the range,
  //   so it will match when inverted.
  // * The header match rule specified header "header2" to range match of [0, 10],
  //   :ref:`invert_match <envoy_v3_api_field_config.route.v3.HeaderMatcher.invert_match>`
  //   is set to true and :ref:`treat_missing_header_as_empty <envoy_v3_api_field_config.route.v3.HeaderMatcher.treat_missing_header_as_empty>`
  //   is set to false; The "header2" header is not present and the header
  //   matcher rule for "header2" will be ignored so it will not match.
  // * The header match rule specified header "header3" to a string regex match
  //   ``^$`` which means an empty string, and
  //   :ref:`treat_missing_header_as_empty <envoy_v3_api_field_config.route.v3.HeaderMatcher.treat_missing_header_as_empty>`
  //   is set to true; The "header3" header is not present.
  //   The match rule will treat the "header3" header as an empty header so it will match.
  // * The header match rule specified header "header4" to a string regex match
  //   ``^$`` which means an empty string, and
  //   :ref:`treat_missing_header_as_empty <envoy_v3_api_field_config.route.v3.HeaderMatcher.treat_missing_header_as_empty>`
  //   is set to false; The "header4" header is not present.
  //   The match rule for "header4" will be ignored so it will not match.
  bool treat_missing_header_as_empty = 14;
}

// Query parameter matching treats the query string of a request's :path header
// as an ampersand-separated list of keys and/or key=value elements.
// [#next-free-field: 7]
message QueryParameterMatcher {
  option (udpa.annotations.versioning).previous_message_type =
      "envoy.api.v2.route.QueryParameterMatcher";

  reserved 3, 4;

  reserved "value", "regex";

  // Specifies the name of a key that must be present in the requested
  // ``path``'s query string.
  string name = 1 [(validate.rules).string = {min_len: 1 max_bytes: 1024}];

  oneof query_parameter_match_specifier {
    // Specifies whether a query parameter value should match against a string.
    type.matcher.v3.StringMatcher string_match = 5 [(validate.rules).message = {required: true}];

    // Specifies whether a query parameter should be present.
    bool present_match = 6;
  }
}

// HTTP Internal Redirect :ref:`architecture overview <arch_overview_internal_redirects>`.
// [#next-free-field: 6]
message InternalRedirectPolicy {
  // An internal redirect is not handled, unless the number of previous internal redirects that a
  // downstream request has encountered is lower than this value.
  // In the case where a downstream request is bounced among multiple routes by internal redirect,
  // the first route that hits this threshold, or does not set :ref:`internal_redirect_policy
  // <envoy_v3_api_field_config.route.v3.RouteAction.internal_redirect_policy>`
  // will pass the redirect back to downstream.
  //
  // If not specified, at most one redirect will be followed.
  google.protobuf.UInt32Value max_internal_redirects = 1;

  // Defines what upstream response codes are allowed to trigger internal redirect. If unspecified,
  // only 302 will be treated as internal redirect.
  // Only 301, 302, 303, 307 and 308 are valid values. Any other codes will be ignored.
  repeated uint32 redirect_response_codes = 2 [(validate.rules).repeated = {max_items: 5}];

  // Specifies a list of predicates that are queried when an upstream response is deemed
  // to trigger an internal redirect by all other criteria. Any predicate in the list can reject
  // the redirect, causing the response to be proxied to downstream.
  // [#extension-category: envoy.internal_redirect_predicates]
  repeated core.v3.TypedExtensionConfig predicates = 3;

  // Allow internal redirect to follow a target URI with a different scheme than the value of
  // x-forwarded-proto. The default is false.
  bool allow_cross_scheme_redirect = 4;

  // Specifies a list of headers, by name, to copy from the internal redirect into the subsequent
  // request. If a header is specified here but not present in the redirect, it will be cleared in
  // the subsequent request.
  repeated string response_headers_to_copy = 5 [(validate.rules).repeated = {
    unique: true
    items {string {well_known_regex: HTTP_HEADER_NAME strict: false}}
  }];
}

// A simple wrapper for an HTTP filter config. This is intended to be used as a wrapper for the
// map value in
// :ref:`VirtualHost.typed_per_filter_config<envoy_v3_api_field_config.route.v3.VirtualHost.typed_per_filter_config>`,
// :ref:`Route.typed_per_filter_config<envoy_v3_api_field_config.route.v3.Route.typed_per_filter_config>`,
// or :ref:`WeightedCluster.ClusterWeight.typed_per_filter_config<envoy_v3_api_field_config.route.v3.WeightedCluster.ClusterWeight.typed_per_filter_config>`
// to add additional flags to the filter.
message FilterConfig {
  // The filter config.
  google.protobuf.Any config = 1;

  // If true, the filter is optional, meaning that if the client does
  // not support the specified filter, it may ignore the map entry rather
  // than rejecting the config.
  bool is_optional = 2;

  // If true, the filter is disabled in the route or virtual host and the ``config`` field is ignored.
  // See :ref:`route based filter chain <arch_overview_http_filters_route_based_filter_chain>`
  // for more details.
  //
  // .. note::
  //
  //   This field will take effect when the request arrive and filter chain is created for the request.
  //   If initial route is selected for the request and a filter is disabled in the initial route, then
  //   the filter will not be added to the filter chain.
  //   And if the request is mutated later and re-match to another route, the disabled filter by the
  //   initial route will not be added back to the filter chain because the filter chain is already
  //   created and it is too late to change the chain.
  //
  //   This field only make sense for the downstream HTTP filters for now.
  bool disabled = 3;
}
