// 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.extensions.formatter.cel.v3;

import "udpa/annotations/status.proto";

option java_package = "io.envoyproxy.envoy.extensions.formatter.cel.v3";
option java_outer_classname = "CelProto";
option java_multiple_files = true;
option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/formatter/cel/v3;celv3";
option (udpa.annotations.file_status).package_version_status = ACTIVE;

// [#protodoc-title: Formatter extension for printing CEL expressions]
// [#extension: envoy.formatter.cel]

// CEL formatter extension implements CEL command operator that evaluates configured
// symbolic Common Expression Language expressions to generate an access log.
//
// See :ref:`here <config_access_log>` for more information on access log configuration.

// %CEL(EXPRESSION):Z%
// Expressions are based on the set of Envoy :ref:`attributes <arch_overview_attributes>`.
// Expression errors are considered `-`. Z is an optional parameter denoting string
// truncation up to Z characters long.
//
// Examples:
//
// * ``%CEL(response.code)%``
// * ``%CEL(connection.mtls)%``
// * ``%CEL(request.headers['x-envoy-original-path']):10%``
// * ``%CEL(request.headers['x-log-mtls'] || request.url_path.contains('v1beta3'))%``

// Configuration for the CEL formatter.
//
// .. warning::
//   This extension is treated as built-in extension and will be enabled by default now.
//   It is unnecessary to configure this extension.
message Cel {
}
