// Copyright 2021 The gRPC 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.

// Local copy of Envoy xDS proto file, used for testing only.

syntax = "proto3";

package envoy.type.matcher.v3;

// [#protodoc-title: Metadata matcher]

// MetadataMatcher provides a general interface to check if a given value is matched in
// :ref:`Metadata <envoy_v3_api_msg_config.core.v3.Metadata>`. It uses `filter` and `path` to retrieve the value
// from the Metadata and then check if it's matched to the specified value.
//
// For example, for the following Metadata:
//
// .. code-block:: yaml
//
//    filter_metadata:
//      envoy.filters.http.rbac:
//        fields:
//          a:
//            struct_value:
//              fields:
//                b:
//                  struct_value:
//                    fields:
//                      c:
//                        string_value: pro
//                t:
//                  list_value:
//                    values:
//                      - string_value: m
//                      - string_value: n
//
// The following MetadataMatcher is matched as the path [a, b, c] will retrieve a string value "pro"
// from the Metadata which is matched to the specified prefix match.
//
// .. code-block:: yaml
//
//    filter: envoy.filters.http.rbac
//    path:
//    - key: a
//    - key: b
//    - key: c
//    value:
//      string_match:
//        prefix: pr
//
// The following MetadataMatcher is matched as the code will match one of the string values in the
// list at the path [a, t].
//
// .. code-block:: yaml
//
//    filter: envoy.filters.http.rbac
//    path:
//    - key: a
//    - key: t
//    value:
//      list_match:
//        one_of:
//          string_match:
//            exact: m
//
// An example use of MetadataMatcher is specifying additional metadata in envoy.filters.http.rbac to
// enforce access control based on dynamic metadata in a request. See :ref:`Permission
// <envoy_v3_api_msg_config.rbac.v3.Permission>` and :ref:`Principal
// <envoy_v3_api_msg_config.rbac.v3.Principal>`.

// [#next-major-version: MetadataMatcher should use StructMatcher]
message MetadataMatcher {
}