data-plane-api/envoy/api/v2/route/route.proto

syntax = "proto3";

package envoy.api.v2.route;
option java_package = "io.envoyproxy.envoy.api.v2.route";
option go_package = "route";
option java_generic_services = true;

import "envoy/api/v2/core/base.proto";
import "envoy/type/range.proto";

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

import "validate/validate.proto";
import "gogoproto/gogo.proto";

option (gogoproto.equal_all) = true;

// [#protodoc-title: HTTP route]
// * 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.
// [#comment:next free field: 17]
message VirtualHost {
  // 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_bytes = 1];

  // A list of domains (host/authority header) that will be matched to this
  // virtual host. Wildcard hosts are supported in the form of ``*.foo.com`` or
  // ``*-bar.foo.com``.
  //
  // .. 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``.
  //   Additionally, a special entry ``*`` is allowed which will match any
  //   host/authority header. 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.
  repeated string domains = 2 [(validate.rules).repeated .min_items = 1];

  // The list of routes that will be matched, in order, for incoming requests.
  // The first route that matches will be used.
  repeated Route routes = 3 [(gogoproto.nullable) = false];

  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;
  }

  // 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;

  // 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_api_msg_route.Route` and before headers from the
  // enclosing :ref:`envoy_api_msg_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.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;

  // 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_api_msg_route.Route` and before headers from the
  // enclosing :ref:`envoy_api_msg_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.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;

  // Indicates that the virtual host has a CORS policy.
  CorsPolicy cors = 8;

  reserved 9;

  // The per_filter_config field can be used to provide virtual host-specific
  // configurations for filters. The key should match the filter name, such as
  // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
  // specific; see the :ref:`HTTP filter documentation <config_http_filters>`
  // for if and how it is utilized.
  map<string, google.protobuf.Struct> per_filter_config = 12 [deprecated = true];

  // The per_filter_config field can be used to provide virtual host-specific
  // configurations for filters. The key should match the filter name, such as
  // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
  // specific; see the :ref:`HTTP filter documentation <config_http_filters>`
  // for if and how it is utilized.
  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_api_field_config.filter.http.router.v2.Router.suppress_envoy_headers>` flag.
  bool include_request_attempt_count = 14;

  // 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;
}

// 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_api_msg_route.HeaderMatcher>`.
// [#comment:next free field: 14]
message Route {
  // Route matching parameters.
  RouteMatch match = 1 [(validate.rules).message.required = true, (gogoproto.nullable) = false];

  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;
  }

  // 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.router*.
  core.Metadata metadata = 4;

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

  reserved 6;

  // The per_filter_config field can be used to provide route-specific
  // configurations for filters. The key should match the filter name, such as
  // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
  // specific; see the :ref:`HTTP filter documentation <config_http_filters>` for
  // if and how it is utilized.
  map<string, google.protobuf.Struct> per_filter_config = 8 [deprecated = true];

  // The per_filter_config field can be used to provide route-specific
  // configurations for filters. The key should match the filter name, such as
  // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
  // specific; see the :ref:`HTTP filter documentation <config_http_filters>` for
  // if and how it is utilized.
  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_api_msg_route.VirtualHost` and
  // :ref:`envoy_api_msg_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.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;

  // 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_api_msg_route.VirtualHost` and
  // :ref:`envoy_api_msg_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.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;
}

// Compared to the :ref:`cluster <envoy_api_field_route.RouteAction.cluster>` field that specifies a
// single upstream cluster as the target of a request, the :ref:`weighted_clusters
// <envoy_api_field_route.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.
// [#comment:next free field: 11]
message WeightedCluster {
  message ClusterWeight {
    // Name of the upstream cluster. The cluster must exist in the
    // :ref:`cluster manager configuration <config_cluster_manager>`.
    string name = 1 [(validate.rules).string.min_bytes = 1];

    // An integer between 0 and :ref:`total_weight
    // <envoy_api_field_route.WeightedCluster.total_weight>`. 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 add up to the total_weight, which defaults to 100.
    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.MetadataMatch <envoy_api_field_route.RouteAction.metadata_match>`, with values
    // here taking precedence. The filter name should be specified as *envoy.lb*.
    core.Metadata metadata_match = 3;

    // Specifies a list of headers to be added to requests when this cluster is selected
    // through the enclosing :ref:`envoy_api_msg_route.RouteAction`.
    // Headers specified at this level are applied before headers from the enclosing
    // :ref:`envoy_api_msg_route.Route`, :ref:`envoy_api_msg_route.VirtualHost`, and
    // :ref:`envoy_api_msg_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.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_api_msg_route.RouteAction`.
    repeated string request_headers_to_remove = 9;

    // Specifies a list of headers to be added to responses when this cluster is selected
    // through the enclosing :ref:`envoy_api_msg_route.RouteAction`.
    // Headers specified at this level are applied before headers from the enclosing
    // :ref:`envoy_api_msg_route.Route`, :ref:`envoy_api_msg_route.VirtualHost`, and
    // :ref:`envoy_api_msg_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.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_api_msg_route.RouteAction`.
    repeated string response_headers_to_remove = 6;

    reserved 7;

    // The per_filter_config field can be used to provide weighted cluster-specific
    // configurations for filters. The key should match the filter name, such as
    // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
    // specific; see the :ref:`HTTP filter documentation <config_http_filters>`
    // for if and how it is utilized.
    map<string, google.protobuf.Struct> per_filter_config = 8 [deprecated = true];

    // The per_filter_config field can be used to provide weighted cluster-specific
    // configurations for filters. The key should match the filter name, such as
    // *envoy.buffer* for the HTTP buffer filter. Use of this field is filter
    // specific; see the :ref:`HTTP filter documentation <config_http_filters>`
    // for if and how it is utilized.
    map<string, google.protobuf.Any> typed_per_filter_config = 10;
  }

  // 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, which must be greater than 0. Defaults to 100.
  google.protobuf.UInt32Value total_weight = 3 [(validate.rules).uint32.gte = 1];

  // 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;
}

message RouteMatch {
  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. The regex grammar is defined `here
    // <http://en.cppreference.com/w/cpp/regex/ecmascript>`_.
    //
    // Examples:
    //
    // * The regex */b[io]t* matches the path */bit*
    // * The regex */b[io]t* matches the path */bot*
    // * The regex */b[io]t* does not match the path */bite*
    // * The regex */b[io]t* does not match the path */bit/bot*
    string regex = 3 [(validate.rules).string.max_bytes = 1024];
  }

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

  reserved 5;

  // 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.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.
  repeated QueryParameterMatcher query_parameters = 7;

  message GrpcRouteMatchOptions {
  }

  // 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;
}

// [#comment:next free field: 11]
message CorsPolicy {
  // Specifies the origins that will be allowed to do CORS requests.
  //
  // An origin is allowed if either allow_origin or allow_origin_regex match.
  repeated string allow_origin = 1;

  // Specifies regex patterns that match allowed origins.
  //
  // An origin is allowed if either allow_origin or allow_origin_regex match.
  repeated string allow_origin_regex = 8 [(validate.rules).repeated .items.string.max_bytes = 1024];

  // 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 if CORS is enabled. Defaults to true. Only effective on route.
    //
    // .. attention::
    //
    //   **This field is deprecated**. Set the
    //   :ref:`filter_enabled<envoy_api_field_route.CorsPolicy.filter_enabled>` field instead.
    google.protobuf.BoolValue enabled = 7 [deprecated = true];

    // Specifies if CORS is enabled.
    //
    // More information on how this can be controlled via runtime can be found
    // :ref:`here <cors-runtime>`.
    //
    // .. note::
    //
    //   This field defaults to 100/:ref:`HUNDRED
    //   <envoy_api_enum_type.FractionalPercent.DenominatorType>`.
    core.RuntimeFractionalPercent filter_enabled = 9;
  }

  // Specifies if CORS policies are evaluated and tracked when filter is off but
  // does not enforce any policies.
  //
  // More information on how this can be controlled via runtime can be found
  // :ref:`here <cors-runtime>`.
  //
  // .. note::
  //
  //   This field defaults to 100/:ref:`HUNDRED
  //   <envoy_api_enum_type.FractionalPercent.DenominatorType>`.
  core.RuntimeFractionalPercent shadow_enabled = 10;
}

// [#comment:next free field: 27]
message RouteAction {
  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_bytes = 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.
    string cluster_header = 2 [(validate.rules).string.min_bytes = 1];

    // 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;
  }

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

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

  // 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_api_field_route.RouteAction.weighted_clusters>`, metadata will be merged, with values
  // provided there taking precedence. The filter name should be specified as *envoy.lb*.
  core.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.
  //
  // .. attention::
  //
  //   Pay careful attention to the use of trailing slashes in the
  //   :ref:`route's match <envoy_api_field_route.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_api_msg_route.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;

  oneof host_rewrite_specifier {
    // Indicates that during forwarding, the host header will be swapped with
    // this value.
    string host_rewrite = 6;

    // 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*. Setting this to true with other cluster
    // types has no effect.
    google.protobuf.BoolValue auto_host_rewrite = 7;
  }

  // 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.
  //
  // .. 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 [(gogoproto.stdduration) = true];

  // 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_api_field_config.filter.network.http_connection_manager.v2.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_api_field_route.RouteAction.timeout>`, which provides an upper bound
  // on the upstream response time; :ref:`idle_timeout
  // <envoy_api_field_route.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.
  google.protobuf.Duration idle_timeout = 24
      [(validate.rules).duration.gt = {}, (gogoproto.stdduration) = true];

  // 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;

  // 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*.
  message RequestMirrorPolicy {
    // Specifies the cluster that requests will be mirrored to. The cluster must
    // exist in the cluster manager configuration.
    string cluster = 1 [(validate.rules).string.min_bytes = 1];

    // If not specified, all requests to the target cluster will be mirrored. If
    // specified, Envoy will lookup the runtime key to get the % of requests to
    // mirror. Valid values are from 0 to 10000, allowing for increments of
    // 0.01% of requests to be mirrored. If the runtime key is specified in the
    // configuration but not present in runtime, 0 is the default and thus 0% of
    // requests will be mirrored.
    //
    // .. attention::
    //
    //   **This field is deprecated**. Set the
    //   :ref:`runtime_fraction
    //   <envoy_api_field_route.RouteAction.RequestMirrorPolicy.runtime_fraction>` field instead.
    string runtime_key = 2 [deprecated = true];

    // If both :ref:`runtime_key
    // <envoy_api_field_route.RouteAction.RequestMirrorPolicy.runtime_key>` and this field are 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.
    //
    // .. note::
    //
    //   Parsing this field is implemented such that the runtime key's data may be represented
    //   as a :ref:`FractionalPercent <envoy_api_msg_type.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 is behaviour is different to that of the deprecated `runtime_key` field,
    //   where the implicit denominator is 10000.
    core.RuntimeFractionalPercent runtime_fraction = 3;
  }

  // Indicates that the route has a request mirroring policy.
  RequestMirrorPolicy request_mirror_policy = 10;

  // Optionally specifies the :ref:`routing priority <arch_overview_http_routing_priority>`.
  // [#comment:TODO(htuch): add (validate.rules).enum.defined_only = true once
  // https://github.com/lyft/protoc-gen-validate/issues/42 is resolved.]
  core.RoutingPriority priority = 11;

  // [#not-implemented-hide:]
  repeated core.HeaderValueOption request_headers_to_add = 12 [deprecated = true];

  // [#not-implemented-hide:]
  repeated core.HeaderValueOption response_headers_to_add = 18 [deprecated = true];

  // [#not-implemented-hide:]
  repeated string response_headers_to_remove = 19 [deprecated = 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_api_field_route.VirtualHost.rate_limits>` are not applied to the
  // request.
  google.protobuf.BoolValue include_vh_rate_limits = 14;

  // Specifies the route's hashing policy if the upstream cluster uses a hashing :ref:`load balancer
  // <arch_overview_load_balancing_types>`.
  message HashPolicy {
    message 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_bytes = 1];
    }

    // 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 {
      // 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_bytes = 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 [(gogoproto.stdduration) = true];

      // 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;
    }

    message ConnectionProperties {
      // Hash on source IP address.
      bool source_ip = 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;
    }

    // The flag that shortcircuits 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;
  }

  // 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;

  reserved 16;
  reserved 22;

  // Indicates that the route has a CORS policy.
  CorsPolicy cors = 17;

  reserved 21;

  // 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_api_field_route.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_api_field_route.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.
  google.protobuf.Duration max_grpc_timeout = 23 [(gogoproto.stdduration) = true];

  // 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_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.upgrade_configs>`
  // but does not affect any custom filter chain specified there.
  message UpgradeConfig {
    // 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;
    // Determines if upgrades are available on this route. Defaults to true.
    google.protobuf.BoolValue enabled = 2;
  };
  repeated UpgradeConfig upgrade_configs = 25;

  // Configures :ref:`internal redirect <arch_overview_internal_redirects>` behavior.
  enum InternalRedirectAction {
    PASS_THROUGH_INTERNAL_REDIRECT = 0;
    HANDLE_INTERNAL_REDIRECT = 1;
  }
  InternalRedirectAction internal_redirect_action = 26;
}

// HTTP retry :ref:`architecture overview <arch_overview_http_routing_retry>`.
message RetryPolicy {
  // 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;

  // Specifies a non-zero upstream timeout per retry 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_api_field_route.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 [(gogoproto.stdduration) = true];

  message RetryPriority {
    string name = 1 [(validate.rules).string.min_bytes = 1];
    oneof config_type {
      google.protobuf.Struct config = 2 [deprecated = true];

      google.protobuf.Any typed_config = 3;
    }
  }

  // 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;

  message RetryHostPredicate {
    string name = 1 [(validate.rules).string.min_bytes = 1];
    oneof config_type {
      google.protobuf.Struct config = 2 [deprecated = true];

      google.protobuf.Any typed_config = 3;
    }
  }

  // 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;

  // 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;
}

message RedirectAction {
  // 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;
  // 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.
    string path_redirect = 2;

    // 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_api_field_route.RouteAction.prefix_rewrite>`.
    string prefix_rewrite = 5;
  }

  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;
  }

  // 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 {
  // Specifies the HTTP response status to be returned.
  uint32 status = 1 [(validate.rules).uint32 = {gte: 100, lt: 600}];

  // 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_api_msg_route.Route`, :ref:`envoy_api_msg_RouteConfiguration` or
  //   :ref:`envoy_api_msg_route.VirtualHost`.
  core.DataSource body = 2;
}

message 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_bytes = 1];
}

// 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_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 {
  // Specifies a regex pattern to use for matching requests. The entire path of the request
  // must match the regex. The regex grammar used is defined `here
  // <http://en.cppreference.com/w/cpp/regex/ecmascript>`_.
  //
  // Examples:
  //
  // * The regex */rides/\d+* matches the path */rides/0*
  // * The regex */rides/\d+* matches the path */rides/123*
  // * The regex */rides/\d+* does not match the path */rides/123/456*
  string pattern = 1 [(validate.rules).string = {min_bytes: 1, max_bytes: 1024}];

  //  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_bytes = 1];

  // Optionally specifies the HTTP method to match on. For example GET, PUT,
  // etc.
  // [#comment:TODO(htuch): add (validate.rules).enum.defined_only = true once
  // https://github.com/lyft/protoc-gen-validate/issues/42 is resolved.]
  core.RequestMethod method = 3;
}

// Global rate limiting :ref:`architecture overview <arch_overview_rate_limit>`.
message RateLimit {
  // 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.
  google.protobuf.UInt32Value stage = 1 [(validate.rules).uint32.lte = 10];

  // The key to be set in runtime to disable this rate limit configuration.
  string disable_key = 2;

  message 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 {
    }

    // 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_api_msg_RouteConfiguration>`
    // settings:
    //
    // * :ref:`cluster <envoy_api_field_route.RouteAction.cluster>` indicates the upstream cluster
    //   to route to.
    // * :ref:`weighted_clusters <envoy_api_field_route.RouteAction.weighted_clusters>`
    //   chooses a cluster randomly from a set of clusters with attributed weight.
    // * :ref:`cluster_header <envoy_api_field_route.RouteAction.cluster_header>` indicates which
    //   header in the request contains the target cluster.
    message 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 {
      // 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_bytes = 1];

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

    // 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 {
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("generic_key", "<descriptor_value>")
    message GenericKey {
      // The value to use in the descriptor entry.
      string descriptor_value = 1 [(validate.rules).string.min_bytes = 1];
    }

    // The following descriptor entry is appended to the descriptor:
    //
    // .. code-block:: cpp
    //
    //   ("header_match", "<descriptor_value>")
    message HeaderValueMatch {
      // The value to use in the descriptor entry.
      string descriptor_value = 1 [(validate.rules).string.min_bytes = 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];
    }

    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 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;
    }
  }

  // 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];
}

// .. 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",
//       "exact_match": "POST"
//     }
//
// .. attention::
//   In the absence of any header match specifier, match will default to :ref:`present_match
//   <envoy_api_field_route.HeaderMatcher.present_match>`. i.e, a request that has the :ref:`name
//   <envoy_api_field_route.HeaderMatcher.name>` header will match, regardless of the header's
//   value.
//
message HeaderMatcher {
  // Specifies the name of the header in the request.
  string name = 1 [(validate.rules).string.min_bytes = 1];

  reserved 2; // value deprecated by :ref:`exact_match
              // <envoy_api_field_route.HeaderMatcher.exact_match>`

  reserved 3; // regex deprecated by :ref:`regex_match
              // <envoy_api_field_route.HeaderMatcher.regex_match>`

  // 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.
    string exact_match = 4;

    // 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. The regex grammar used in the value field is defined
    // `here <http://en.cppreference.com/w/cpp/regex/ecmascript>`_.
    //
    // Examples:
    //
    // * The regex *\d{3}* matches the value *123*
    // * The regex *\d{3}* does not match the value *1234*
    // * The regex *\d{3}* does not match the value *123.456*
    string regex_match = 5 [(validate.rules).string.max_bytes = 1024];

    // 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"
    envoy.type.Int64Range range_match = 6;

    // If specified, header match will be be performed based on whether the header is in the
    // request.
    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.
    //
    // Examples:
    //
    // * The prefix *abcd* matches the value *abcdxyz*, but not for *abcxyz*.
    string prefix_match = 9 [(validate.rules).string.min_bytes = 1];

    // 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.
    //
    // Examples:
    //
    // * The suffix *abcd* matches the value *xyzabcd*, but not for *xyzbcd*.
    string suffix_match = 10 [(validate.rules).string.min_bytes = 1];
  }

  // 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;
}

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

  // Specifies the value of the key. If the value is absent, a request
  // that contains the key in its query string will match, whether the
  // key appears with a value (e.g., "?debug=true") or not (e.g., "?debug")
  string value = 3;

  // Specifies whether the query parameter value is a regular expression.
  // Defaults to false. The entire query parameter value (i.e., the part to
  // the right of the equals sign in "key=value") must match the regex.
  // E.g., the regex "\d+$" will match "123" but not "a123" or "123a".
  google.protobuf.BoolValue regex = 4;
}