router: allow propagating attempt count in header (#4536)

Signed-off-by: Snow Pettersen <snowp@squareup.com>

Mirrored from https://github.com/envoyproxy/envoy @ fdfa5bde3343372ad662a830da0bdc3aea806f4d

envoy/api/v2/route/route.proto

@@ -25,7 +25,7 @@ option (gogoproto.equal_all) = true;
 // 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: 14]
+// [#comment:next free field: 15]
 message VirtualHost {
   // The logical name of the virtual host. This is used when emitting certain
   // statistics but is not relevant for routing.
@@ -109,6 +109,16 @@ message VirtualHost {
   // 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;
+
+  // 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;
 }
 
 // A route is both a specification of how to match a request as well as an indication of what to do