http: add support for removing request headers. (#4431)

While there, move header modification in some tests from
route action level (deprecated in #3838) to route level.

*Risk Level*: Low
*Testing*: bazel test //test/...
*Docs Changes*: Added
*Release Notes*: Added

Fixes #4249.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 6ce3e1f45005c37e4a951470ee0bcf0381738e76

envoy/api/v2/core/health_check.proto

@@ -73,6 +73,7 @@ message HealthCheck {
     }
   }
 
+  // [#comment:next free field: 9]
   message HttpHealthCheck {
     // The value of the host header in the HTTP health check request. If
     // left empty (default value), the name of the cluster this health check is associated
@@ -100,6 +101,10 @@ message HealthCheck {
     // <config_http_conn_man_headers_custom_request_headers>`.
     repeated core.HeaderValueOption request_headers_to_add = 6;
 
+    // Specifies a list of HTTP headers that should be removed from each request that is sent to the
+    // health checked cluster.
+    repeated string request_headers_to_remove = 8;
+
     // If set, health checks will be made using http/2.
     bool use_http2 = 7;
   }

envoy/api/v2/rds.proto

@@ -40,6 +40,7 @@ service RouteDiscoveryService {
   }
 }
 
+// [#comment:next free field: 9]
 message RouteConfiguration {
   // The name of the route configuration. For example, it might match
   // :ref:`route_config_name
@@ -76,6 +77,10 @@ message RouteConfiguration {
   // <config_http_conn_man_headers_custom_request_headers>`.
   repeated core.HeaderValueOption request_headers_to_add = 6;
 
+  // Specifies a list of HTTP headers that should be removed from each request
+  // routed by the HTTP connection manager.
+  repeated string request_headers_to_remove = 8;
+
   // An optional boolean that specifies whether the clusters that the route
   // table refers to will be validated by the cluster manager. If set to true
   // and a route refers to a non-existent cluster, the route table will not

envoy/api/v2/route/route.proto

@@ -25,6 +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]
 message VirtualHost {
   // The logical name of the virtual host. This is used when emitting certain
   // statistics but is not relevant for routing.
@@ -81,6 +82,10 @@ message VirtualHost {
   // <config_http_conn_man_headers_custom_request_headers>`.
   repeated core.HeaderValueOption request_headers_to_add = 7;
 
+  // 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
@@ -113,6 +118,7 @@ message VirtualHost {
 //
 //   Envoy supports routing on HTTP method via :ref:`header matching
 //   <envoy_api_msg_route.HeaderMatcher>`.
+// [#comment:next free field: 13]
 message Route {
   // Route matching parameters.
   RouteMatch match = 1 [(validate.rules).message.required = true, (gogoproto.nullable) = false];
@@ -157,6 +163,10 @@ message Route {
   // <config_http_conn_man_headers_custom_request_headers>`.
   repeated core.HeaderValueOption request_headers_to_add = 9;
 
+  // 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
@@ -176,6 +186,7 @@ message Route {
 // 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: 10]
 message WeightedCluster {
   message ClusterWeight {
     // Name of the upstream cluster. The cluster must exist in the
@@ -204,6 +215,10 @@ message WeightedCluster {
     // <config_http_conn_man_headers_custom_request_headers>`.
     repeated core.HeaderValueOption request_headers_to_add = 4;
 
+    // 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