Support FilterChain level Post xDS Hook about gateway HOT 2 OPEN

So what you're looking for is to update the EnvoyGatewayExtension interface and add an additional method?

Something like:

service EnvoyGatewayExtension {
    rpc PostRouteModify (PostRouteModifyRequest) returns (PostRouteModifyResponse) {};
    rpc PostVirtualHostModify(PostVirtualHostModifyRequest) returns (PostVirtualHostModifyResponse) {};
    rpc PostHTTPListenerModify(PostHTTPListenerModifyRequest) returns (PostHTTPListenerModifyResponse) {};
    rpc PostTranslateModify(PostTranslateModifyRequest) returns (PostTranslateModifyResponse) {};

    // PostFilterChainModify provides a way for extensions to modify a filter chains generated by Envoy Gateway 
    // before it is finalized. 
    rpc PostFilterChainModify(PostFilterChainModifyRequest) returns (PostFilterChainModifyResponse) {};
}

The semantics could be that before PostHTTPListenerModify is called, then PostFilterChainModify is called for each of the available filter chains including the default filter chain.

from gateway.

So what you're looking for is to update the EnvoyGatewayExtension interface and add an additional method?

Yes, additional method is used to control filter chain translated from Gateway listener, because xDS listener may have multiple filter chains.

The semantics could be that before PostHTTPListenerModify is called, then PostFilterChainModify is called for each of the available filter chains including the default filter chain.

It'll be better if PostHTTPListenerModify is called just after xDS listener is created. And when each filter chain is created from Gateway listener, PostFilterChainModify is called, then insert into xDS listener.

Because if N Gateway listeners will be translated into single xDS listener, there will be N filter chains in the final xDS listener, inserted one by one. Until translation is done, PostHTTPListenerModify will be called N times, the i (1 <= i <= N ) round call carry i filter chains. It has additional data transfer overhead if N is bigger.

from gateway.