gRPC Go Proxy server
Build a transparent reverse proxy for gRPC targets that will make it easy to expose gRPC services over the internet. This includes:
- no needed knowledge of the semantics of requests exchanged in the call (independent rollouts)
- easy, declarative definition of backends and their mappings to frontends
- simple round-robin load balancing of inbound requests from a single connection to multiple backends
The project now exists as a proof of concept, with the key piece being the proxy package that
is a generic gRPC reverse proxy handler.
The package proxy contains a generic gRPC reverse proxy handler that allows a gRPC server to
not know about registered handlers or their data types. Please consult the docs, here's an exaple usage.
Defining a StreamDirector that decides where (if at all) to send the request
director = func(ctx context.Context, fullMethodName string) (*grpc.ClientConn, error) {
// Make sure we never forward internal services.
if strings.HasPrefix(fullMethodName, "/com.example.internal.") {
return nil, grpc.Errorf(codes.Unimplemented, "Unknown method")
}
md, ok := metadata.FromContext(ctx)
if ok {
// Decide on which backend to dial
if val, exists := md[":authority"]; exists && val[0] == "staging.api.example.com" {
// Make sure we use DialContext so the dialing can be cancelled/time out together with the context.
return grpc.DialContext(ctx, "api-service.staging.svc.local", grpc.WithCodec(proxy.Codec()))
} else if val, exists := md[":authority"]; exists && val[0] == "api.example.com" {
return grpc.DialContext(ctx, "api-service.prod.svc.local", grpc.WithCodec(proxy.Codec()))
}
}
return nil, grpc.Errorf(codes.Unimplemented, "Unknown method")
}Then you need to register it with a grpc.Server. The server may have other handlers that will be served
locally:
server := grpc.NewServer(
grpc.CustomCodec(proxy.Codec()),
grpc.UnknownServiceHandler(proxy.TransparentHandler(director)))
pb_test.RegisterTestServiceServer(server, &testImpl{})grpc-proxy is released under the Apache 2.0 license. See LICENSE.txt.