mwitkow/ grpc-proxy

Shell

gRPC

golang

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About the developer

mwitkow

564 Stars

121 Forks

Apache License 2.0

25 Commits

23 Opened issues

Description

gRPC proxy is a Go reverse proxy that allows for rich routing of gRPC calls with minimum overhead.

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gRPC Proxy

Name: grpc-proxy
Brand: grpc-proxy
SKU: //mwitkow/grpc-proxy
Rating: 3.128 (564 reviews)

gRPC Go Proxy server

Project Goal

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.

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

go
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{})

License

grpc-proxy

is released under the Apache 2.0 license. See LICENSE.txt.