go-micro/examples/grpc-interop

gRPC Interop Example

This example shows that any standard gRPC client can call a go-micro service — no go-micro SDK required on the client side.

The server is a normal go-micro service using the gRPC transport. The client is a plain google.golang.org/grpc client with no go-micro imports.

How it works

go-micro's gRPC server uses a grpc.UnknownServiceHandler that catches all incoming requests and routes them by parsing the standard gRPC method path (/package.Service/Method). This means any language with gRPC support (Python, Java, Rust, etc.) can call go-micro services using generated protobuf stubs.

Running

Start the server:

cd examples/grpc-interop
go run ./server/

In another terminal, call it with the standard gRPC client:

cd examples/grpc-interop
go run ./client/ --name Alice
# Response: Hello Alice

Calling from other languages

Generate stubs from proto/greeter.proto in your language of choice and point them at localhost:50051. For example, with Python:

pip install grpcio-tools
python -m grpc_tools.protoc -Iproto --python_out=. --grpc_python_out=. proto/greeter.proto

import grpc
import greeter_pb2
import greeter_pb2_grpc

channel = grpc.insecure_channel("localhost:50051")
stub = greeter_pb2_grpc.GreeterStub(channel)

response = stub.Hello(greeter_pb2.HelloRequest(name="Alice"))
print(response.message)  # Hello Alice

Key points

• The go-micro server registers handlers via pb.RegisterGreeterHandler()
• The standard gRPC client uses stubs generated by protoc-gen-go-grpc
• Both share the same .proto file — that's the contract
• The server uses protobuf encoding on the wire, same as any gRPC service
• Service discovery (mDNS, consul, etc.) is only needed for go-micro-to-go-micro calls; direct gRPC clients connect by address

Regenerating proto stubs

protoc --go_out=. --go_opt=paths=source_relative \
       --go-grpc_out=. --go-grpc_opt=paths=source_relative \
       --micro_out=. --micro_opt=paths=source_relative \
       proto/greeter.proto

Requires protoc-gen-go, protoc-gen-go-grpc, and protoc-gen-micro.