How to Add gRPC Interceptors (Middleware) in Go

Add gRPC interceptors in Go by wrapping your server or client options with UnaryInterceptor or StreamInterceptor functions to handle cross-cutting concerns like logging and auth.

Add gRPC interceptors by wrapping your server or client options with grpc.UnaryServerInterceptor or grpc.StreamServerInterceptor functions.

func loggingInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
    log.Println("Request received")
    return handler(ctx, req)
}

server := grpc.NewServer(
    grpc.UnaryInterceptor(loggingInterceptor),
)

For streaming RPCs, use grpc.StreamInterceptor with a similar signature that wraps the grpc.StreamServer.

Interceptors are like toll booths for your gRPC requests that let you run code before or after the actual request is handled. You use them to add features like logging, authentication, or metrics without changing your main business logic. Just wrap your server setup with a function that handles the request and passes it along.