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GRPC:Go

lastmod 2025-11-24created 2025-11-197 edits

Quick start

Installing the compiler

Go plugins for the protocol compiler:

Install the protocol compiler plugins for Go using the following commands: 

go install google.golang.org/protobuf/cmd/protoc-gen-go@latest

Update your PATH so that the protoc compiler can find the plugins: 

export PATH="$PATH:$(go env GOPATH)/bin"

Get the example code 

git clone -b v1.77.0 --depth 1 https://github.com/grpc/grpc-go
cd grpc-go/examples/helloworld

Update the gRPC service 

syntax = "proto3";

option go_package = "google.golang.org/grpc/examples/helloworld/helloworld";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";

package helloworld;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

Regenerate gRPC code 

protoc --go_out=. --go_opt=paths=source_relative \
    --go-grpc_out=. --go-grpc_opt=paths=source_relative \
    helloworld/helloworld.proto

Server Code 

// Package main implements a server for Greeter service.
package main

import (
    "context"
    "flag"
    "fmt"
    "log"
    "net"

    "google.golang.org/grpc"
    pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

var (
    port = flag.Int("port", 50051, "The server port")
)

// server is used to implement helloworld.GreeterServer.
type server struct {
    pb.UnimplementedGreeterServer
}

// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(_ context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    log.Printf("Received: %v", in.GetName())
    return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}

func main() {
    flag.Parse()
    lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    s := grpc.NewServer()
    pb.RegisterGreeterServer(s, &server{})
    log.Printf("server listening at %v", lis.Addr())
    if err := s.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}

Client Code 

// Package main implements a client for Greeter service.
package main

import (
    "context"
    "flag"
    "log"
    "time"

    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials/insecure"
    pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
    defaultName = "world"
)

var (
    addr = flag.String("addr", "localhost:50051", "the address to connect to")
    name = flag.String("name", defaultName, "Name to greet")
)

func main() {
    flag.Parse()
    // Set up a connection to the server.
    conn, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    c := pb.NewGreeterClient(conn)

    // Contact the server and print out its response.
    ctx, cancel := context.WithTimeout(context.Background(), time.Second)
    defer cancel()
    r, err := c.SayHello(ctx, &pb.HelloRequest{Name: *name})
    if err != nil {
        log.Fatalf("could not greet: %v", err)
    }
    log.Printf("Greeting: %s", r.GetMessage())
}

Go Generated Code Guide 

go install google.golang.org/protobuf/cmd/protoc-gen-go@latest

protoc --proto_path=src --go_out=out --go_opt=paths=source_relative foo.proto bar/baz.proto

protoc-gen-go

protoc-gen-go is a plugin for the Google protocol buffer compiler that generates Go code. Install it by building this program and making it accessible in your PATH under the following name. 

protoc-gen-go

The 'go' suffix becomes part of the argument to the protocol compiler, so it can be invoked as follows. 

protoc --go_out=paths=source_relative:. path/to/file.proto

This generates Go bindings for the protocol buffers defined in file.proto. With that input, the output is written to the following location. 

path/to/file.pb.go

See also

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