gRPC-go

gRPC example with Golang

Reference

ex1(simple example)

ex2(simple tutorial)

ex3(server to server communiction)

Tutorial(ex2)

Install Protocol Buffer (for mac (local))

brew install protobuf

to be updated linux (ubuntu)

Install Plugins

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

GOPATH, Other settings are not described here

1. Define Protobuf Service

GetUser : GetUser returns user message by user_id
ListUser : ListUser returns all user Messages

// ex2/protos/v1/user/user.proto

syntax = "proto3";

package v1.user;

option go_package = "github.com/royroyee/gRPC-go/ex2/protos/v1/user";

service User {
  rpc GetUser(GetUserRequest) returns (GetUserResponse);
  rpc ListUser(ListUserRequest) returns (ListUserResponse);
}

message UserMessage {
  string user_id = 1;
  string name = 2;
  string phone_number = 3;
  int32 age = 4;
}

message GetUserRequest {
  string user_id = 1;
}

message GetUserResponse {
  UserMessage user_message = 1;
}

message ListUserRequest{}

message ListUserResponse {
  repeated UserMessage user_messages = 1;
}

2. Compile protofile

protoc -I=. \
	    --go_out . --go_opt paths=source_relative \
	    --go-grpc_out . --go-grpc_opt paths=source_relative \
	    protos/v1/user/user.proto

After compilation, the user.pb.go, user_grpc.pb.go file is created in the directory where the user.proto file is located.

3. Implement gRPC server with defined proto(user.pb,proto)

3.1 Database

If it's real microservice, get the data from the Database. but it's a simple example, so I'll use static variable

// ex2/data/user.go

import userpb "github.com/royroyee/gRPC-go/ex2/protos/v1/user"

var UserData = []*userpb.UserMessage{
    {   
        UserId:      "1",
        Name:        "kiny",
        PhoneNumber: "01012345678",
        Age:         21,
    },

    {
        UserId:      "2",
        Name:        "roy",
        PhoneNumber: "01012345678",
        Age:         24,
    },

    {
        UserId:      "3",
        Name:        "mini",
        PhoneNumber: "01012484428",
        Age:         13,
    },

    {
        UserId:      "4",
        Name:        "jenny",
        PhoneNumber: "01012731533",
        Age:         27,
    },

    {
        UserId:      "5",
        Name:        "jamin",
        PhoneNumber: "01024674568",
        Age:         31,
    },
}

total 5 users

3.2 gRPC Server

package main

import (
	"context"
	"github.com/royroyee/gRPC-go/ex2/data"
	userpb "github.com/royroyee/gRPC-go/ex2/protos/v1/user"
	"google.golang.org/grpc"
	"log"
	"net"
)

const portNumber = "9000"

type userServer struct {
	userpb.UserServer
}

// GetUser returns user message by user_id
func (s *userServer) GetUser(ctx context.Context, req *userpb.GetUserRequest) (*userpb.GetUserResponse, error) {
	userId := req.UserId

	var userMessage *userpb.UserMessage
	for _, u := range data.UserData {
		if u.UserId != userId {
			continue
		}
		userMessage = u
		break
	}
	return &userpb.GetUserResponse{
		UserMessage: userMessage,
	}, nil
}

// ListUsers returns all user Messages
func (s *userServer) ListUser(ctx context.Context, req *userpb.ListUserRequest) (*userpb.ListUserResponse, error) {
	userMessages := make([]*userpb.UserMessage, len(data.UserData))
	for i, u := range data.UserData {
		userMessages[i] = u
	}

	return &userpb.ListUserResponse{
		UserMessages: userMessages,
	}, nil
}

func main() {
	lis, err := net.Listen("tcp", ":"+portNumber)
	if err != nil {
		log.Fatalf("failed to listen : %v", err)
	}

	grpcServer := grpc.NewServer()
	userpb.RegisterUserServer(grpcServer, &userServer{})

	log.Printf("start gRPC server on %s port", portNumber)
	if err := grpcServer.Serve(lis); err != nil {
		log.Fatalf("failed to serve %s", err)
	}
}

4. Check it out

I'll use bloomrpc (gRPC gui tool)

mac(homebrew) : brew install --cask bloomrpc

4.1 Import proto file

how to use bloomrpc : https://github.com/bloomrpc/bloomrpc

4.2 gRPC server

go run main.go

royroyee / gRPC-go