GO GRPC BASIC

Requirements

Check other branch to step by step create project from 1/dev, 2/grpc-gateway, etc

Validate Go Installation

$ go version
go version go1.18.3 linux/amd64

Add GOPATH

add/edit to your ~/.bashrc or ~/.zshrc file

export GOPATH=/home/{your-user?}/go

dont forget to execute, to reload bash

source ~/.bashrc

to reload zsh

source ~/.zshrc

Validate GOPATH

$ echo $GOPATH
/home/aji/go

Start Project in Go

$ cd $GOPATH/src
$ mkdir -p github.com/ajikamaludin/go-grpc_basic 
$ cd github.com/ajikamaludin/go-grpc_basic 
$ go mod init github.com/ajikamaludin/go-grpc_basic
$ go mod tidy

Install Protoc

Linux : Download zip file, extract zip file to ~/.local/, add PATH ~/.local/bin please read documentation from this link for more detail information

https://grpc.io/docs/protoc-installation/

Validate Protoc Installation

$ protoc --version
libprotoc 3.21.2

Install Protoc Dependecy for Golang

# protoc-gen-go
go install github.com/golang/protobuf/protoc-gen-go@latest
# proto (optional, execute in project dir)
go get google.golang.org/protobuf/proto@latest
# protoc-gen-grpc-gateway
go install github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway@latest
# protoc-gen-swagger
go install github.com/grpc-ecosystem/grpc-gateway/protoc-gen-swagger@latest

Add PATH

add/edit to your ~/.bashrc or ~/.zshrc file

export PATH="$PATH:$GOPATH/bin"

Validate Protoc Dependency Golang Installation

~ ❯ ls $GOPATH/bin                                             
dlv         gopls    protoc-gen-go       protoc-gen-grpc-gateway 
go-outline  grpcurl  protoc-gen-go-grpc  protoc-gen-swagger

Start Project

Setup Project

• create proto dir
• create versioning dir and service dir health
• exec get-lib.sh in proto dir to download / get important library to use by health.proto usage is in compile proto file
• create proto file health.proto
• compile / generate proto with compile-proto.sh in proto dir

Setup config file

• create config.yaml
• create pkg dir , create versioning dir and create configs dir
• go get gopkg.in/yaml.v2 , is a lib for parsing yaml config file to struct
• create config.go file, implement New and other func
• create configs dir on root project , create configs.go, this is file that bundle or wrap any services or packages
• go get github.com/sirupsen/logrus, is a lib to show log on run
• implement New to configs.go file
• create main.go, implement to call config and log environtment read is ready
• test go run .

Implement Server GRPC

• create utils/constants dir in pkg/v1, to create global constants, implement EnvProduction, Successcode, SuccessDesc
• implement grpc service create api/v1/health service, create health.go as server service
• create api/v1/health/status.go as method implment from protobuf / pb file
• create router dir in root project
• create grpc.go in router dir and implement NewGRPCServer and register health api service
• go get github.com/soheilhy/cmux, TODO: what is for ?
• create router.go in router dir and implement IgnoreErr, this is for ignore error so can be safely ignore
• go get golang.org/x/sync/errgroup, TODO: what is for ?
• implement main.go to create grpc server from grpc.go with errgroup handler
• go run ., run server grpc
• go install github.com/fullstorydev/grpcurl/cmd/grpcurl@latest, this tool is
• test grpcurl -plaintext localhost:5566 list, to show list name of services
• test grpcurl -plaintext localhost:5566 list api.gogrpc.v1.health.HealthService, to show list name of service methods
• test grpcurl -plaintext localhost:5566 api.gogrpc.v1.health.HealthService.Status, to test method call in grpc
• result

{
    "success": true,
    "code": "0000",
    "desc": "SUCCESS"
}

• or test via postman , new -> grpc request -> Enter Server Url : localhost:5566 -> Import proto file / Select Method : Status -> Click Invoke

Implement gRPC-Gateway

ref https://github.com/grpc-ecosystem/grpc-gateway

• implement import "google/api/annotations.proto"; in proto file
• changes line below in all service methods for rest compile to rest

service HealthService {
    rpc Status(google.protobuf.Empty) returns (Response) {
        option (google.api.http) = {
           get: "/api/gogrpc/v1/health/status"
        };
    }
}

• re - compile / re - generate proto with execute compile-proto.sh in proto dir
• go mod tidy
• go get "github.com/gorilla/handlers" TODO: what is for ?
• create http.go in router dir and implement NewHTTPServer and register health api service
• register httpserver to main.go

g.Go(func() error { return router.NewHTTPServer(configs, logger) })

• go run . run grpc and http server
• test curl localhost:8080/api/v1/health/status, reponse

{
    "success":true,
    "code":"0000",
    "desc":"SUCCESS"
}

• GENERATE API DOCS:
• mkdir swagger
• cd proto
• ./gen-apidoc.sh, will be generated in swagger/docs.json
• register apidoc to http server in http.go implement

/////////

if configs.Config.Env != constants.EnvProduction {
	CreateSwagger(mux)
}

/////////

func CreateSwagger(gwmux *http.ServeMux) {
	gwmux.HandleFunc("/api/health/docs.json", func(w http.ResponseWriter, r *http.Request) {
		http.ServeFile(w, r, "swagger/docs.json")
	})
}

Implement DB_Connection (With PostgreSQL)

• Execute example.sql in db, you know how to do it
• add config.yaml with line below

postgres:
  host: 127.0.0.1
  port: 5432
  dbname: test
  username: postgres
  password: mysecretpassword

• changes pkg/v1/config/config.go to add new config line in config struct and and validateConfigData rule
• go get github.com/lib/pq, this is a lib for standart go lib database/sql to connect postgresql, usage in call

import (
    _ "github.com/lib/pq"
)
// ref : https://github.com/lib/pq

• create pkg/v1/postgres dir, create postgres.go file in there implement string conn and test connection
• create pkg/v1/utils/converter dir, create converter.go file in there, to convert camelcase to snake_case
• create pkg/v1/postgres/custom.main.go to implement all query to database table custom
• changes configs/configs.go to bundle pg connection
• how to use custom.main.go call function from api calldb, check api/v1/health/calldb.go

Example of call Other Rest API

• add new environtment to config.yaml add cert path
• changes pkg/v1/config/config.go to validate and add new environtment
• changes pkg/v1/utils/constants append method POST/GET/PUT/DELETE constant, JsonType Header, Hostname endpoint
• create pkg/v1/cert dir, create cert.go, this file is for handle Insecure ssl connection (self gen cert)
• create pkg/v1/requestapi dir, create requestapi.go, implement http call
• create services/v1/jsonplaceholder dir, create service name jsonplaceholder.go, implement any of endpoint http call from requestapi.go
• create new method from service health and implement call jsonplaceholder service from there, check api/v1/health/callapi.go

HTTP Custom Error Reponse

• create pgk/v1/utils/errors/errors.go, implement error handler for custom http
• register runtime Http error in http.go

runtime.HTTPError = errors.CustomHTTPError

File Logger

• goal : create log file for every action like , request / response from / to client, request / response from / to other api,
• go get github.com/lestrrat/go-file-rotatelogs, this lib for create rotate log file automated
• create pkg/v1/utils/logger/logger.go, implement logger function to write log to file
• implement logger for pkg/v1/requestapi/requestapi.go to log request and response api from other service
• implement logger for pkg/v1/utils/errors/errors.go to log any of error from our service
• implement logger for router/http.go to log response grpc rest api service
• go run .
• test call method callapi will generate hif log, custom-error generate error log, call rest will generate rest log

Jwt ( Json Web Tokens ) Auth

• add jwt configs to config.yaml, jwt: issuer: ajikamaludin, key: P@ssw0rd, type: Bearer
• changes pkg/v1/config/config.go add new config struct and validate config, [UPDATE] change New to GetInstance for singleton config

var lock = &sync.Mutex{}
var config *Config

func GetInstance() (*Config, error) {
	if config == nil {
		lock.Lock()
		defer lock.Unlock()
		config, err := New()
		if err != nil {
			return nil, err
		}
		return config, nil
	}
	return config, nil
}

• changes pkg/v1/utils/constants/constants.go to add new const for jwt token expired and refresh token expired
• go get github.com/dgrijalva/jwt-go, lib to handle jwt token in go
• create new pkg pkg/v1/jwt/jwt.go, implement Generate token and Claim token
• create new proto proto/v1/auth/auth.proto auth for login and register service, recompile sh compile-proto.sh [UPDATE]
• implement api/v1/auth/auth.go, api/v1/auth/login.go and api/v1/auth/register.go
• register new grpc service to grpc server

authpb.RegisterAuthServiceServer(grpcServer, auth.New(configs, logger))

• register new grp service to grpc gateay (http.go)

authpb.RegisterAuthServiceHandler,

• implement middleware in grpc server, for check jwtoken in every request , and add

    grpcServer := grpc.NewServer(
		grpc.UnaryInterceptor(
			grpc_middleware.ChainUnaryServer(
				authInterceptor,
			),
		),
	)

• test call login with any userid and password

curl -X POST -d '{"userId":"aji","password":"pass"}' http://localhost:8080/api/v1/auth/login

• result

{
    "success":true,
    "code":"0000",
    "desc":"SUCCESS",
    "auth":
        {
            "type":"Bearer",
            "access":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiYWppIiwiZXhwIjoxNjU4MTU2Njk5LCJpc3MiOiJiYW5rcmF5YSJ9.5o3b0twKzuqVzPtS68GMD6pw91m4JbCaJrg57iQw06A",
            "expiredPeriode":3600,
            "refresh":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiYWppIiwiaXNSZWZyZXNoIjp0cnVlLCJleHAiOjE2NTgxNTY2OTksImlzcyI6ImJhbmtyYXlhIn0.C8ZF9JFYWJIg3A0f9Ax2kWlPd1LJPeKZtDOSjX_KW6E"
        }
}

• use access token to access other resource / service - method