golang 如何读取环境变量的值

当几个golang 应用用的同一个数据库，譬如电商系统切开了， cart ， customer 应用都在本机，单独去配置文件填写，那么每个应用都要填写

可以通过linux的环境变量设置值，然后读取

github库包：github.com/coreos/pkg/flagutil

设置环境变量 vim /etc/profile

添加如下内容：

export GOROOT=/usr/local/go
export GOPATH=/root/go
export GOBIN=$GOPATH/bin
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

export TIX_AES_KEY=xxxxxxxxx
export TIX_NODE_NO=1
export TIX_AUTH_CRED=xxxxxxxxxx
export TIX_CLIENT_SECRET=123456
export TIX_XOR_KEY=666666
export TIX_CMS_DB_HOST=127.0.0.1
export TIX_CMS_DB_PORT=5433
export TIX_CMS_DB_USER=root
export TIX_CMS_DB_PASSWORD=123456
export TIX_CMS_DB_NAME=cms
export TIX_DB_HOST=127.0.0.1
export TIX_DB_PORT=5434
export TIX_DB_USER=root
export TIX_DB_PASSWORD=123456
export TIX_DB_NAME=newDb
export TIX_REDIS_MAIN=127.0.0.1:6380

export TIX_AMQP_URL=amqp://rabbitmq:rabbitmq@127.0.0.1:5672/
export TIX_PG_DSN_MASTER=postgres://cms:4passworddddd@dev.xxxx.to:5002/tix_new_db?sslmode=disable
export TIX_PG_DSN_SLAVE=postgres://cms:4passworddddd@dev.xxxx.to:5002/tix_new_db?sslmode=disable
export TIX_CLIENT_SECRET_CMS=66666666

然后 source /etc/profile 让添加的配置生效

golang中读取值

package repository

import (
	"context"
	"flag"
	"fmt"
	
	"xxxxxx/logging"
	"github.com/coreos/pkg/flagutil"
)

var (
	datasource     *DataSource
	dsnMaster      string
	dsnSlave       string
	psqlMaxCon     int
	psqlMaxIdleCon int
	redisMain      string
)

var log = logging.MustGetLogger()

func InitFactoryV2() error {
	flags := flag.NewFlagSet("user-auth", flag.PanicOnError)
	flags.IntVar(&psqlMaxCon, "DB_MAX_CON", 20, "PSQL db max connection")
	flags.IntVar(&psqlMaxIdleCon, "DB_MAX_IDLE_CON", 10, "PSQL db max idle connection")
	flags.StringVar(&dsnMaster, "PG_DSN_MASTER", "", "PG SQL data source name for master")
	flags.StringVar(&dsnSlave, "PG_DSN_SLAVE", "", "PG SQL data source name for slave")
	//redis
	flags.StringVar(&redisMain, "REDIS_MAIN", "", "redis main connection")

	err := flagutil.SetFlagsFromEnv(flags, "TIX")

	if err != nil {
		return err
	}

	if dsnMaster == "" {
		return fmt.Errorf("Unable to get environtment variable for dsn master, make sure you already set it!")
	}

	if dsnSlave == "" {
		return fmt.Errorf("Unable to get environtment variable for dsn Slave, make sure you already set it!")
	}

	if redisMain == "" {
		return fmt.Errorf("Unable to get environtment variable for redis main, make sure you already set it!")
	}

	dsn := fmt.Sprintf("%s;%s", dsnMaster, dsnSlave) //append master and slave(s)

	datasource = NewDBConnectionWithWrapper(dsn, psqlMaxCon, psqlMaxIdleCon)
	log.Info("Database Connection Started")

	err = OrderPreparedStatement(datasource)

	if err != nil {
		log.Error(err)
		return err
	}

	err = TicketPreparedStatement(datasource)

	if err != nil {
		log.Error(err)
		return err
	}

	log.Info("Prepared Statement Done")

	//initting redis
	InitRedis(redisMain)
	log.Info("redis initted")

	// init cache data
	InitCacheMovieMarathon(context.Background())
	log.Info("Init cache in-memory data done")

	return nil
}

也就是代码部分：

	flags := flag.NewFlagSet("user-auth", flag.PanicOnError)
	flags.IntVar(&psqlMaxCon, "DB_MAX_CON", 20, "PSQL db max connection")
	flags.IntVar(&psqlMaxIdleCon, "DB_MAX_IDLE_CON", 10, "PSQL db max idle connection")
	flags.StringVar(&dsnMaster, "PG_DSN_MASTER", "", "PG SQL data source name for master")
	flags.StringVar(&dsnSlave, "PG_DSN_SLAVE", "", "PG SQL data source name for slave")
	//redis
	flags.StringVar(&redisMain, "REDIS_MAIN", "", "redis main connection")

	err := flagutil.SetFlagsFromEnv(flags, "TIX")