I do not understand why I can not connect to mysql using docker compose golang mariadb/mysql multi container app

huangapple
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英文:

I do not understand why I can not connect to mysql using docker compose golang mariadb/mysql multi container app

问题

尝试创建一个使用Golang和MySQL的多容器应用程序，类似于Docker示例https://docs.docker.com/get-started/07_multi_container/。

我不明白为什么连接被拒绝。

dial tcp 127.0.0.1:3306: connect: connection refused

这是我的docker-compose.yaml文件：

  1. version: '3.7'
  3. services:
  4.   api:
  5.     # api服务正常启动，但在连接数据库时出现致命错误
  6.   maria-db:
  7.     image: mariadb:10-focal
  8.     container_name: s-maria-db
  9.     command: '--default-authentication-plugin=mysql_native_password'
  10.     restart: always
  11.     healthcheck:
  12.       test: ["CMD-SHEL", "mysqladmin ping -h 127.0.0.1 --password=secret --silent"]
  13.       interval: 3s
  14.       retries: 5
  15.       start_period: 30s
  16.     expose:
  17.       - "3306:3306"
  18.     # 设置一些环境变量来创建数据库
  19.     environment:
  20.       MYSQL_ROOT_PASSWORD: "secret"
  21.       MYSQL_DATABASE: "s_db"
  23.     # 挂载数据卷以确保不丢失数据
  24.     volumes:
  25.       - db-data:/var/lib/mysql
  27. volumes:
  28.   db-data:

这是我连接数据库的Go代码：

  1. func Connect() (*sql.DB, error) {
  2. 	db, err := sql.Open("mysql", "root:secret@/s_db")
  3. 	
  4. 	if err != nil {
  5. 		return nil, err
  6. 	}
  8. 	defer db.Close()
  10. 	pingErr := db.Ping()
  11. 	if pingErr != nil {
  12. 		return nil, pingErr
  13. 	}
  14. 	return db, nil
  15. }

我总是看到dial tcp 127.0.0.1:3306: connect: connection refused的错误。

我可以执行以下命令：

  1. docker exec -it s-maria-db bash
  2. .
  3. .
  4. .
  5. MariaDB [(none)]> show databases;
  6. +--------------------+
  7. | Database           |
  8. +--------------------+
  9. | information_schema |
  10. | s_db        |
  11. | mysql              |
  12. | performance_schema |
  13. | sys                |
  14. +--------------------+

并且可以看到数据库已正确配置，但我无法连接到它。

英文:

Attempting to create a golang mysql multi container app. Similar to docker example https://docs.docker.com/get-started/07_multi_container/

I do not understand why connection is refused.

dial tcp 127.0.0.1:3306: connect: connection refused

Here is my docker-compose.yaml

  1. version: '3.7'
  3. services:
  4.   api:
  5.     # api service starts ok but fatal error at db connection
  6.   maria-db:
  7.     image: mariadb:10-focal
  8.     container_name: s-maria-db
  9.     command: '--default-authentication-plugin=mysql_native_password'
  10.     restart: always
  11.     healthcheck:
  12.       test: ["CMD-SHEL", "mysqladmin ping -h 127.0.0.1 --password=secret --silent"]
  13.       interval: 3s
  14.       retries: 5
  15.       start_period: 30s
  16.     expose:
  17.       - "3306:3306"
  18.     # setting some env vars to create the DB
  19.     environment:
  20.       MYSQL_ROOT_PASSWORD: "secret"
  21.       MYSQL_DATABASE: "s_db"
  23.     # we mount a data volume to make sure we don't lose data
  24.     volumes:
  25.       - db-data:/var/lib/mysql
  27. volumes:
  28.   db-data:

Here is my go-code to connect to db

  1. func Connect() (*sql.DB, error) {
  2. 	db, err := sql.Open("mysql", "root:secret@/s_db")
  3. 	
  4. 	if err != nil {
  5. 		return nil, err
  6. 	}
  8. 	defer db.Close()
  10. 	pingErr := db.Ping()
  11. 	if pingErr != nil {
  12. 		return nil, pingErr
  13. 	}
  14. 	return db, nil
  15. }

I always see dial tcp 127.0.0.1:3306: connect: connection refused

I can

  1. docker exec -it s-maria-db bash
  2. .
  3. .
  4. .
  5. MariaDB [(none)]> show databases;
  6. +--------------------+
  7. | Database           |
  8. +--------------------+
  9. | information_schema |
  10. | s_db        |
  11. | mysql              |
  12. | performance_schema |
  13. | sys                |
  14. +--------------------+

and see the db is configured correctly , but I can never connect to it.

答案1

得分: 2

尝试使用容器的名称进行连接，因为Docker Compose使用Docker网络。这样可以通过容器的名称作为网络别名进行连接。

  1. func Connect() (*sql.DB, error) {
  2.     db, err := sql.Open("mysql", "root:secret@tcp(s-maria-db)/s_db")
  3.     
  4.     if err != nil {
  5.         return nil, err
  6.     }
  8.     defer db.Close()
  10.     pingErr := db.Ping()
  11.     if pingErr != nil {
  12.         return nil, pingErr
  13.     }
  14.     return db, nil
  15. }
英文:

try to connect using container's name hence docker composer uses docker network. That allows you to connect via container's name as a network alias.

  1. func Connect() (*sql.DB, error) {
  2. db, err := sql.Open("mysql", "root:secret@tcp(s-maria-db)/s_db")
  4. if err != nil {
  5.     return nil, err
  6. }
  8. defer db.Close()
  10. pingErr := db.Ping()
  11. if pingErr != nil {
  12.     return nil, pingErr
  13. }
  14. return db, nil

}

答案2

得分: 2

此外，更新的代码如下：

  1. for i := 0; i < 60; i++ {
  2. 	if err := db.Ping(); err == nil {
  3. 		fmt.Print("我们已连接！")
  4. 		break
  5. 	}
  6. 	time.Sleep(time.Second)
  7. }

代码来源：https://github.com/docker/awesome-compose/blob/master/nginx-golang-mysql/backend/main.go

英文:

Additionally updated go with

  1. 	for i := 0; i &lt; 60; i++ {
  2. 		if err := db.Ping(); err == nil {
  3. 			fmt.Print(&quot;We are connected!&quot;)
  4. 			break
  5. 		}
  6. 		time.Sleep(time.Second)
  7. 	}

as seen https://github.com/docker/awesome-compose/blob/master/nginx-golang-mysql/backend/main.go

huangapple
  • 本文由 发表于 2023年3月31日 00:59:22
  • 转载请务必保留本文链接：https://go.coder-hub.com/75891043.html
  • docker
  • go
  • mariadb
  • mysql
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