docker_容器间的链接 link

分类于

使用link就是类似使用了容器的ip地址，无需知道其真实ip，使用link后的别名就可以知道

使用link连接容器

以 mysql 为 栗子

  1. 启动一个 mysql-server，详细参数可以参照说明文档：https://hub.docker.com/r/mysql/mysql-server/，设置密码，挂载数据库 等等
1
2
wilker@ubuntu:~$ docker pull mysql/mysql-server # 拉一个官方的镜像下来
wilker@ubuntu:~$ docker run --name=mysql_server11 -e MYSQL_ROOT_PASSWORD=123456 -d mysql/mysql-server # 启动容器，并设置 root 用户密码

  1. 进入 mysql_server11 容器中修改一下 root 用户可以访问的ip地址，默认是 localhost，别的ip是连不进来的，这里改成 任意 ip 都可以连进来（生产环境不能这样干）

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    wilker@ubuntu:~$ docker exec -it mysql_server11 mysql -uroot -p123456 # 进入容器的mysql服务
    mysql: [Warning] Using a password on the command line interface can be insecure.
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 4
    Server version: 5.7.18 MySQL Community Server (GPL)

    mysql> show databases; # 看下默认的数据库
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | mysql              |
    | performance_schema |
    | sys                |
    +--------------------+

    mysql> use mysql; # 使用 mysql 数据库
    Database changed
    mysql> select host,user from user where user='root';
    +-----------+------+
    | host      | user |
    +-----------+------+
    | localhost | root | # 默认只有 当前容器能用 root 用户连进来，要修改一下
    +-----------+------+
    1 row in set (0.00 sec)

    mysql> update user set host = '%'  where user ='root'; # 修改成 % 表示任意ip
    Query OK, 1 row affected (0.03 sec)
    Rows matched: 1  Changed: 1  Warnings: 0

    mysql> select host,user from user where user='root'; # 查看一下修改成功没
    +------+------+
    | host | user |
    +------+------+
    | %    | root |
    +------+------+
    1 row in set (0.00 sec)

    mysql> flush privileges; # 刷新权限使之生效
    Query OK, 0 rows affected (0.01 sec)

    mysql> exit; # 退出 mysql，然后自动退出容器
    Bye
    wilker@ubuntu:~$

  2. 去 docker hub 拉一个客户端下来，使用 link 连接 mysql_server11 容器，并使用别名 为 db

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    wilker@ubuntu:~$ docker pull imega/mysql-client # 拉 mysql 客户端镜像
    wilker@ubuntu:~$ docker run --name=mysql_client11 --link=mysql_server11:db -i -t imega/mysql-client mysql -h db -uroot -p123456 # -h 的值为 db，就是 mysql_server11 的ip别名
    Welcome to the MariaDB monitor.  Commands end with ; or \g.
    Your MySQL connection id is 14
    Server version: 5.7.18 MySQL Community Server (GPL)

    Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

    Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

    MySQL [(none)]> show databases; # 成功进入 mysql_server11 容器中的数据库
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | mysql              |
    | performance_schema |
    | sys                |
    +--------------------+
    4 rows in set (0.01 sec)

    MySQL [(none)]> exit;
    Bye

    • 退出客户端容器是容器也就变为 Exit 状态了，再次进入可以用 start 这个容器

      1
      2
      3
      4
      5
      6
      7
      8
      9
      10
      wilker@ubuntu:~$ docker start mysql_client11 -a 
      Welcome to the MariaDB monitor.  Commands end with ; or \g.
      Your MySQL connection id is 15
      Server version: 5.7.18 MySQL Community Server (GPL)

      Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

      Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

      MySQL [(none)]>

查看容器连接后的环境变量

还是用上面运行的 mysql 栗子

  • mysql_server11 的环境变量

    1
    2
    3
    4
    5
    6
    wilker@ubuntu:~$ docker exec mysql_server11 env
    PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    HOSTNAME=e3edaf102b4a
    MYSQL_ROOT_PASSWORD=123456
    PACKAGE_URL=https://repo.mysql.com/yum/mysql-5.7-community/docker/x86_64/mysql-community-server-minimal-5.7.18-1.el7.x86_64.rpm
    HOME=/root

  • mysql_client11 的环境变量，这里可以看到 mysql_server11 容器的环境变量

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    wilker@ubuntu:~$ docker exec mysql_client11 env  
    PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    HOSTNAME=db696da76b9c
    DB_PORT=tcp://172.17.0.2:3306
    DB_PORT_3306_TCP=tcp://172.17.0.2:3306
    DB_PORT_3306_TCP_ADDR=172.17.0.2
    DB_PORT_3306_TCP_PORT=3306
    DB_PORT_3306_TCP_PROTO=tcp
    DB_PORT_33060_TCP=tcp://172.17.0.2:33060
    DB_PORT_33060_TCP_ADDR=172.17.0.2
    DB_PORT_33060_TCP_PORT=33060
    DB_PORT_33060_TCP_PROTO=tcp
    DB_NAME=/mysql_client11/db
    DB_ENV_MYSQL_ROOT_PASSWORD=123456
    DB_ENV_PACKAGE_URL=https://repo.mysql.com/yum/mysql-5.7-community/docker/x86_64/mysql-community-server-minimal-5.7.18-1.el7.x86_64.rpm
    HOME=/root

    • 再看一下 hosts 文件, db 可以解析为 172.17.0.2，

      1
      2
      3
      4
      5
      6
      7
      8
      9
      wilker@ubuntu:~$ docker exec mysql_client11 cat /etc/hosts
      127.0.0.1       localhost
      ::1     localhost ip6-localhost ip6-loopback
      fe00::0 ip6-localnet
      ff00::0 ip6-mcastprefix
      ff02::1 ip6-allnodes
      ff02::2 ip6-allrouters
      172.17.0.2      db e3edaf102b4a mysql_server11
      172.17.0.3      db696da76b9c

参考资料