Docker-实现MySQL主从复制

安装Docker

下载镜像并启动容器

下载镜像

root@ubuntu:~# docker pull mysql:5.7

启动master容器与slave容器

root@ubuntu:~# docker run --name master -p 3339:3306 -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
root@ubuntu:~# docker run --name slave -p 3340:3306 -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7

查看容器

root@ubuntu:~# docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                               NAMES
88fab660ae5f        mysql:5.7           "docker-entrypoint.s…"   32 seconds ago      Up 16 seconds       33060/tcp, 0.0.0.0:3340->3306/tcp   slave
c62e1b47c365        mysql:5.7           "docker-entrypoint.s…"   29 minutes ago      Up 13 minutes       33060/tcp, 0.0.0.0:3339->3306/tcp   master

配置master

进入master容器，对/etc/mysql/my.cnf进行编辑

root@ubuntu:~# docker exec -it master bash
root@c62e1b47c365:/# vi /etc/mysql/my.cnf

不出意外的话，你将会出现如下错误:

bash: vi: command not found

我们来安装一下vim：

root@c62e1b47c365:/# apt-get install vim

不出意外的话，你将会出现如下错误:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package vim

此时，我们可以更新一下apt-get，再进行安装

root@c62e1b47c365:/# apt-get update
root@c62e1b47c365:/# apt-get install vim

如果还出现问题，可以看下面的常见问题!!! 接下来，往/etc/mysql/my.cnf添加如下内容：

[mysqld]
server-id=100
# 开启二进制日志功能
log-bin=mysql-bin

保存文件，重启mysql，再重启容器：

root@c62e1b47c365:/# service mysql restart
[info] Stopping MySQL Community Server 5.7.30.
..root@ubuntu:~# docker container restart master

进入mysql

# 123456为上面启动容器中MYSQL_ROOT_PASSWORD环境变量配置的root密码
root@c62e1b47c365:/# mysql uroot -p123456
mysql>

创建slave用户，并赋予replication slave权限和replication client权限，用于主从库之间同步数据

mysql> use mysql;
mysql> create user 'slave'@'%' identified by '123456';
mysql> grant replication slave, replication client on *.* to 'slave'@'%';
mysql> flush privileges;

配置slave

和配置master一样，需要在/etc/mysql/my.cnf中添加如下配置：

[mysqld]
server-id=101
# 开启二进制日志功能，
log-bin=mysql-slave-bin
# relay_log配置中继日志
relay_log=edu-mysql-relay-bin

配置完之后，重启MySQL与容器

root@c62e1b47c365:/# service mysql restart
[info] Stopping MySQL Community Server 5.7.30.
..root@ubuntu:~# docker container restart slave

链接master与slave

在master中进入MySQL，执行show master status查看状态：

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 |     1418 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

在接下来的操作完成之前，请保证不要对master中的MySQL做任何操作，否则将引起状态的变化。

在slave中的MySQL中执行如下命令，链接master，如下：

mysql> change master to master_host='172.17.0.2', master_user='slave', master_password='123456', master_port=3306, master_log_file='mysql-bin.000001', master_log_pos=1418, master_connect_retry=30;

命令说明：

master_host: master的地址，指的是容器的独立IP。可以通过docker inspect --format '{{.NetworkSettings.IPAddress}}' master来查看
master_port: master的端口号，指的是容器的端口号
master_user: 用于数据同步的用户
master_password: 用于同步的用户的密码
master_log_file: 指定slave从哪个日志文件开始复制数据，即上文提到的File字段的值
master_log_pos: 从哪个position开始读，即上文中提到的Position字段的值
master_connect_retry: 如果连接失败，重试的时间间隔，单位为秒

此时我们在slave中的MySQL查看主从同步状态：

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 172.17.0.2
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 30
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 1418
               Relay_Log_File: edu-mysql-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: No
            Slave_SQL_Running: No
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 1418
              Relay_Log_Space: 154
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 0
                  Master_UUID: 
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

正常情况下，此时的Slave_IO_Running与Slave_SQL_Running都是NO，因为我们还没有开启主从复制过程。此时，我们执行一下start slave，再次查看一下状态：

mysql> start slave;
Query OK, 0 rows affected (0.03 sec)

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.0.2
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 30
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 1418
               Relay_Log_File: edu-mysql-relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 1418
              Relay_Log_Space: 531
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 100
                  Master_UUID: e101f6c0-ba7b-11ea-8e31-0242ac110002
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

此时，看到Slave_IO_Running与Slave_SQL_Running都是YES，说明主从复制已经开始，可以开始测试数据是否同步成功了

测试主从复制

我们在master容器中的MySQL创建一个数据库：

mysql> create database web;
Query OK, 1 row affected (0.01 sec)
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| web               |
+--------------------+
5 rows in set (0.00 sec)

此时，我们在来slave容器中的MySQL查看一下是否有这个数据库：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| web               |
+--------------------+
5 rows in set (0.00 sec)

如果有，就表明主从复制是成功的！！！

常见问题

Temporary failure resolving 'security.ubuntu.com’

解决办法：在/etc/docker/daemon.json文件中加入如下内容(文件不存在请新建该文件):

{
    "dns": [
        "114.114.114.114",
        "8.8.8.8"
    ]
}

然后再重启docker

Could not connect to deb.debian.org:80 (151.101.230.133), connection timed out

执行命令service docker restart重启docker

No query specified

出现问题的原因，SQL语句中的结尾加了个;，去掉就好了

Docker-实现MySQL主从复制

安装Docker

下载镜像并启动容器

配置master

配置slave

链接master与slave

测试主从复制

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