在Docker中测试MySQL 8.x 主从复制
最近在学习MySQL的主从复制,就闲来无事在docker里面练练手,记录一下学习过程.
Source Replication配置
拉镜像
拉默认最新版本的MySQL即可
创建docker network
保证Source/Replica可以成功同步的前提是网络得通,那么第一步就是重新创建一个单独的docker network,当然默认的也可以,但是我不太喜欢大锅饭.
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docker network create mysql_bridge #创建MySQL专用的docker网络
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创建容器
我文件夹下面的mysql_01_conf和mysql_02_conf的MySQL配置文件,照抄即可,能自己写更好.
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# mysql_01_conf/source.cnf
[mysqld]
server-id=1 #唯一ID
log_bin=mysql-bin#开启binlog
binlog_format=ROW#行级复制
gtid_mode=ON#开启GTID
enforce_gtid_consistency=ON #强制GTID一致性
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注意哈!文件必须是.cnf结尾的.
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# mysql_02_conf/replica.cnf
[mysqld]
server-id=2 #唯一ID 必须和其他的server-id不一样
relay-log=relay-bin #中继日志
gtid_mode=ON #启用gtid模式,不用老的binlog+pos
enforce_gtid_consistency=ON #强制GTID一致性
read_only=ON #防止误写
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我默认是只持久化配置文件,那些/var/lib/mysql我就没有同步了,毕竟是测试数据都不重要,但是生产环境还是要做好数据持久化的,bind mount或者 volume mount都可以.
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docker run -d --rm -v $PWD/mysql_01_conf:/etc/mysql/conf.d --name mysql_01 --network mysql_bridge -e MYSQL_ROOT_PASSWORD=123456 mysql #这个用来做主数据库
docker run -d --rm -v $PWD/mysql_02_conf:/etc/mysql/conf.d --name mysql_02 --network mysql_bridge -e MYSQL_ROOT_PASSWORD=123456 mysql #这个用来做从数据库
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主库(Source)
先进容器
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docker exec -it mysql_01 mysql -uroot -p
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create user 'repl'@'%' identified by '123456';#创建一个用于同步的用户
grant replication slave on *.* to 'repl'@'%';#给予所有数据库权限
flush privileges;
show binary log status;#查看一下
+------------------+----------+--------------+------------------+------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+------------------------------------------+
| mysql-bin.000003 | 198 | | | 39e8fe3d-5913-11f1-a31e-3af1c8c7e730:1-5 |
+------------------+----------+--------------+------------------+------------------------------------------+
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从库(Replication)
先进容器
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docker exec -it mysql_02 mysql -uroot -p
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change replication source to
source_host='mysql_01',#docker创建的第一个容器名称即可
source_user='repl',
source_password='123456',
source_auto_position=1;#开启GTID自动同步,必须要开的
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start replica;#开始主从备份
show replica status\G #查看一下,看到 Replica_IO_Running: Yes,Replica_SQL_Running: Yes 就是正常成功同步啦
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完整步骤
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# mysql_01 Source
docker exec -it mysql_01 mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 9.7.0 MySQL Community Server - GPL
Copyright (c) 2000, 2026, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
mysql>
mysql>
mysql> show binary logs;
+------------------+-----------+-----------+
| Log_name | File_size | Encrypted |
+------------------+-----------+-----------+
| mysql-bin.000001 | 181 | No |
| mysql-bin.000002 | 2997943 | No |
| mysql-bin.000003 | 198 | No |
+------------------+-----------+-----------+
3 rows in set (0.002 sec)
mysql> show binary log status;
+------------------+----------+--------------+------------------+------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+------------------------------------------+
| mysql-bin.000003 | 198 | | | 39e8fe3d-5913-11f1-a31e-3af1c8c7e730:1-5 |
+------------------+----------+--------------+------------------+------------------------------------------+
1 row in set (0.001 sec)
mysql> create user 'repl'@'%' identified by '123456';
Query OK, 0 rows affected (0.076 sec)
mysql> grant replication slave on *.* to 'repl'@'%';
Query OK, 0 rows affected (0.017 sec)
mysql> flush privileges;
Query OK, 0 rows affected, 1 warning (0.018 sec)
mysql> show binary log status;
+------------------+----------+--------------+------------------+------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+------------------------------------------+
| mysql-bin.000003 | 899 | | | 39e8fe3d-5913-11f1-a31e-3af1c8c7e730:1-8 |
+------------------+----------+--------------+------------------+------------------------------------------+
1 row in set (0.001 sec)
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# mysql_02 Replication
docker exec -it mysql_02 mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 9.7.0 MySQL Community Server - GPL
Copyright (c) 2000, 2026, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> change replication source to
-> source_host='mysql_01',
-> source_user='repl',
-> source_password='123456',
-> source_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.090 sec)
mysql> start replica;
Query OK, 0 rows affected (0.068 sec)
mysql> show replica status\G
*************************** 1. row ***************************
Replica_IO_State: Waiting for source to send event
Source_Host: mysql_01
Source_User: repl
Source_Port: 3306
Connect_Retry: 60
Source_Log_File: mysql-bin.000003
Read_Source_Log_Pos: 899
Relay_Log_File: relay-bin.000003
Relay_Log_Pos: 1116
Relay_Source_Log_File: mysql-bin.000003
Replica_IO_Running: Yes #
Replica_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_Source_Log_Pos: 899
Relay_Log_Space: 2999300
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Source_SSL_Allowed: Yes
Source_SSL_CA_File:
Source_SSL_CA_Path:
Source_SSL_Cert:
Source_SSL_Cipher:
Source_SSL_Key:
Seconds_Behind_Source: 0
Source_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Source_Server_Id: 1
Source_UUID: 39e8fe3d-5913-11f1-a31e-3af1c8c7e730
Source_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Replica_SQL_Running_State: Replica has read all relay log; waiting for more updates
Source_Retry_Count: 10
Source_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Source_SSL_Crl:
Source_SSL_Crlpath:
Retrieved_Gtid_Set: 39e8fe3d-5913-11f1-a31e-3af1c8c7e730:1-8
Executed_Gtid_Set: 39e8fe3d-5913-11f1-a31e-3af1c8c7e730:1-8,
48d2ce30-5913-11f1-aad7-7ae654cbeca4:1-5
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Source_TLS_Version:
Source_public_key_path:
Get_Source_public_key: 0
Network_Namespace:
1 row in set (0.002 sec)
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至此结束了,操作还是很简单的,主要还是要理解Mysql主从同步的原理.
验证
其他知识
主从复制核心日志
| Source |
Replication |
| Binlog |
relay log |
从库同步数据原理:
从库有两个重要的线程:IO和SQL,
- IO线程负责拉取主库binlog,然后写入本地relay log
- SQL线程执行relay log才是真正的数据同步
主从延迟:
show replica status\G查看,有时候发现Seconds_Behind_Source:60,落后主库60s,这个是正常的,有可能是
- 大事务,一次几百万行数据
- SQL慢,从库执行不过来
- 锁等待,卡住
- 单线程复制,老版本问题
- 磁盘差,IO跟不上
- 也可能是刻意配置的
binlog三种格式
STATEMENT
记录sql,执行SQL,哪都好,问题是:uuid(),now(),rand()大概率(99.99… …%)不一样
ROW
记录数据变化,最安全,生产环境主流。
MIXED
我不知道谁在用
生产环境重要配置
半同步复制
异步(默认):主库写完直接返回,风险点是:主库突然挂了,从库可能没同步到.
建议至少一个从库收到才返回,更安全.
常见命令:
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stop replica; #停止复制
start replica; #启动复制
reset replica all;#重置复制,生产环境勿用,会导致事务报错,清空复制信息。
show variables like '%gtid%';#查看GTID
show binary logs;#查看binlog
show relaylog events;#查看relaylog
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主从复制的模式
基于位置Position
是传统模式,例如：mysql-bin.000001 + pos=157,
很多老系统还在用。
基于GTID
MySQL8 主流方案,
生产环境都GTID。
