前面幾篇已完成基礎(chǔ)環(huán)境的搭建和一個flask極簡項(xiàng)目的發(fā)布.在實(shí)際使用當(dāng)中, 數(shù)據(jù)庫備份也顯得很重要.因?yàn)槭褂玫氖莇ocker版mysql(5.6). 本文將基于此環(huán)境, 實(shí)戰(zhàn)講解docker版mysql的主從復(fù)制.
使用MySQL主從復(fù)制的目的在于:
- 主從服務(wù)器設(shè)置的穩(wěn)健性得以提升. 如果主服務(wù)器發(fā)生故障, 可以把本來作為備份的從服務(wù)器提升為主服務(wù)器.
- 在主從服務(wù)器上分開處理用戶的請求, 可獲得更短的響應(yīng)時間.
- 用從服務(wù)器做數(shù)據(jù)備份而不會占用主服務(wù)器的系統(tǒng)資源.
MySQL主從復(fù)制
場景描述
在 第二篇: 搭建環(huán)境 -- Centos7(64位)云主機(jī)部署Python Flask項(xiàng)目實(shí)戰(zhàn)系列 中已經(jīng)創(chuàng)建有一個docker版的mysql 5.6. 這里將已經(jīng)創(chuàng)建的mysql容器作為主容器, 再創(chuàng)建一個容器作為從容器.
- 主mysql服務(wù)器: 名為my-mysql的docker容器
- 從mysql服務(wù)器: 需要新建容器
主容器my-mysql已經(jīng)在運(yùn)行中.
創(chuàng)建mysql從容器(mysql-bk)
復(fù)制主容器的映射文件夾
[root@localhost local]# cp -r mysql mysql_bk
創(chuàng)建從容器, 并命名為: mysql-bk,并連接主容器my-mysql
[root@localhost mysql] docker run --restart=always -p 3305:3306 --name mysql-bk --link my-mysql:my-mysql -v $PWD/conf/my.cnf:/etc/mysql/my.cnf -v $PWD/logs:/logs -v $PWD/data:/mysql_data -e MYSQL_ROOT_PASSWORD=12345 -d mysql:5.6
這里將docker主機(jī)的3305端口映射到從容器mysql-bk. 意即: 在宿主機(jī)器中使用3305端口來連接從容器mysql-bk.
查看運(yùn)行狀態(tài)
[root@huanaCentos mysql_bk]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4781d5c516b8 mysql:5.6 "docker-entrypoint.sh" 29 seconds ago Up 28 seconds 0.0.0.0:3305->3306/tcp mysql-bk
615c9b2e4fa3 mysql:5.6 "docker-entrypoint.sh" About an hour ago Up 53 minutes 0.0.0.0:3306->3306/tcp my-mysql
4dbea194a61c redis:3.2 "docker-entrypoint.sh" 5 days ago Up 25 hours 0.0.0.0:6379->6379/tcp my-redis
3bdee31c2ddc mongo:3.4 "docker-entrypoint.sh" 5 days ago Up 25 hours 0.0.0.0:27017->27017/tcp my-mongo
docker link
Docker通過下述兩種方法把子容器里的信息暴露給父容器:
- 環(huán)境變量
- 更新 /etc/host 文件
先來看下docker設(shè)定的環(huán)境變量。 在mysql-bk容器里， 運(yùn)行 env 命令 列出所有的環(huán)境變量。
[root@localhost mysql_bk]# docker exec -it mysql-bk bash
root@4781d5c516b8:/# env
HOSTNAME=4781d5c516b8
MYSQL_VERSION=5.6.37-1debian8
MY_MYSQL_NAME=/mysql-bk/my-mysql
MY_MYSQL_ENV_MYSQL_MAJOR=5.6
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/
MY_MYSQL_PORT=tcp://172.17.0.3:3306
MY_MYSQL_PORT_3306_TCP_PORT=3306
MY_MYSQL_PORT_3306_TCP_ADDR=172.17.0.3
MY_MYSQL_PORT_3306_TCP=tcp://172.17.0.3:3306
MY_MYSQL_PORT_3306_TCP_PROTO=tcp
SHLVL=1
HOME=/root
MY_MYSQL_ENV_MYSQL_VERSION=5.6.37-1debian8
MY_MYSQL_ENV_GOSU_VERSION=1.7
MYSQL_MAJOR=5.6
MY_MYSQL_ENV_MYSQL_ROOT_PASSWORD=12345
GOSU_VERSION=1.7
MYSQL_ROOT_PASSWORD=12345
_=/usr/bin/env
root@4781d5c516b8:/#
可以看到Docker創(chuàng)建了一些對于我們使用my-mysql很有用的環(huán)境變量。 每一個變量都以 MY-MYSQL 開頭. 你可以使用這些環(huán)境 變量來配置你的應(yīng)用程序來連接 my-mysql里的數(shù)據(jù)庫。 連接是安全的、私有的 僅限于 mysql-bk 和 my-mysql之間。
除了環(huán)境變量之外Docker會把父容器的IP添加到子容器的/etc/hosts里。
root@4781d5c516b8:/# 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
172.17.0.3 my-mysql 615c9b2e4fa3
172.17.0.5 4781d5c516b8
此時, mysql-bk容器中, 可以直接ping通my-mysql容器了.
root@4781d5c516b8:/# ping my-mysql
PING my-mysql (172.17.0.3): 56 data bytes
64 bytes from 172.17.0.3: icmp_seq=0 ttl=64 time=0.082 ms
64 bytes from 172.17.0.3: icmp_seq=1 ttl=64 time=0.071 ms
64 bytes from 172.17.0.3: icmp_seq=2 ttl=64 time=0.083 ms
主從復(fù)制(無用戶數(shù)據(jù)的情況)
1. 修改配置
在主容器my-mysql的配置文件的[mysqld]欄添加以下兩行:
log-bin = mysql-bin
server-id = 1
thread_concurrency = 2
thread_concurrency 與線程有關(guān)
thread_concurrency應(yīng)設(shè)為CPU核數(shù)的2倍. 比如有一個雙核的CPU, 那thread_concurrency 的應(yīng)該為4; 2個雙核的cpu, thread_concurrency的值應(yīng)為8.
在從容器mysql-bk的配置文件的[mysqld]欄添加以下兩行:
log-bin = mysql-bin
server-id = 2
thread_concurrency = 2
重新運(yùn)行下這兩個容器:
[root@localhost mysql_bk]# docker restart mysql-bk
mysql-bk
[root@localhost mysql_bk]# docker restart my-mysql
my-mysql
2. 主容器上進(jìn)行操作
(1). 創(chuàng)建一個用戶用來同步數(shù)據(jù)
mysql> GRANT REPLICATION SLAVE ON *.* to 'backup'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
(2). 查看主mysql容器數(shù)據(jù)庫狀態(tài)
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 120 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
mysql>
記下File及Position的值, 在后面進(jìn)行從容器操作的時候需要使用.
如果沒有查到數(shù)據(jù), 請檢查my.cnf配置是否正確.
3. 在從容器mysql-bk中執(zhí)行同步
(1).執(zhí)行同步SQL語句
mysql> change master to master_host='172.17.0.1', master_user='backup',
-> master_password='123456',
-> master_log_file='mysql-bin.000001',
-> master_log_pos=120,
-> master_port=3306;
Query OK, 0 rows affected, 2 warnings (0.02 sec)
master_host值也可為: my-mysql, 因?yàn)樵趍ysql-bk容器本地/etc/hosts文件中已經(jīng)有該容器的地址解析了.
(2).啟動slave同步功能
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
(3).主從同步檢查
執(zhí)行show slave status/G來檢查從服務(wù)器的同步情況, 一個正常的輸出結(jié)果應(yīng)該如下面的形式:
mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 172.17.0.1
Master_User: backup
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 120
Relay_Log_File: mysqld-relay-bin.000002
Relay_Log_Pos: 283
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: 120
Relay_Log_Space: 457
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: 1
Master_UUID: ac7410b4-8553-11e7-bd97-0242ac110003
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 the slave I/O thread to update it
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
1 row in set (0.00 sec)
mysql>
主從復(fù)制(有用戶數(shù)據(jù)的情況)
如果主容器my-mysql中已經(jīng)存在用戶數(shù)據(jù), 那么在進(jìn)行主從復(fù)制時, 需要做如下處理:
1. 主數(shù)據(jù)庫鎖表操作, 不讓數(shù)據(jù)再進(jìn)行寫入操作.
[root@localhost mysql_bk]# docker exec -it my-mysql bash
root@615c9b2e4fa3:/# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.6.37-log MySQL Community Server (GPL)
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
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> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.01 sec)
2. 查看主數(shù)據(jù)庫的狀態(tài)
mysql> show master status;
記下File和Position的值, 以備從服務(wù)器使用.
3. 把主服務(wù)器的數(shù)據(jù)文件復(fù)制到從服務(wù)器.
(1). 將主數(shù)據(jù)庫的數(shù)據(jù)備份到db_dev.sql文件
mysqldump -uroot -p db_dev > db_dev.sql
(2). 將備份的數(shù)據(jù)文件復(fù)制宿主機(jī)器中.
docker cp my-mysql:/usr/local/mysql/mysql.bak.sql /usr/local/
(3). 將宿主機(jī)器中的備份文件復(fù)制到從數(shù)據(jù)庫容器中
docker cp data/mysql.bak.sql mysql-bk:/usr/local/
(4). 將數(shù)據(jù)復(fù)制到從數(shù)據(jù)庫容器中.
docker cp data/mysql.bak.sql mysql-bk:/usr/local/
(5). 導(dǎo)入數(shù)據(jù)到從容器的數(shù)據(jù)庫中.
mysql -u root -p db_dev < db_dev.sql
4. 取消主數(shù)據(jù)庫鎖定.
mysql> UNLOCK TABLES;
從服務(wù)器的操作和前面的步驟一樣(略過).
驗(yàn)證
在主數(shù)據(jù)庫容器內(nèi)創(chuàng)建新的數(shù)據(jù)庫和表, 然后插入記錄, 再登錄到從數(shù)據(jù)為容器的數(shù)據(jù)庫中, 查看是否也建立相一致的庫和表以及記錄.
mysql> create database db_sync;
Query OK, 1 row affected (0.01 sec)
mysql> create table demo(id int(3), name char(10));
Query OK, 0 rows affected (0.12 sec)
mysql> insert into demo values (001, 'jameszhang');
Query OK, 1 row affected (0.00 sec)
然后, 進(jìn)入到從容器中查看是否存在db_sync數(shù)據(jù)庫, demo表和一筆記錄.
寫得比較倉促, 如有錯誤, 請各位看官幫忙批評指正!
