前面我们说了mysql的安装配置(并提供一键安装脚本),mysql语句使用以及备份恢复mysql数据;本次要介绍的是mysql的主从复制,读写分离;及高可用MHA。
 环境如下:
 master:CentOS7_x64 mysql5.721 172.16.3.175 db1
 slave1:CentOS7_x64 mysql5.7.21 172.16.3.235 db2
 slave2:CentOS7_x64 mysql5.7.21 172.16.3.235 db3
 proxysql/MHA:CentOS7_x64 mysql5.7.21 172.16.3.235 proxysql

架构图:
说明:
 配置测试时为了方便关闭了防火墙头,selinux安全策略;
 现实中请开放防火墙策略;myslqdb的安装已经有脚本一键安装并配置好;这里就不在重复配置;只对对应的角色贴出对应的配置或安装与之相关的软件;
一台主数据库,N从节点;从节点开启两个线程,通过Slave_IO_Running线程和主节点上有权限的账号从 主数据库节点复制binlog日志到本地,能过Slave_SQL_Running线程在本地执行binlog日志,达到主从节点内容同步;
master配置:
 egrep -v '(^$|^#)' /usr/local/mysql/etc/my.cnf
- [mysqld]
 - datadir=/data1/mysqldb
 - socket=/tmp/mysql.sock
 - key_buffer_size = 16M
 - max_allowed_packet = 16M
 - thread_stack = 192K
 - thread_cache_size = 8
 - query_cache_limit = 1M
 - query_cache_size = 64M
 - query_cache_type = 1
 - symbolic-links=0
 - innodb_file_per_table=ON
 - skip_name_resolve=ON
 - server-id = 1
 - log_bin = /data1/mysqldb/mysql-bin.log
 - [mysqld_safe]
 - log-error=/usr/local/mysql/logs/error.log
 - pid-file=/data1/mysqldb/mysql.pid
 - !includedir /usr/local/mysql/etc/my.cnf.d
 
创建从节点同步账号:
- mysql > grant replication client,replication slave on *.* to 'repluser'@'172.16.3.%' identified by 'replpass';
 - mysql > flush privileges;
 - mysql >show master logs;
 - +------------------+-----------+
 - | Log_name | File_size |
 - +------------------+-----------+
 - | mysql-bin.000001 | 622 |
 
 主节点上的binlog日志文件及位置;请记下;从节点第一次同步时需要用;
slave节点:
 egrep -v '(^$|^#)' /usr/local/mysql/etc/my.cnf 
- [mysqld]
 - datadir=/data1/mysqldb
 - socket=/data1/mysqldb/mysql.sock
 - key_buffer_size = 16M
 - max_allowed_packet = 16M
 - thread_stack = 192K
 - thread_cache_size = 8
 - query_cache_limit = 1M
 - query_cache_size = 64M
 - query_cache_type = 1
 - symbolic-links=0
 - innodb_file_per_table=ON
 - skip_name_resolve=ON
 - server-id = 11 #从节点标识ID 各从节点均不一样
 - relay_log = relay-log
 - read_only=ON
 - [mysqld_safe]
 - log-error=/usr/local/mysql/log/error.log
 - pid-file=/var/run/mysql/mysql.pid
 - !includedir /usr/local/mysql/etc/my.cnf.d
 
启动mysq数据库
 注意:两台从节点的server-id 值不一样;其他的都一样;因此从节点只展示一个配置文件;
登录数据库并同步数据启动slave
 两台slave均要同步并启动 
- mysql > CHANGE MASTER TO MASTER_HOST="172.16.3.175",MASTER_USER="repluser",MASTER_PASSWORD="replpass",MASTER_PORT=3306,MASTER_LOG_FILE="mysql-bin.000001",MASTER_LOG_POS=622;
 - mysql > start slave; #启动从节点()
 - #查看从节点状态
 - mysql > SHOW SLAVE STATUS;
 - *************************** 1. row ***************************
 - Slave_IO_State: Waiting for master to send event
 - Master_Host: 172.16.3.175 #主节点
 - Master_User: repluser #同步账号
 - Master_Port: 3306
 - Connect_Retry: 60
 - Master_Log_File: mysql-bin.000001
 - Read_Master_Log_Pos: 622
 - Relay_Log_File: relay-log.000001
 - Relay_Log_Pos: 582
 - Relay_Master_Log_File: mysql-bin.000001
 - Slave_IO_Running: Yes #同步线程正常
 - Slave_SQL_Running: Yes #本地写线程正常
 - Replicate_Do_DB: #同步过滤为空(可以只同步某个或某些库)
 - Replicate_Ignore_DB: #不同步的库
 - Replicate_Do_Table:
 - Replicate_Ignore_Table:
 - Replicate_Wild_Do_Table:
 - Replicate_Wild_Ignore_Table:
 - Last_Errno: 0 #最后同步的错误 0表示正常同步
 - Last_Error:
 - Skip_Counter: 0
 - Exec_Master_Log_Pos: 622
 - Relay_Log_Space: 615
 - 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: 57017c43-36e3-11e8-ac76-080027393fc7
 - Master_Info_File: /data1/mysqldb/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)
 - ERROR:
 - No query specified
 
测试主从同步
 在master导入测试数据;修改数据并查看slave 中的数据是否一致; 
- [root@db1 ~]# mysql < Testdb.sql
 - 登录数据库
 - [root@db1 ~]# mysql -uroot -p
 - mysql> show databases;
 - +--------------------+
 - | Database |
 - +--------------------+
 - study |
 - +--------------------+
 - 5 rows in set (0.00 sec)
 - ###study测试数据库导入成功
 - mysql> use study;
 - Database changed
 - mysql> show tables;
 - +-----------------+
 - | Tables_in_study |
 - +-----------------+
 - | class |
 - | course |
 - | part |
 - | score |
 - | student |
 - | tb31 |
 - | tb32 |
 - | teacher |
 - | test1 |
 - | test2 |
 - | user_info |
 - +-----------------+
 - 11 rows in set (0.00 sec)
 - #删除test1 test2表
 
slave从节点上查看 
- mysql> show tables;
 - +-----------------+
 - | Tables_in_study |
 - +-----------------+
 - | class |
 - | course |
 - | part |
 - | score |
 - | student |
 - | tb31 |
 - | tb32 |
 - | teacher |
 - | user_info |
 - +-----------------+
 - 9 rows in set (0.00 sec)
 
数据已经可以正常同步;注意主从同步只需要第一次手动启动;之后都随mysql服务自动启动;主从同步架构只方便了数据的同步,此时如果没有 第三方工具介入想做到读写分离就需要在程序中去做,难免出错;而出错了,就需要手动同步数据;这里通过proxysql来做读写分离;
以上已经完成了主从复制配置;然而这只是一个基本配置,加上一个proxysql实现mysql读写分离,proxysql类似haproxy七层代理路由功能且支持MySQL 协议的的数据库代理;是dba开发给dba使用的;用户请求发向proxysql,如果是写请求发往主节点;读请求发下从节点组中;以此实现读写分离;一定程序上减轻了主数据库的io压力;
 下载安装proxysql
 目前最新版本是1.4.7-1(由于最新版本有问题)
 我们这里下载使用1.3.6-1的基于CentOS7的rpm包;下载到本地并yum安装 
- [root@proxysql ~]# yum install proxysql-1.3.6-1-centos7.x86_64.rpm -y
 - [root@proxysql ~]# rpm -ql proxysql
 - /etc/init.d/proxysql
 - /etc/proxysql.cnf #主配置文件
 - /usr/bin/proxysql
 - /usr/share/proxysql/tools/proxysql_galera_checker.sh
 - /usr/share/proxysql/tools/proxysql_galera_writer.pl
 
配置如下:
 在配置proxysql之前需要在主节点配置授权账号以作proxysql对主从节点操作;另外proxysql上的mysql客户端工具需要和主从节点上的保持一致;
在主节点master上授权登录账号:
- mysql > GRANT ALL ON *.* TO 'myadmin'@'172.16.3.%' identified by 'mypass';
 
proxysql.cnf配置
- [root@proxysql ~]# egrep -v '(^$|^#)' /etc/proxysql.cnf
 
- datadir="/var/lib/proxysql"
 - admin_variables=
 - {
 - admin_credentials="admin:admin" #proxysql自己的管理用户名密码
 - mysql_ifaces="127.0.0.1:6032;/tmp/proxysql_admin.sock"
 - }
 - mysql_variables=
 - {
 - threads=4 #线程数,建议和cpu核心数一致
 - max_connections=2048 #最大连接
 - default_query_delay=0
 - default_query_timeout=36000000
 - have_compress=true
 - poll_timeout=2000
 - interfaces="0.0.0.0:3306;/tmp/proxysql.sock" #对外接口
 - default_schema="information_schema"
 - stacksize=1048576
 - server_version="5.5.30"
 - connect_timeout_server=3000
 - monitor_username="monitor"
 - monitor_password="monitor"
 - monitor_history=600000
 - monitor_connect_interval=60000
 - monitor_ping_interval=10000
 - monitor_read_only_interval=1500
 - monitor_read_only_timeout=500
 - ping_interval_server_msec=120000
 - ping_timeout_server=500
 - commands_stats=true
 - sessions_sort=true
 - connect_retries_on_failure=10
 - }
 - #####主从节点的配置
 - mysql_servers =
 - (
 - {
 - address = "172.16.3.175" # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - port = 3306 # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - hostgroup = 1 # 设置组号
 - status = "ONLINE" # default: ONLINE
 - weight = 1 # default: 1
 - compression = 0 # default: 0
 - max_connections = 200 ###定义最大的连接
 - },
 - {
 - address = "172.16.3.235" # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - port = 3306 # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - hostgroup = 2 # no default, required
 - status = "ONLINE" # default: ONLINE
 - weight = 1 # default: 1
 - compression = 0 # default: 0
 - max_connections=1000
 - },
 - {
 - address = "172.16.3.241" # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - port = 3306 # no default, required . If port is 0 , address is interpred as a Unix Socket Domain
 - hostgroup = 2 # no default, required
 - status = "ONLINE" # default: ONLINE
 - weight = 1 # default: 1
 - compression = 0 # default: 0
 - max_connections=1000
 - }
 - )
 - mysql_users:
 - (
 - {
 - username = "myadmin" # no default , required
 - password = "mypass" # default: ''
 - default_hostgroup = 1 # default: 0
 - max_connections=1000
 - default_schema="test"
 - active = 1 #是否激活
 - }
 - )
 - mysql_query_rules:
 - (
 - )
 - scheduler=
 - (
 - )
 - mysql_replication_hostgroups=
 - (
 - {
 - writer_hostgroup=1 #定义写组号1
 - reader_hostgroup=2 #定义读组号2
 - comment="test repl 1" #注释内容
 - }
 - )
 
启动proxysql服务
- [root@proxysql ~]# service proxysql start
 
测试proxysql
模拟通过proxysql使用数据库
 
- [root@proxysql ]# mysql -h172.16.3.175 -umyadmin -pmypass
 - 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 17406
 - Server version: 5.7.21-log MySQL Community Server (GPL)
 - Copyright (c) 2000, 2018, 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>
 - mysql > show databases;
 - mysql> show databases;
 - +--------------------+
 - | Database |
 - +--------------------+
 - | information_schema |
 - | mysql |
 - | performance_schema |
 - | study |
 - | sys |
 - +--------------------+
 - 5 rows in set (0.00 sec)
 - ###删除study数据库user_info中6 -12之间的数据
 
 删除之前:
 
- mysql> select * from user_info;
 - +-----+-------+------+--------+----------+
 - | nid | name | age | gender | part_nid |
 - +-----+-------+------+--------+----------+
 - | 1 | san | 20 | 男 | 1 |
 - | 2 | dong | 29 | 男 | 2 |
 - | 4 | Ling | 28 | 男 | 4 |
 - | 5 | ling | 28 | 男 | 3 |
 - | 6 | dong | 30 | 男 | 1 |
 - | 7 | b | 11 | 女 | 1 |
 - | 8 | c | 12 | 女 | 1 |
 - | 9 | d | 18 | 女 | 4 |
 - | 10 | e | 22 | 男 | 3 |
 - | 11 | f | 23 | 男 | 2 |
 - | 12 | dongy | 22 | 男 | 1 |
 - +-----+-------+------+--------+----------+
 - 11 rows in set (0.00 sec)
 
 删除之后:
 
mysql> delete from user_info where nid >6 and nid <12;
Query OK, 5 rows affected (0.03 sec)
mysql> select * from user_info;
+-----+-------+------+--------+----------+
| nid | name | age | gender | part_nid |
+-----+-------+------+--------+----------+
| 1 | san | 20 | 男 | 1 |
| 2 | dong | 29 | 男 | 2 |
| 4 | Ling | 28 | 男 | 4 |
| 5 | ling | 28 | 男 | 3 |
| 6 | dong | 30 | 男 | 1 |
| 12 | dongy | 22 | 男 | 1 |
+-----+-------+------+--------+----------+
6 rows in set (0.00 sec)
到主从节点上查看,会发现以上的查和修改数据都被proxysql正确的代理到后端处理了;
 以上看了并不直观;为了查看proxysql与各主从节点通讯我们在主从节点上安装tcpdump并过滤包
主节点:
 类似如下:
 
- [root@db1 ~]# tcpdump -i enp0s3 -nn tcp port 3306
 - tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
 - listening on enp0s3, link-type EN10MB (Ethernet), capture size 262144 bytes
 - 18:04:34.678861 IP 172.16.3.254.42191 > 172.16.3.175.3306: Flags [S], seq 3385407732, win 29200, options [mss 1460,sackOK,TS val 17576713 ecr 0,nop,wscale 7], length 0
 - 18:04:34.678908 IP 172.16.3.175.3306 > 172.16.3.254.42191: Flags [S.], seq 1579426335, ack 3385407733, win 28960, options [mss 1460,sackOK,TS val 29413673 ecr 17576713,nop,wscale 7], length 0
 - 18:04:34.680902 IP 172.16.3.254.42191 > 172.16.3.175.3306: Flags [.], ack 1, win 229, options [nop,nop,TS val 17576715 ecr 29413673], length 0
 - 18:04:34.681264 IP 172.16.3.175.3306 > 172.16.3.254.42191: Flags [P.], seq 1:83, ack 1, win 227, options [nop,nop,TS val 29413675 ecr 17576715], length 82
 - ....
 
 从节点:
 类似如下:
 
[root@db2 data1]# tcpdump -i enp0s3 -nn tcp port 3306
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp0s3, link-type EN10MB (Ethernet), capture size 262144 bytes
18:02:57.932043 IP 172.16.3.254.42733 > 172.16.3.235.3306: Flags [S], seq 76520456, win 29200, options [mss 1460,sackOK,TS val 17479189 ecr 0,nop,wscale 7], length 0
...........
proxysql命令行管理接口:支持运行时修改 
- [root@proxysql]# mysql -u admin -padmin -h 127.0.0.1 -P6032 --prompt='Admin> '
 - Admin> show databases;
 - +-----+---------+-------------------------------+
 - | seq | name | file |
 - +-----+---------+-------------------------------+
 - | 0 | main | |
 - | 2 | disk | /var/lib/proxysql/proxysql.db |
 - | 3 | stats | |
 - | 4 | monitor | |
 - +-----+---------+-------------------------------+
 - 4 rows in set (0.00 sec)
 
以上stats,monitor,main都从配置文件中获取的数据库;可以通过类似mysql运行时修改;而不需要重启;更多命令行的配置请参考github;
至此我们基于proxysql主从复制读写分离架构已经完成;
 双主或多主模型是无须实现读写分离,仅需要负载均衡:haproxy, nginx, lvs等;
proxysql并没有解决,当主数据岩机时的问题;此时就需要量MHA来解决 ;后续再介绍;
                本文名称:MySQL主从复制读写分离与高可用配置
                
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