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centos7下mysql双主+keepalived

一、keepalived简介

keepalived是vrrp协议的实现，原生设计目的是为了高可用ipvs服务，keepalived能够配置文件中的定义生成ipvs规则，并能够对各RS的健康状态进行检测；通过共用的虚拟IP地址对外提供服务；每个热备组内同一时刻只有一台主服务器提供服务，其他服务器处于冗余状态，若当前在线的服务器宕机，其虚拟IP地址将会被其他服务器接替（优先级决定接替顺序），实现高可用为后端主机提供服务。

二、keepalived组件

Keepalived组件介绍

core:keepalived核心组件，主进程的启动和维护，全局配置等。

vrrp stack:keepalived是基于vrrp协议实现高可用vps服务，vrrp则为相关子进程为其提供服务

check:检测keepalived的健康状态相关进程

system call:系统调用

watch dog:监控check和vrrp进程的看管者，check负责检测器子进程的健康状态，当其检测到master上的服务不可用时则通告vrrp将其转移至backup服务器上。

三环境准备

操作系统：centos7.1.1511（core）

数据库： mysql5.7.21 社区版

master1 ：10.0.0.11　　安装mysql 和keeplived

master2 ：10.0.0.12 安装mysql 和keeplived

VIP：10.0.0.20

要实现互为主从，就必须 mster1-->master2设置主从同步同时 master2--->master1 也设置主从同步

四、Mysql主主同步环境部署

---------------master1服务器操作记录---------------
在my.cnf文件的[mysqld]配置区域添加下面内容：
[root@master1 ~]# vim /usr/local/mysql/my.cnf
server-id = 1         
log-bin = mysql-bin     
sync_binlog = 1
binlog_checksum = none
binlog_format = mixed
auto-increment-increment = 2     
auto-increment-offset = 1    
slave-skip-errors = all      
  
[root@master1 ~]# /etc/init.d/mysql restart
Shutting down MySQL. SUCCESS!
Starting MySQL.. SUCCESS!

创建一个复制用户

出了小问题，由于之前root用户的密码设置过于简单在创建复制用户时报如下错误

mysql> grant replication slave,replication client on *.* to repl@'10.0.0.%' identified by '1qaz@WSX';
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

按照提示将密码设置的复杂一点在授权创建就没有问题了

mysql> alter user 'root'@'localhost' identified by '1qaz@WSX';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave,replication client on *.* to repl@'10.0.0.%' identified by '1qaz@WSX';  
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

锁表，待同步配置完成在解锁

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)

查看当前的binlog以及数据所在位置

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000006 |      996 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

---------------master2服务器操作记录---------------
在my.cnf文件的[mysqld]配置区域添加下面内容：
[root@master2 ~]# vim /usr/local/mysql/my.cnf
server-id = 2        
log-bin = mysql-bin    
sync_binlog = 1
binlog_checksum = none
binlog_format = mixed
auto-increment-increment = 2     
auto-increment-offset = 2    
slave-skip-errors = all
  
[root@master2 ~]# /etc/init.d/mysql restart
Shutting down MySQL.. SUCCESS!
Starting MySQL.. SUCCESS!

mysql> grant replication slave,replication client on *.* to repl@'10.0.0.%' identified by '1qaz@WSX';  
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)

查看 master情况

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 |      150 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

分别开启同步对方

---------------master1服务器做同步操作---------------
mysql> unlock tables;     //先解锁，将对方数据同步到自己的数据库中
mysql> slave stop；
mysql> change  master to master_host='10.0.0.12',master_user='repl',master_password='1qaz@WSX',master_log_file='mysql-bin.000001',master_log_pos=150;         
Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

查看两个线程状态是否为YES

mysql> show slave status G;

Slave_IO_Running: Yes
Slave_SQL_Running: Yes

-------------master2服务器做同步操作---------------
mysql> unlock tables;     //先解锁，将对方数据同步到自己的数据库中
mysql> slave stop；
mysql> change  master to master_host='10.0.0.11',master_user='repl',master_password='1qaz@WSX',master_log_file='mysql-bin.000006',master_log_pos=996;  
Query OK, 0 rows affected, 2 warnings (0.06 sec)
  
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
  
mysql> show slave status G;

Master_Log_File: mysql-bin.000006
Read_Master_Log_Pos: 996
Relay_Log_File: master2-relay-bin.000002
Relay_Log_Pos: 312
Relay_Master_Log_File: mysql-bin.000006
Slave_IO_Running: Yes
Slave_SQL_Running: Yes

以上表明双方已经实现了mysql主主同步。

当运行一段时间后，要是发现同步有问题，比如只能单向同步，双向同步失效。可以重新执行下上面的change master同步操作，只不过这样同步后，只能同步在此之后的更新数据。下面开始进行数据验证：

-----------------主主同步效果验证---------------------
1）在master1数据库上写入新数据
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)
  
mysql> create database huanqiu;
Query OK, 1 row affected (0.01 sec)
  
mysql> use huanqiu;
Database changed

mysql> create table if not exists haha ( id int(10) PRIMARY KEY AUTO_INCREMENT, name varchar(50) NOT NULL);
Query OK, 0 rows affected (0.04 sec)

mysql> insert into haha values(2,'guojing');
Query OK, 1 row affected (0.00 sec)

mysql> insert into haha values(1,"huangrong");
Query OK, 1 row affected (0.00 sec)

mysql> select * from haha;
+----+-----------+
| id | name |
+----+-----------+
| 1 | huangrong |
| 2 | guojing |
+----+-----------+
2 rows in set (0.00 sec)

  
然后在master2数据库上查看，发现数据已经同步过来了!

mysql> select * from huanqiu.haha;
+----+-----------+
| id | name |
+----+-----------+
| 1 | huangrong |
| 2 | guojing |
+----+-----------+
2 rows in set (0.00 sec)

2）在master2数据库上写入新数据
mysql> create database hehe;
Query OK, 1 row affected (0.00 sec)

mysql> insert into huanqiu.haha values(3,"haha"),(4,"haha");
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0

  
然后在master1数据库上查看，发现数据也已经同步过来了!
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hehe               |
| huanqiu            |
| mysql              |
| performance_schema |
| test               |
+--------------------+
6 rows in set (0.00 sec)

mysql> select * from huanqiu.haha;
+----+-----------+
| id | name |
+----+-----------+
| 1 | huangrong |
| 2 | guojing |
| 3 | haha |
| 4 | haha |
+----+-----------+
4 rows in set (0.00 sec)

  
至此，Mysql主主同步环境已经实现。

五配置mysql+keepalived 高可用环境

1）安装keepalived并将其配置成系统服务。master1和master2两台机器上同样进行如下操作：
[root@master1 ~]# yum install -y openssl-devel
[root@master1 ~]# cd /usr/local/src/
[root@master1 src]# wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz
[root@master1 src]# tar -zvxf keepalived-1.3.5.tar.gz
[root@master1 src]# cd keepalived-1.3.5
[root@master1 keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived
[root@master1 keepalived-1.3.5]# make && make install
     
[root@master1 keepalived-1.3.5]# cp /usr/local/src/keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@master1 keepalived-1.3.5]# mkdir /etc/keepalived/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@master1 keepalived-1.3.5]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@master1 keepalived-1.3.5]# echo "/etc/init.d/keepalived start" >> /etc/rc.local

2）master1机器上的keepalived.conf配置。（下面配置中没有使用lvs的负载均衡功能，所以不需要配置虚拟服务器virtual server）

[root@master1 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master1 ~]# vim /etc/keepalived/keepalived.conf       ＃清空默认内容，直接采用下面配置：
! Configuration File for keepalived
       
global_defs {
notification_email {
ops@wangshibo.cn
tech@wangshibo.cn
}
       
notification_email_from ops@wangshibo.cn
smtp_server 127.0.0.1 
smtp_connect_timeout 30
router_id MASTER-HA
}
       
vrrp_script chk_mysql_port {     #检测mysql服务是否在运行。有很多方式，比如进程，用脚本检测等等
    script "/opt/chk_mysql.sh"   #这里通过脚本监测
    interval 2                   #脚本执行间隔，每2s检测一次
    weight -5                    #脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5
    fall 2                    #检测连续2次失败才算确定是真失败。会用weight减少优先级（1-255之间）
    rise 1                    #检测1次成功就算成功。但不修改优先级
}
       
vrrp_instance VI_1 {
    state MASTER    
    interface eth0      #指定虚拟ip的网卡接口
    mcast_src_ip 10.0.0.11
    virtual_router_id 51    #路由器标识，MASTER和BACKUP必须是一致的
    priority 101            #定义优先级，数字越大，优先级越高，在同一个vrrp_instance下，MASTER的优先级必须大于BACKUP的优先级。这样MASTER故障恢复后，就可以将VIP资源再次抢回来 
    advert_int 1         
    authentication {   
        auth_type PASS 
        auth_pass 1111     
    }
    virtual_ipaddress {    
        10.0.0.20
    }
      
track_script {               
   chk_mysql_port             
}
}

编写切换脚本。KeepAlived做心跳检测，如果Master的MySQL服务挂了(3306端口挂了),那么它就会选择自杀。Slave的KeepAlived通过心跳检测发现这个情况，就会将VIP的请求接管

[root@master1 ~]# vim /opt/chk_mysql.sh
#!/bin/bash
counter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)
if [ "${counter}" -eq 0 ]; then
    /etc/init.d/keepalived stop
fi

[root@master1 ~]# chmod 755 /opt/chk_mysql.sh
     
启动keepalived服务
[root@master1 ~]# /etc/init.d/keepalived start
正在启动 keepalived：                                      [确定]

4）master2机器上的keepalived配置。master2机器上的keepalived.conf文件只修改priority为90、nopreempt不设置、real_server设置本地IP。

[root@master2 ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@master2 ~]# >/etc/keepalived/keepalived.conf
[root@master2 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
       
global_defs {
notification_email {
ops@qq.com
tech@qq.com
}
       
notification_email_from ops@wangshibo.cn
smtp_server 127.0.0.1 
smtp_connect_timeout 30
router_id MASTER-HA
}
       
vrrp_script chk_mysql_port {
    script "/opt/chk_mysql.sh"
    interval 2            
    weight -5                 
    fall 2                 
    rise 1               
}
       
vrrp_instance VI_1 {
    state BACKUP
    interface eth0    
    mcast_src_ip 10.0.0.12
    virtual_router_id 51    
    priority 99          
    advert_int 1         
    authentication {   
        auth_type PASS 
        auth_pass 1111     
    }
    virtual_ipaddress {    
        10.0.0.20
    }
      
track_script {               
   chk_mysql_port             
}
}
     
     
[root@master2 ~]# cat /opt/chk_mysql.sh
#!/bin/bash
counter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)
if [ "${counter}" -eq 0 ]; then
    /etc/init.d/keepalived stop
fi
 
[root@master2 ~]# chmod 755 /opt/chk_mysql.sh
     
[root@master2 ~]# /etc/init.d/keepalived start
正在启动 keepalived：                                      [确定]

我这里启动时出现了问题，分析日志

tail -f /var/log/message
Mar 31 14:28:14 master1 systemd: Configuration file /usr/lib/systemd/system/ebtables.service is marked executable. Please remove executable permission bits. Proceeding anyway.

查看keepalived.service

# vi /lib/systemd/system/keepalived.service

[Unit]
Description=LVS and VRRP High Availability Monitor
After=syslog.target network-online.target

[Service]
Type=forking
# PIDFile=/usr/local/keepalived/var/run/keepalived.pid

# 上面这个注释掉改成下面因为这个默认路径不存在所以就无法写入进程ID文件

PIDFile=/var/run/keepalived.pid
KillMode=process
EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

5）master1和master2两台服务器都要授权允许root用户远程登录，用于在客户端登陆测试！

mysql> grant all on *.* to root@'10.0.0.%' identified by "1qaz@WSX";
Query OK, 0 rows affected (0.00 sec)
     
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

6）在master1和master2两台机器上设置iptables防火墙规则，如下：

[root@master1 ~]# cat /etc/sysconfig/iptables
........
-A INPUT -s 10.0.0.0/24 -d 224.0.0.18 -j ACCEPT       #允许组播地址通信
-A INPUT -s 10.0.0.0/24 -p vrrp -j ACCEPT             #允许VRRP（虚拟路由器冗余协）通信
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT    #开放mysql的3306端口
   
[root@master1 ~]# /etc/init.d/iptables restart

六 Mysql＋keepalived故障转移的高可用测试

1）通过Mysql客户端通过VIP连接，看是否连接成功。

比如，在远程一台测试机上连接，通过vip地址可以正常连接（下面的连接权限要是在服务端提前授权的）

[root@master1 ~]# mysql -uroot -p1qaz@WSX -h10.0.0.20
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 11
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> select * from huanqiu.haha;
+----+-----------+
| id | name |
+----+-----------+
| 1 | huangrong |
| 2 | guojing |
| 3 | haha |
| 4 | haha |
+----+-----------+
4 rows in set (0.02 sec)

2）默认情况下，vip是在master1上的。使用"ip addr"命令查看vip切换情况

[root@master1 ~]# ip addr |grep 10.0                 
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 10.0.0.11/8 brd 10.255.255.255 scope global eth0
    inet 10.0.0.20/32 scope global eth0

[root@master2 ~]# ip addr |grep 10.0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
inet 10.0.0.12/8 brd 10.255.255.255 scope global eth0

停止master1机器上的mysql服务，根据配置中的脚本，mysql服务停了，keepalived也会停，从而vip资源将会切换到master2机器上。（mysql服务没有起来的时候，keepalived服务也无法顺利启动！）

[root@master1 ~]# systemctl stop mysqld

[root@master1 ~]# ps -ef|grep mysql
root       4431   2423  0 15:08 pts/0    00:00:00 grep --color=auto mysql
[root@master1 ~]# ps -ef|grep keepalived
root       4433   2423  0 15:08 pts/0    00:00:00 grep --color=auto keepalived

[root@master1 ~]# ip addr |grep 10.0                 
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 10.0.0.11/8 brd 10.255.255.255 scope global eth0

查看master2主机

[root@master2 ~]# ip addr |grep 10.0   
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 10.0.0.12/8 brd 10.255.255.255 scope global eth0
    inet 10.0.0.20/32 scope global eth0

3）再次启动master1的mysql和keepalived服务。（注意：如果restart重启mysql，那么还要启动下keepalived，因为mysql重启，根据脚本会造成keepalived关闭）

注意：一定要先启动mysql服务，然后再启动keepalived服务。如果先启动keepalived服务，按照上面的配置，mysql没有起来，就会自动关闭keepalived。

[root@master1 ~]# systemctl start mysqld
[root@master1 ~]# /etc/init.d/keepalived start
Starting keepalived (via systemctl):                       [  OK  ]

[root@master1 ~]# ip addr |grep 10.0          
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    inet 10.0.0.11/8 brd 10.255.255.255 scope global eth0
    inet 10.0.0.20/32 scope global eth0

[root@master2 ~]# ip addr |grep 10.0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
inet 10.0.0.12/8 brd 10.255.255.255 scope global eth0

此时虚拟ip又回到了 master1 主机上了

以上在vip资源切换过程中，对于客户端连接mysql（使用vip连接）来说几乎是没有任何影响的。

---------------------------------温馨提示（Keepalived的抢占和非抢占模式）---------------------------------------

keepalive是基于vrrp协议在linux主机上以守护进程方式，根据配置文件实现健康检查。

VRRP是一种选择协议，它可以把一个虚拟路由器的责任动态分配到局域网上的VRRP路由器中的一台。

控制虚拟路由器IP地址的VRRP路由器称为主路由器，它负责转发数据包到这些虚拟IP地址。

一旦主路由器不可用，这种选择过程就提供了动态的故障转移机制，这就允许虚拟路由器的IP地址可以作为终端主机的默认第一跳路由器。

keepalive通过组播，单播等方式（自定义），实现keepalive主备推选。工作模式分为抢占和非抢占（通过参数nopreempt来控制）。

1）抢占模式：

主服务正常工作时，虚拟IP会在主上，备不提供服务，当主服务优先级低于备的时候，备会自动抢占虚拟IP，这时，主不提供服务，备提供服务。

也就是说，工作在抢占模式下，不分主备，只管优先级。

如上配置，不管keepalived.conf里的state配置成master还是backup，只看谁的priority优先级高（一般而言，state为MASTER的优先级要高于BACKUP）。

priority优先级高的那一个在故障恢复后，会自动将VIP资源再次抢占回来！！

2）非抢占模式：

这种方式通过参数nopreempt（一般设置在advert_int的那一行下面）来控制。不管priority优先级，只要MASTER机器发生故障，VIP资源就会被切换到BACKUP上。

并且当MASTER机器恢复后，也不会去将VIP资源抢占回来，直至BACKUP机器发生故障时，才能自动切换回来。

千万注意：

nopreempt这个参数只能用于state为backup的情况，所以在配置的时候要把master和backup的state都设置成backup，这样才会实现keepalived的非抢占模式！

也就是说：

a）当state状态一个为master，一个为backup的时候，加不加nopreempt这个参数都是一样的效果。即都是根据priority优先级来决定谁抢占vip资源的，是抢占模式！

b）当state状态都设置成backup，如果不配置nopreempt参数，那么也是看priority优先级决定谁抢占vip资源，即也是抢占模式。

c）当state状态都设置成backup，如果配置nopreempt参数，那么就不会去考虑priority优先级了，是非抢占模式！即只有vip当前所在机器发生故障，另一台机器才能接管vip。即使优先级高的那一台机器恢复后也不会主动抢回vip，只能等到对方发生故障，才会将vip切回来。

---------------------------------mysql状态检测脚本优化---------------------------------

上面的mysql监测脚本有点过于简单且粗暴，即脚本一旦监测到Master的mysql服务关闭，就立刻把keepalived服务关闭，从而实现vip转移！

下面对该脚本进行优化，优化后，当监测到Master的mysql服务关闭后，就会将vip切换到Backup上（但此时Master的keepalived服务不会被暴力kill）
当Master的mysql服务恢复后，就会再次将VIP资源切回来！

[root@master ~]# cat /opt/chk_mysql.sh
#!/bin/bash
MYSQL=/usr/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=1qaz@WSX
CHECK_TIME=3
  
#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
  
MYSQL_OK=1
  
function check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" >/dev/null 2>&1
    if [ $? = 0 ] ;then
    MYSQL_OK=1
    else
    MYSQL_OK=0
    fi
    return $MYSQL_OK
}
while [ $CHECK_TIME -ne 0 ]
do
    let "CHECK_TIME -= 1"
    check_mysql_helth
if [ $MYSQL_OK = 1 ] ; then
    CHECK_TIME=0
    exit 0
fi
if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 0 ]
then
    pkill keepalived
    exit 1
fi
sleep 1
done

来源：https://www.cnblogs.com/benjamin77/p/8682360.html#auto_id_0

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原文地址：https://www.cnblogs.com/chenjw-note/p/12145815.html