Centos 7 配置keepalived

1、安装keepalived并将其配置成系统服务。

环境介绍:两台centos7虚拟机
master1:192.168.23.129
master2:192.168.23.130
vip(虚拟Ip):192.168.23.188

master1和master2两台机器上同样进行如下操作：

# 下载与安装
yum install -y openssl-devel popt-devel
cd /usr/local/src/
wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz
tar -zvxf keepalived-1.3.5.tar.gz
cd keepalived-1.3.5
./configure --prefix=/usr/local/keepalived
make && make install
  
cp /usr/local/src/keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
echo "/etc/init.d/keepalived start" >> /etc/rc.local
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak

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）

1.主机master上配置

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 {
router_id MASTER-HA
}
       
vrrp_script chk_mysql_port {
    script "/etc/keepalived/chk_mysql.sh"
    interval 2            
    weight 2                 
    fall 2                 
    rise 1               
}
       
vrrp_instance VI_1 {
    state MASTER
    interface ens33    
    mcast_src_ip 192.168.1.146
    virtual_router_id 51    
    priority 101          
    advert_int 1         
    authentication {   
        auth_type PASS 
        auth_pass 1111     
    }
    virtual_ipaddress {    
        192.168.1.188
    }
      
track_script {               
   chk_mysql_port             
}
}
virtual_server 192.168.23.188 3306 {
    delay_loop 6               
    lb_algo rr             
    lb_kind NAT                 
    #nat_mask 255.255.255.0
    persistence_timeout 50     
    protocol TCP              
    
    ## Real Server设置，3306就是连接端口
    real_server 192.168.23.129 3306 {
        weight 3  #权重
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 3306
        }
    }
    real_server 192.168.23.130 3306 {
        weight 3
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 3306
        }
    }
}

2.主机master2上的配置

! Configuration File for keepalived
       
global_defs {
router_id BACKUP-HA
}
       
vrrp_script chk_mysql_port {
    script "/etc/keepalived/chk_mysql.sh"
    interval 2            
    weight 2                 
    fall 2                 
    rise 1               
}
       
vrrp_instance VI_1 {
    state BACKUP
    interface ens33    
    mcast_src_ip 192.168.23.130
    virtual_router_id 51    
    priority 99          
    advert_int 1         
    authentication {   
        auth_type PASS 
        auth_pass 1111     
    }
    virtual_ipaddress {    
        192.168.23.188
    }
      
track_script {               
   chk_mysql_port             
}
}
virtual_server 192.168.23.188 3306 {
    delay_loop 6               #服务轮询的时间间隔
    lb_algo rr                #加权轮询调度，LVS调度算法 rr|wrr|lc|wlc|lblc|sh|sh
    lb_kind NAT                 #LVS集群模式 NAT|DR|TUN，其中DR模式要求负载均衡器网卡必须有一块与物理网卡在同一个网段
    #nat_mask 255.255.255.0
    persistence_timeout 50     #会话保持时间
    protocol TCP              #健康检查协议
    
    ## Real Server设置，3306就是连接端口
    real_server 192.168.23.129 3306 {
        weight 3  ##权重
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 3306
        }
    }
    real_server 192.168.23.130 3306 {
        weight 3
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 3306
        }
    }
}

3.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。

# 编辑脚本
vim /etc/keepalived/chk_mysql.sh

编写具体脚本

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

4.启动keepalived

# 给脚本赋权
chmod 755 /etc/keepalived/chk_mysql.sh

# 启动keepalived服务
/etc/init.d/keepalived start

#可以看到 vip在master上
ip addr

问题解决

问题描述:由防火墙导致的脑裂问题

注意:应该永久关闭防火墙,cent os7以前是iptables,之后是firewall

Keepalived是一个轻量级的HA集群解决方案，但开启防火墙后各节点无法感知其它节点的状态，各自都绑定了虚拟IP。网上很多文章讲要配置防火墙放过tcp/112，在CentOS7下是无效的，正确的做法是配置放过vrrp协议，方法如下：

firewall-cmd --direct --permanent --add-rule ipv4 filter INPUT 0 --destination 224.0.0.18 --protocol vrrp -j ACCEPT
firewall-cmd --direct --permanent --add-rule ipv4 filter OUTPUT 0 --destination 224.0.0.18 --protocol vrrp -j ACCEPT

firewall-cmd --reload

Keepalived使用vrrp组播，默认地址是224.0.0.18，因此要配置防火墙放过。完成后再用ip addr查看，集群已经正常了，只有主节点绑定虚拟IP，备份节点不会绑定了。

启动的时候有可能启动失败

在启动的时候有可能启动失败 ,修改PIDFile的位置

vim /lib/systemd/system/keepalived.service
# 在第7行修改,发现这个目录不存在，无法写入
PIDFile=/usr/local/program/keepalived/var/run/keepalived.pid   
#修改成 
PIDFile=/var/run/keepalived.pid 
#重新载入 systemd，扫描新的或有变动的单元 
systemctl daemon-reload

在运行就Ok了

etc/init.d/keepalived start

原文链接：https://blog.csdn.net/qq_41695041/article/details/113338105