http+mysql结合keepalived做热备

preface

公司要求http+mysql+redis+二次开发的ldap要求做高可用，所以此处写写keepalived在这种
环境下的高可用。keepalived这个软件我就不啰嗦了，众所周知，基于VRRP协议做的高可用，VRRP就是virtual route protocol。把这个协议了解透了，keepalived自然也就明白怎么回事了。

实践

环境如下

ip	角色
172.16.160.189	master
172.16.160.179	backup

两台服务器都安装好了http,mysql,redis,以及ldap，确保两台服务器的http，mysql，redis以及ldap服务正常运行。
接下来重点讲解keepalived的配置文件

master 上配置keepalived

配置文件如下：

[root@localhost script]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   router_id LVS_DEVEL         
}

vrrp_script monitor_server {     # monitor_server是自定义名字
     script "/etc/keepalived/script/check_server.sh"   # 设定的脚本，脚本内容下面会贴出来
     interval 1    #探测间隔，实际也是脚本的执行间隔
     weight 0      # 权重，脚本执行后的返回值会与这个做加减法，然后再把值与下面vrrp_instance的权重值做加减。
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    lvs_sync_daemon_inteface eth0
    virtual_router_id 51    # 与备份机的id值必须一样的。
    priority 100        # 权重值
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.16.160.250
    }
    track_script {
       monitor_server    # 调用脚本模块
    }
}
virtual_server 172.16.160.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout 50
    protocol http    # 因为这里要访问http协议，所以protocol写成http，这样浏览器才能访问，不然写成TCP的话，浏览器没法访问。

#    real_server 172.16.160.179 80 {
#        weight 100
#	HTTP_CHECK {
#        connect_timeout 2      #(10秒无响应超时)
#        nb_get_retry 1
#        delay_before_retry 1
#        connect_port 80
#	}
#        }
#    real_server 172.16.160.189 80 {
#        weight 100
#	HTTP_CHECK {
#        connect_timeout 2       #(10秒无响应超时)
#        nb_get_retry 1
#        delay_before_retry 1
#        connect_port 80
#	}
#        }
    }

backup上的配置

[root@localhost keepalived]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   router_id LVS_DEVEL1   # 本机id
}

vrrp_script monitor_server{
    script "/etc/keepalived/script/check_server.sh"  # 同上
    interval 1
    weight 0
}

vrrp_instance VI_1 {
    state BACKUP    #角色改为ｂａｃｋｕｐ
    interface eth0
    lvs_sync_daemon_inteface eth0
    virtual_router_id 51    
    priority 90    # 权重值调小即可
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.16.160.250
    }
    track_script {
        monitor_server 
    }
}
virtual_server 172.16.160.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout 50
    protocol HTTP

#    real_server 172.16.160.179 80 {
#        weight 100
#	TCP_CHECK {
#        connect_timeout 2      #(10秒无响应超时)
#        nb_get_retry 1
#        delay_before_retry 1
#        connect_port 80
#	}
#        }
#    real_server 172.16.160.189 80 {
#        weight 100
#	TCP_CHECK {
#        connect_timeout 2       #(10秒无响应超时)
#        nb_get_retry 1
#        delay_before_retry 1
#        connect_port 80
#	}
#        }
    }

脚本内容

脚本编写思路很简单，检测每个服务是否在，如果不在，尝试脚本启动，启动不了的话，停止keepalived，这样vip就切换走了。

function judge_ge_1 {
   if [ "$1" -ge "1" ];then
       export result="true"
   else
       export result="false"
   fi
}

function stop_keepalived {
   if [ "$1" == "false" ];then
    service  keepalived stop
   fi
}

################# check redis
exist_port=`netstat -lnpt |grep -v grep | grep 6379 |wc -l`
judge_ge_1 $exist_port
if [ "$result" == "false" ];then
    /etc/init.d/redis start
fi
exist_port=`netstat -lnpt |grep -v grep | grep 6379 |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result

###################### check mysql
exist_port=`netstat -lnpt |grep -v greo | grep 3306 |wc -l`
judge_ge_1 $exist_port
if [ "$result" == "false" ];then
    service mysqld restart
fi
exist_port=`netstat -lnpt |grep -v greo | grep 3306 |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result


################### check http
exist_port=`netstat -lnpt |grep -v grep | grep httpd |wc -l`
judge_ge_1 $exist_port 
if [ "$result" == "false" ];then
    service httpd restart
fi
exist_port=`netstat -lnpt |grep -v grep | grep httpd |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result


[root@localhost script]# chmod 777 /etc/keepalived/script/check_server.sh   # 最后不要忘记添加777的权限，保证具有可执行权限

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