nginx-keepalive-高可用

最新推荐文章于 2025-05-11 18:11:40 发布

翻译最新推荐文章于 2025-05-11 18:11:40 发布 · 417 阅读

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#高可用 #nginx #keepalive #抢占模式 #非抢占模式

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keepalive的HA分为抢占模式和非抢占模式

抢占模式指：在master挂机恢复后会把VIP从backup节点中抢占过来，再次升级为master。

非抢占模式指：在master挂机恢复后不会抢占backup再次升级master。

配置

基本环境：nginx01Master:192.168.80.137
          nginx02Backup:192.168.80.132
          VIP   :192.168.80.100
       关闭iptables,firewall,selinux
基本操作：
       时间校准：update ntp.api.bz

抢占模式配置

	#####master(192.168.80.137)keepalived.conf配置如下>#######
[root@liusq-2 keepalived]# cat 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
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_script chk_nginx {
	script "/etc/keepalived/nginx_check.sh"
	interval 4
	weight -20
	}
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.100
    }
	track_script {
	chk_nginx
	}
}
	#####master(192.168.80.132)keepalived.conf配置如下>#######
[root@liusq-1 keepalived]# cat 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
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_script chk_nginx {
	script "/etc/keepalived/nginx_check.sh"
	interval 4
	weight -20
	}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.80.100
    }
	track_script {
	chk_nginx
	}
}



##################nginx_check.sh#############
[root@liusq-2 keepalived]# cat nginx_check.sh
#!/bin/sh
# check nginx server status
NGINX=/usr/local/nginx/sbin/nginx
PORT=80
netstat -antp|grep nginx 

if [ $? -ne 0 ];then
    $NGINX -s stop
    $NGINX
    sleep 3

netstat -antp|grep nginx 
    [ $? -ne 0 ] && service keepalived stop
fi

非抢占模式

   #####master(192.168.80.10)配置如下>#######
   global_defs {
   router_id nginx_01 #标识本节点的名称，通常为hostname
}

vrrp_script chk_nginx {
       script "/etc/keepalived/nginx_check.sh"
       interval 2
       weight -20
}

vrrp_instance VI_1 {
    state BACKUP
    interface enp0s3
    virtual_router_id 51
    mcast_src_ip 192.168.1.201
    priority 100
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.210
    }

    track_script {
       chk_nginx # nginx存活状态检测脚本
    }
}

   #####backup(192.168.80.20)配置如下>#######

global_defs {
   router_id nginx_02
}

vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh"
    interval 2
    weight -20
}

vrrp_instance VI_1 {
    state BACKUP
    interface enp0s3
    virtual_router_id 51
    mcast_src_ip 192.168.1.202
    priority 90
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.210
    }
    track_script {
       chk_nginx
    }
}

和非抢占模式的配置相比，只改了两个地方：
1> 在vrrp_instance块下两个节点各增加了nopreempt指令，表示不争抢vip
2> 节点的state都为BACKUP
两个keepalived节点都启动后，默认都是BACKUP状态，双方在发送组播信息后，会根据优先级来选举一个MASTER出来。
由于两者都配置了nopreempt，所以MASTER从故障中恢复后，不会抢占vip。这样会避免VIP切换可能造成的服务延迟。