keepalived实现nginx的高可用

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keepalived实现nginx HA的做法，搭建好nginx反向代理tomcat并利用自身模块proxy_cache实现web缓存的架构，该博文中的nginx安装在hadoop1节点上，按照博文中的nginx的安装配置，配置好hadoop0，这样就有两个节点安装了nginx并实现了web缓存和反向代理。这里hadoop0作为nginx的master，而hadoop1作为nginx的backup，以此来配置keepalived。    在hadoop0、hadoop1上安装keepalived

1	yum install keepalived -y

    hadoop0上keepalived的配置如下

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[iyunv@hadoop0 ~]# 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    smtp_server 127.0.0.1    smtp_connect_timeout 30    router_id LVS_DEVEL } vrrp_script check_nginx {     script "/opt/check_nginx.sh"     interval 2 } vrrp_instance VI_2 {     state MASTER     interface eth0     virtual_router_id 52     priority 100     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {         192.168.0.207     }     track_script {         check_nginx     } }

    hadoop1上keepalived的配置如下

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[iyunv@hadoop1 ~]# 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    smtp_server 127.0.0.1    smtp_connect_timeout 30    router_id LVS_DEVEL } vrrp_instance VI_2 {     state BACKUP     interface eth0     virtual_router_id 52     priority 80     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {         192.168.0.207     } }

    从上面的配置看到，keepalived代理nginx实现HA之后的虚拟IP为192.168.0.207，监控nginx的脚本内容如下

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[iyunv@hadoop0 ~]# cat  /opt/check_nginx.sh #!/bin/bash #author: kora #date: 2014-10-21 #description: check service such as nginx # #set -x CHECK_TIME=3 NGINX_OK=1 NOW=`date` STATUS='OK!' procnum=`ps -ef |grep "/usr/local/nginx/sbin/nginx"|grep -v "grep"|wc -l` while [ "$CHECK_TIME" -ne 0 ] do     let "CHECK_TIME-=1"     if [ "$procnum" -eq 1 -a -f /usr/local/nginx/logs/nginx.pid ]     then         NGINX_OK=1         CHECK_TIME=0     else         NGINX_OK=0     fi done if [ "$NGINX_OK" -eq 0 ] then     status='fail!'     /etc/init.d/keepalived stop fi echo "$NOW:$STATUS" >> /usr/local/nginx/logs/keepalived.log exit 0

    当master上的nginx挂掉之后，脚本会停调keepalived服务，从而将虚拟IP浮动到hadoop1上，实现高可用，而用户需要使用虚拟IP192.168.0.207来访问web应用。