前面讲到了部署多个tomcat和多个rabbitmq用nginx做代理服务器，这种情况，tomcat和rabbitmq既实现了高可用又实现了负载均衡。但是，nginx确成了单点。在一个HA环境中，任何一个点都必须实现高可用，这里就需要借助keepalived来实现nginx的高可用。
测试环境
host1 192.168.30.1 (nginx, keepalived/master)host2 192.168.30.2 (nginx, keepalived/backup)
安装keepalived
host1和host2分别安装keepalived, host2安装nginx(过程略)
$ yum install keepalived
准备nginx状态检测脚本
/etc/keepalived/check_nginx.sh
#!/bin/bash
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
/usr/local/nginx/sbin/nginx
sleep 5
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
killall keepalived
fi
fi
拷贝到host2
$ scp /etc/keepalived/check_nginx.sh root@192.168.30.2:/etc/keepalived/check_nginx.sh
修改host1的keepalived配置
! Configuration File for keepalived
global_defs {
notification_email {
test@sanlogic.com
}
notification_email_from test@test.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/etc/keepalived/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.30.30
}
}
修改host2的keepalived配置文件
! Configuration File for keepalived
global_defs {
notification_email {
test@sanlogic.com
}
notification_email_from test@test.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/etc/keepalived/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 50
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.30.30
}
}
启动keepalived
$ systemctl enable keepalived
$ systemctl start keepalived
测试
用浏览器访问http://192.168.30.30/hellonginx，出现如下界面
这时关闭host1
$ halt -p
用浏览器访问http://192.168.30.30/hellonginx，仍然是如下界面
Done !
