keepalived实现nginx的高可用
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keepalived1
yum install keepalived -y
hadoop0上keepalived的配置如下
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# 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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# 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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# 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。
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