nginx + keepalived achieve hot standby HA

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This article describes the use of simple keepalived software, to achieve the nginx high availability servers, namely the failure to achieve automatic switching. Assuming you have installed nginx , following the installation and use of keepalived.

keepalived installation

yum install openssl-devel
cd /tmp
wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
tar xzf keepalived-1.2.2.tar.gz
cd keepalived-1.2.2
./configure
make && make install
cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
chmod +x /etc/init.d/keepalived
chkconfig --add keepalived
chkconfig keepalived on
mkdir /etc/keepalived
ln -s /usr/local/sbin/keepalived /usr/sbin/

keepalived configuration

More detailed instructions can be executed keepalived profile man keepalived.conf view.
We assume that the primary server IP: 192.168.1.103, from the server ip: 192.168.1.101 virtual ip: 192.168.1.110
below to keepalived master server to configure:

we /etc/keepalived/keepalived.conf

global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/opt/nginx_pid.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER ############ auxiliary as BACKUP
interface eth0
virtual_router_id 51
mcast_src_ip 192.168.1.103
priority 102 ########### weight higher than back
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
Monitor the implementation of chk_http_port ### service
}
virtual_ipaddress {
192.168.1.110
}
}

From the server:

global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/opt/nginx_pid.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
mcast_src_ip 192.168.1.101
priority 101 ########## weights lower than the master. .
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
Monitor the implementation of chk_http_port ### service
}
virtual_ipaddress {
192.168.1.110
}
}

It was established after the nginx server monitoring scripts from the master:

we /opt/nginx_pid.sh

#!/bin/bash
A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];then
/usr/local/nginx/sbin/nginx
sleep 3
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
be
be

Then start keepalived were the primary server:

service keepalived start

keepalived test

We execute the command ip a server on the primary display as follows:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link / ether 00: 0c: 29: aa: a1: e4 br ff: ff: ff: ff: ff: ff
inet 192.168.1.103/24 brd 255.255.255.255 scope global eth0
inet 192.168.1.110/32 scope global eth0

Prove the primary server is already bound virtual ip 192.168.1.110
in the implementation of the server from the command ip a, shown below:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link / ether 00: 0c: 29: 2b: 94: 3b brd ff: ff: ff: ff: ff: ff
inet 192.168.1.101/24 brd 255.255.255.255 scope global eth0

Display shows that from the server is not bound vip 192.168.1.110, only native real ip192.168.1.101
Let's stop the main server nginx process, look at ip binding information:
when the main server:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link / ether 00: 0c: 29: aa: a1: e4 br ff: ff: ff: ff: ff: ff
inet 192.168.1.103/24 brd 255.255.255.255 scope global eth0

From the server:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link / ether 00: 0c: 29: 2b: 94: 3b brd ff: ff: ff: ff: ff: ff
inet 192.168.1.101/24 brd 255.255.255.255 scope global eth0
inet 192.168.1.110/32 scope global eth0

Thus vip been pointing from the server.