keepalived+nginx realizes the high availability of nginx

keepalived+nginx realizes the high availability of nginx

================================ ===

nginx high availability

nginx realizes load balancing of back-end realserver

================== =================

Experimental environment: OS: Centos 6.4( redhat 6.4)yum source:

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[centos]

name=sohu-centos

baseurl=http://mirrors.sohu.com/centos/ $releasever /os/$basearch

gpgcheck=1

enable=0

gpgkey=http://mirrors.sohu.com /centos/RPM- GPG-KEY-CentOS-6

[epel]

name=sohu-epel

baseurl=http://mirrors.sohu.com/fedora-epel/$releasever/$basearch/

enable=1

gpgcheck=0

Topology map:

Planning of topology map:

	IPAddress	Software
Master	172.16.22.1(VIP : 172.16.22.100)	keepalived+nginx
Backup	172.16.22.2 (VIP ：172.16.22.100)	keepalived+ nginx
apache1	172.16.22.3	httpd
apache2	172. 16.22.4	httpd

Issues to consider with this architecture

1), Master is not down, then Master occupies VIP and nginx runs on Master

2), Master is down , the backup seizes the VIP and runs the nginx service on the backup

3). If the nginx service on the master server hangs, the VIP resources are transferred to the backup server

4), detection The health status of the backend server

Both Master and Backup have nginx services enabled. Regardless of Master or Backup, when one of the keepalived services stops, the VIP will drift to the node where the keepalived service is still there,

If you want the nginx service to hang up and the vip to drift to another node, you must use a script or use a shell command in the configuration file to control it.

First of all, it must be clear that keepalived cannot detect the health status of the backend server on this architecture. The health status detection of the backend server is judged by nginx, but the detection mechanism of nginx has certain flaws. , after a certain backend server goes down, nginx will still distribute requests to it. If the backend service cannot respond within a certain period of time, nginx will send it to another server. Then when the customer's request comes, nginx will wait for a while. The request will not be distributed to the down server, but after a period of time, nginx will still send the distribution request to the down server.

1. Install keepalived+nginx

Master:

1. Install keepalived and compile and install ngin x

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[root@jie1 ~]# yum -y install keepalived

[root@jie1 ~]#tar xf nginx-1.4.2.tar.gz

[root@jie1 ~]#yum -y groupinstall "Development tools" "Server Platform Development"

[root@jie1 ~]#yum -y install pcre-devel

[root@jie1 ~]# cd nginx-1.4.2

[root@jie1 nginx-1.4.2]# groupadd nginx

[root@jie1 nginx-1.4.2]# useradd -r -g nginx nginx

[root@jie1 nginx-1.4.2]#./configure

--prefix=/usr

--sbin-path=/usr/sbin/nginx

--conf-path=/etc/nginx/nginx.conf

--error-log-path=/var/log/nginx/error.log

--http-log-path=/var/log/nginx/access.log

--pid-path=/var/run/nginx/nginx.pid 

--lock-path=/var/lock/nginx.lock

--user=nginx

--group=nginx

--with-http_ssl_module

--with-http_flv_module

--with-http_stub_status_module

--with-http_gzip_static_module

--http-client-body-temp-path=/var/tmp/nginx/client/

--http-proxy-temp-path=/var/tmp/nginx/proxy/

--http-fastcgi-temp-path=/var/tmp/nginx/fcgi/

--http-uwsgi-temp-path=/var/tmp/nginx/uwsgi

--http-scgi-temp-path=/var/tmp/nginx/scgi

--with-pcre

[root@jie1 nginx-1.4.2]# make && make install

2. Provide nginx system V service script file

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[root@jie1 nginx-1.4.2]# vim /etc/rc.d/init.d/nginx

#!/bin/sh

#

# nginx - this script starts and stops the nginx daemon

#

# chkconfig: - 85 15

# description: Nginx is an HTTP(S) server, HTTP(S) reverse

# proxy and IMAP/POP3 proxy server

# processname: nginx

# config: /etc/nginx/nginx.conf

# config: /etc/sysconfig/nginx

# pidfile:     /var/run/nginx.pid

# Source function library.

. /etc/rc.d/init.d/functions

# Source networking configuration.

. /etc/sysconfig/network

# Check that networking is up.

[ "$NETWORKING"= "no"] && exit0

nginx="/usr/sbin/nginx"

prog=$(basename$nginx)

NGINX_C/code>"/etc/nginx/nginx.conf"

[ -f /etc/sysconfig/nginx] && . /etc/sysconfig/nginx

lockfile=/var/lock/subsys/nginx

make_dirs() {

# make required directories

user=`nginx -V 2>&1 | grep"configure arguments:"| sed's/[^*]*--user=([^ ]*).*/1/g'-`

opti -V 2>&1 | grep'configure arguments:'`

foropt in$options; do

if[ `echo$opt | grep'.*-temp-path'` ]; then

value=`echo$opt | cut-d "="-f 2`

if[ ! -d "$value"]; then

# echo "creating" $value

mkdir-p $value && chown-R $user $value

fi

fi

done

}

start() {

[ -x $nginx ] || exit5

[ -f $NGINX_CONF_FILE ] || exit6

make_dirs

echo-n $"Starting $prog: "

daemon $nginx -c $NGINX_CONF_FILE

retval=$?

echo

[ $retval -eq0 ] && touch$lockfile

return$retval

}

stop() {

echo-n $"Stopping $prog: "

killproc $prog -QUIT

retval=$?

echo

[ $retval -eq0 ] && rm-f $lockfile

return$retval

}

restart() {

configtest || return$?

stop

sleep1

start

}

reload() {

configtest || return$?

echo-n $"Reloading $prog: "

killproc $nginx -HUP

RETVAL=$?

echo

}

force_reload() {

restart

}

configtest() {

$nginx -t -c $NGINX_CONF_FILE

}

rh_status() {

status $prog

}

rh_status_q() {

rh_status >/dev/null2>&1

}

case"$1"in

start)

rh_status_q && exit0

$1

;;

stop)

rh_status_q || exit0

$1

;;

restart|configtest)

$1

;;

reload)

rh_status_q || exit7

$1

;;

force-reload)

force_reload

;;

status)

rh_status

;;

condrestart|try-restart)

rh_status_q || exit0

;;

*)

echo$"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload|configtest}"

exit2

esac

[root@jie1 nginx-1.4.2]# chmod +x /etc/rc.d/init.d/nginx

[root@jie1 nginx-1.4.2]# service nginx start

Starting nginx:                                                                                                                       nginx-1.4.2]

# scp -p /etc/rc.d/init.d/nginx 172.16.22.2:/etc/rc.d/init.d #Copy the nginx service script to the backup, -p means to maintain the original permissions

3. Modify configuration file

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[root@jie1 ~]

# cd /etc/keepalived/

[root@jie1 keepalived]

# vim keepalived.conf

global_defs {

​​

notification_email {

root@localhost