Keepalived+Nginx实现高可用和双主节点负载均衡

简介

Nginx可以实现高并发反向代理，lvs集群可以实现负载均衡，但是他们都有一个共同的弊端，就是Nginx，lvs架构中Director是单点故障，有没有一个好的方案解决这个问题呢？答案是有。通过Keepalived就可以实现，前端Nginx，lvs中Director服务器的高可用和负载均衡，通过shell命令或者脚本可以实现对服务器状态和服务的监控！

一、环境介绍
1、系统环境及软件版本
操作系统：CentOS6.4-i386
软件版本：Nginx-1.4.2
keepalived-1.2.7
yum源：
# vim /etc/yum.repos.d/centos6.repo
[base]
name=centos-base
baseurl=http://mirrors.sohu.com/centos/$releasever/os/$basearch
gpgcheck=1
enable=1
gpgkey=http://mirrors.sohu.com/centos/RPM-GPG-KEY-CentOS-6
[epel]
name=Fedora-epel
baseurl=http://mirrors.sohu.com/fedora-epel/$releasever/$basearch/
enable=1
gpgcheck=0

提示：如果你的系统是centos，系统默认的yum源是可以用的
2、拓扑图

3、IP地址规划
Client: 172.16.254.28
Keepalived+Nginx1: 172.16.3.3 Vip: 172.16.3.100
Keepalived+Nginx2: 172.16.3.4 Vip: 172.16.3.200

二、安装
1、安装keepalived
[root@node1 ~]# yum install keepalived

2、编译安装Nginx

[root@node1 ~]#useradd -r nginx
[root@node1 ~]#yum -y groupinstall "Development tools" "Server Platform Development"
[root@node1 ~]#yum -y install pcre-devel
[root@node1 ~]#tar xf nginx-1.4.2.tar.gz
[root@node1 ~]#cd nginx-1.4.2
[root@node1 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

提示：在两台服务器上都要安装Nginx
3、提供Nginx服务启动脚本

[root@node1 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$nginx)
NGINX_CONF_FILE="/etc/nginx/nginx.conf"
[ -f /etc/sysconfig/nginx] && . /etc/sysconfig/nginx
lockfile=/var/lock/subsys/nginx
make_dirs() {
# make required directories
user=`nginx -V 2>&1 | grep"configure arguments:"| sed's/[^*]*--user=$[^ ]*$.*/\1/g'-`
options=`$nginx -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@node1 nginx-1.4.2]# chmod +x /etc/rc.d/init.d/nginx
[root@node1 nginx-1.4.2]# chkconfig --add nginx
[root@node1 nginx-1.4.2]# chkconfig nginx on
[root@node1 nginx-1.4.2]# service nginx start
Starting nginx: [ OK ]