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keepalived+nginx实现nginx的高可用

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Libérer： 2016-08-08 09:22:55

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keepalived+nginx实现nginx的高可用

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nginx的高可用

nginx实现后端realserver的负载均衡

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实验环境：OS：Centos 6.4(redhat 6.4)yum源:

[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

拓扑图：

拓扑图的规划：

	IP地址	软件
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

此架构需考虑的问题

1）、Master没挂，则Master占有vip且nginx运行在Master上

2）、Master挂了，则backup抢占vip且在backup上运行nginx服务

3）、如果master服务器上的nginx服务挂了，则vip资源转移到backup服务器上

4）、检测后端服务器的健康状态

Master和Backup两边都开启nginx服务，无论Master还是Backup，当其中的一个keepalived服务停止后，vip都会漂移到keepalived服务还在的节点上，

如果要想使nginx服务挂了，vip也漂移到另一个节点，则必须用脚本或者在配置文件里面用shell命令来控制。

首先必须明确后端服务器的健康状态检测keepalived在这种架构上是无法检测的，后端服务器的健康状态检测是有nginx来判断的，但是nginx的检测机制有一定的缺陷，后端服务器某一个宕机之后，nginx还是会分发请求给它，在一定的时间内后端服务响应不了，nginx则会发给另外一个服务器，然后当客户的请求来了，nginx会一段时间内不会把请求分发给已经宕机的服务器，但是过一段时间后，nginx还是会把分发请求发给宕机的服务器上。

一、安装keepalived+nginx

Master：

1、安装keepalived和编译安装nginx

[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、提供nginx的system V服务脚本文件

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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

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

;;

stop)

rh_status_q || exit0

;;

restart|configtest)

;;

reload)

rh_status_q || exit7

;;

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: [ OK ]

[root@jie1 nginx-1.4.2]# scp -p /etc/rc.d/init.d/nginx 172.16.22.2:/etc/rc.d/init.d #把nginx的服务脚本复制到backup上，-p是保持原有的权限

3、修改配置文件

[root@jie1 ~]# cd /etc/keepalived/

[root@jie1 keepalived]# vim keepalived.conf

global_defs {

notification_email {

root@localhost