/ 中存储网

CentOS 6系统中部署Nginx+keepalived高可用Web服务器环境

2014-04-13 12:52:01 来源:ITJS.CN
近些年来,Nginx以其自身处理的并发数高,内存消耗小,配置简单,开源免费,支持Rewrite等一系列的有点成为网站Web端的首选软件,同时,Nginx最大的特点是他自身的负载均衡的功能,可以通过定义Upstream地址池,通过相应的分发原则实现网站访问的首选利器,现在的网站最基本的要求就是要稳定高效,这里介绍的Keepalived+Nginx的架构方式就是结合这个来实现的,这里我们采用两台Nginx服务器作为前端,一主一从,Keepalived实现状态监测,保证Nginx正常对外提供服务,即主Nginx服务进程死掉之后,keepalived能够通过其自身的检测机制将网站的访问切换到从Nginx上来。

系统环境:CentOS 5.5

开源软件:nginx-1.2.1.tar.gz  ;    keepalived-1.2.2.tar.gz

主服务器IP:211.151.138.2     从服务IP:211.151.138.3   虚IP:211.151.138.5   你可以将你网站域名解析到 211.151.138.5 这一个公网IP上,这样主从服务器可以轮流接管该虚IP,保证网站正常对外提供访问

keepalived 安装需要依赖 openssl , 直接yum安装即可,yum install openssl openssl-devel

nginx 的安装这里就不介绍了,网上相关文档很多,这里着重介绍 keepalived + nginx 的实现方式

一: 安装 keepalived

主从服务器都操作:

下载 keepalived 软件包

wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz

tar zxvf keepalived-1.2.2 .tar.gz

./configure

make && make install

默认情况下,keepalived 会安装在 /usr/local/keepalived 下,你可以通过 --prefix 定向其安装位置

cp  /usr/local/keepalived/etc/rc.d/init.d/   /etc/init.d/

mkdir  /etc/keepalived  (默认情况下,keepalived 会读取 /etc/keepalived 下keepalived.conf 文件,如果你没有建立这个文件,keepalived也不会报错,但是你会发现,你所创建的关于keepalived的相关参数根本就没有体现,keepalived这一点做的让人挺迷惑的  )

二:此时,我们创建 keepalived.conf 文件

主服务器配置:

vim  /etc/keepalived/keepalived.conf , 键入以下内容

global_defs {

notification_email {

[email protected]     (这里可以定义多个报警邮箱)

}

notification_email_from [email protected] (报警人)

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_http_port {

script "/opt/tools/bin/check_ng.sh"

interval 2                   (检测的间隔)

weight 2

}

vrrp_instance VI_1 {

state MASTER           (显示定义为主服务器)

interface eth1            (绑定的网口,该网口即上面提到的两个IP的接口)

virtual_router_id 51    (定义的ID,官方的是 51,主从服务器必须一直)

mcast_src_ip 211.151.138.2  (主服务器的IP)

priority 100                (优先级,任意定义,但是一定要比从服务器高)    

advert_int 1

authentication {

auth_type PASS      

auth_pass 1111         (默认即可) 

}

track_script {

chk_http_port            (调用检测脚本)

}

virtual_ipaddress {

211.151.137.5         (绑定的虚IP)

}

}

从服务器配置

vim  /etc/keepalived/keepalived.conf , 键入以下内容

global_defs {

notification_email {

[email protected]     (这里可以定义多个报警邮箱)

}

notification_email_from [email protected] (报警人)

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_http_port {

script "/opt/tools/bin/check_ng.sh"

interval 2                           (检测脚本执行的间隔)

weight 2

}

vrrp_instance VI_1 {

state BACKUP           (显示定义为从服务器)

interface eth1            (绑定的网口,该网口即上面提到的两个IP的接口)

virtual_router_id 51    (定义的ID,官方的是 51,主从服务器必须一直)

mcast_src_ip 211.151.138.3  (从服务器的IP)

priority 50                (优先级,任意定义,但是一定要比主服务器低)    

advert_int 1

authentication {

auth_type PASS      

auth_pass 1111         (默认即可) 

}

track_script {

chk_http_port            (调用检测脚本)

}

virtual_ipaddress {

211.151.137.5         (绑定的虚IP)

}

}

我们编辑 vim   /opt/tools/bin/check_ng.sh

 #!/bin/bash

  N= `ps -C nginx --no-header |wc -l`

   if [ $N -eq 0 ];then

/usr/local/nginx/sbin/nginx

sleep 3

if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then

killall keepalived

fi

fi   

这是一个针对nginx状态进行检测的脚本,第一次nginx服务死掉时,会重新启动,如果Nginx服务依旧没有起来,则杀掉keepalived进程

三:服务器上都启动 keepalived 进程

/etc/init.d/keepalived  start

执行 /sbin/ip  a  我们看一下IP的使用情况

主服务器:

eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000

link/ether 80:c1:6e:71:f1:a2 brd ff:ff:ff:ff:ff:ff

inet 211.151.138.2/27 brd 211.151.138.31 scope global eth1

inet 211.151.138.5/32 scope global eth1

可见虚IP已经挂载上了

同时查看 tail -f /var/log/message  ,  keepalived 日志显示如下:

Jun 28 18:44:25 proxy1 Keepalived_vrrp: Using LinkWatch kernel netlink reflector...

Jun 28 18:44:25 proxy1 Keepalived_vrrp: VRRP sockpool: [ifindex(3), proto(112), fd(10,11)] 

Jun 28 18:44:25 proxy1 Keepalived_vrrp: VRRP_Script(chk_http_port) succeeded

Jun 28 18:44:26 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE

Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE             (这里显示其角色为主服务)

Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.

Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for  211.151.137.5

同时从服务器日志显示为:

Jun 28 18:42:14 proxy2 Keepalived: Starting Keepalived v1.2.2 (06/21,2012)

Jun 28 18:42:14 proxy2 Keepalived: Starting VRRP child process, pid=23588

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering Kernel netlink reflector

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering Kernel netlink command channel

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering gratutious ARP shared channel

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Configuration is using : 65440 Bytes

Jun 28 18:42:14 proxy2 Keepalived_vrrp: Using LinkWatch kernel netlink reflector...

Jun 28 18:42:14 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE         (显示为BACKUP,从)

Jun 28 18:42:14 proxy2 Keepalived_vrrp: VRRP sockpool: [ifindex(3), proto(112), fd(10,11)]      

此时我们关闭主上的keepalived服务,则从的日志变为:

Jun 28 18:43:49 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE

Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE

Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.

Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 211.151.138.5

可见他已经接管了211.151.138.5 这一个虚IP,并且把自己的状态置为了主 MASTER

此时再把原来主上的keepalived进程起来,则其日志为:

Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert

Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE

Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.

Jun 28 18:44:26 proxy2 avahi-daemon[6552]: Withdrawing address record for 211.151.138.5 on eth1

表示接收到了更高权限的消息,于是他把自己的状态置为了从,并且归还 211.151.138.5 这个IP

如此,就实现了高可用 HA