利用keepalived实现高可靠（HA）配置nginx 的

1.1.  高可靠概念

HA(High Available), 高可用性集群，是保证业务连续性的有效解决方案，一般有两个或两个以上的节点，且分为活动节点及备用节点。

1.2.  高可靠软件keepalived

keepalive是一款可以实现高可靠的软件，通常部署在2台服务器上，分为一主一备。Keepalived可以对本机上的进程进行检测，一旦Master检测出某个进程出现问题，将自己切换成Backup状态，然后通知另外一个节点切换成Master状态。

1.3.  keepalived安装

下载keepalived官网:http://keepalived.org

 

将keepalived解压到/usr/local/src目录下

tar -zxvf keepalived-1.2.19.tar.gz -C /usr/local/src

 

进入到/usr/local/src/keepalived-1.2.19目录

cd /usr/local/src/keepalived-1.2.19

 

开始configure

./configure--prefix=/usr/local/keepalived

 

#编译并安装

make && make install

 

1.4.  将keepalived添加到系统服务中

拷贝执行文件

cp /usr/local/keepalived/sbin/keepalived/usr/sbin/

将init.d文件拷贝到etc下,加入开机启动项

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

将keepalived文件拷贝到etc下

cp /usr/local/keepalived/etc/sysconfig/keepalived/etc/sysconfig/

创建keepalived文件夹

mkdir -p/etc/keepalived

将keepalived配置文件拷贝到etc下

cp /usr/local/keepalived/etc/keepalived/keepalived.conf/etc/keepalived/keepalived.conf

添加可执行权限

chmod+x/etc/init.d/keepalived

 

##以上所有命令一次性执行：

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ mkdir -p /etc/keepalived cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf chmod +x /etc/init.d/keepalived chkconfig --add keepalived       chkconfig keepalived on

 

添加keepalived到开机启动

chkconfig --add keepalived      

chkconfig keepalived on

 

 

 

 

1.5.  配置keepalived虚拟IP

修改配置文件： /etc/keepalived/keepalived.conf

#MASTER节点

global_defs { } vrrp_instance VI_1 {     state MASTER#指定A节点为主节点 备用节点上设置为BACKUP即可     interface eth0    #绑定虚拟IP的网络接口     virtual_router_id 51   #VRRP组名，两个节点的设置必须一样，以指明各个节点属于同一VRRP组     priority 100#主节点的优先级（1-254之间），备用节点必须比主节点优先级低     advert_int 1  #组播信息发送间隔，两个节点设置必须一样     authentication {    #设置验证信息，两个节点必须一致         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {    #指定虚拟IP, 两个节点设置必须一样 192.168.33.60/24 #如果两个nginx的ip分别是192.168.33.61,,...62，则此处的虚拟ip跟它俩同一个网段即可     } }

 

#BACKUP节点

global_defs { } vrrp_instance VI_1 {     state BACKUP     interface eth0     virtual_router_id 51     priority 99     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }     virtual_ipaddress { 192.168.33.60/24     } }

 

#分别启动两台机器上的keepalived

service keepalived start

测试：

杀掉master上的keepalived进程，你会发现，在slave机器上的eth0网卡多了一个ip地址

查看ip地址的命令：  ip addr

 

1.6.  配置keepalived心跳检查

原理：

Keepalived并不跟nginx耦合，它俩完全不是一家人

但是keepalived提供一个机制：让用户自定义一个shell脚本去检测用户自己的程序，返回状态给keepalived就可以了

 

 

#MASTER节点

global_defs { }   vrrp_script chk_health { script"[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"     interval 1    #每隔1秒执行上述的脚本，去检查用户的程序ngnix     weight -2 }   vrrp_instance VI_1 {     state MASTER     interface eth0     virtual_router_id 1     priority 100     advert_int 2     authentication {         auth_type PASS         auth_pass 1111     }       track_script {         chk_health     }       virtual_ipaddress {         10.0.0.10/24     }   notify_master"/usr/local/keepalived/sbin/notify.sh master" notify_backup"/usr/local/keepalived/sbin/notify.sh backup" notify_fault"/usr/local/keepalived/sbin/notify.sh fault" }

 

#添加切换通知脚本

vi/usr/local/keepalived/sbin/notify.sh

#!/bin/bash   case "$1" in     master)         /usr/local/nginx/sbin/nginx         exit 0     ;; backup) /usr/local/nginx/sbin/nginx -s stop         /usr/local/nginx/sbin/nginx         exit 0     ;;     fault)         /usr/local/nginx/sbin/nginx -s stop         exit 0     ;;     *)         echo 'Usage: notify.sh {master|backup|fault}'         exit 1     ;; esac

 

#添加执行权限

chmod +x/usr/local/keepalived/sbin/notify.sh

global_defs { }   vrrp_script chk_health {     script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"     interval 1     weight -2 }   vrrp_instance VI_1 {     state BACKUP     interface eth0     virtual_router_id 1     priority 99     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }       track_script {         chk_health     }       virtual_ipaddress {         10.0.0.10/24     }          notify_master "/usr/local/keepalived/sbin/notify.sh master"     notify_backup "/usr/local/keepalived/sbin/notify.sh backup"     notify_fault "/usr/local/keepalived/sbin/notify.sh fault" }

 

#在第二台机器上添加notify.sh脚本

#分别在两台机器上启动keepalived

service keepalived start

chkconfig keepalived on