1. 简介

Keepalived的作用是检测web服务器的状态，如果有一台web服务器死机，或工作出现故障，Keepalived将检测到，并将有故障的web服务器从系统中剔除，当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的web服务器。 Keepalived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。

2. 作用

主要用作RealServer的健康状态检查以及LoadBalance主机和BackUP主机之间failover的实现。

3. 安装

1. keepalived安装

下载keepalived官网:http://keepalived.org

1. 安装依赖 su - root yum -y install kernel-devel yum -y install openssl- yum -y install popt-devel yum -y install lrzsz yum -y install openssh-clients

2. 将keepalived解压到/usr/local/src目录下

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

3. 进入到/usr/local/src/keepalived-1.2.19目录

cd /usr/local/src/keepalived-1.2.19

4. 开始configure

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

编译并安装

make && make install

4. 将keepalived添加到系统服务中

1. 拷贝执行文件

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

2. 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

3. 将keepalived文件拷贝到etc下

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

4. 创建keepalived文件夹

mkdir -p /etc/keepalived

5. 将keepalived配置文件拷贝到etc下

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

6. 添加可执行权限

chmod +x /etc/init.d/keepalived

7. 添加keepalived到开机启动

chkconfig --add keepalived

chkconfig keepalived on

8. 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

5. 配置keepalived虚拟IP

修改配置文件： /etc/keepalived/keepalived.conf
#MASTER节点
global_defs {
notification_email {#指定keepalived在发生切换时需要发送email到的对象，一行一个
#acassen@firewall.loc
#failover@firewall.loc
#sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc#指定发件人
#smtp_server 192.168.200.1#指定smtp服务器地址
#smtp_connect_timeout 30 #指定smtp连接超时时间
router_id LVS_DEVEL#运行keepalived机器的一个标识
}
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
}
virtual_server 192.168.56.70 8080 {
delay_loop 6#健康检查时间间隔
lb_algo rr #调度算法rr|wrr|lc|wlc|lblc|sh|dh
lb_kind DR #负载均衡转发规则NAT|DR|RUN
#nat_mask 255.255.255.0 #需要验证
persistence_timeout 1#会话保持时间
protocol TCP#使用的协议
real_server 192.168.56.201 8080 {
weight 10 #默认为1,0为失效
SSL_GET {
url { #检查url，可以指定多个
path /
digest ff20ad2481f97b1754ef3e12ecd3a9cc #检查后的摘要信息
}
url {
path /mrtg/
digest 9b3a0c85a887a256d6939da88aabd8cd
}
connect_timeout 3#连接超时时间
nb_get_retry 3#重连次数
delay_before_retry 3#重连间隔时间
}
}

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
}
}

6. 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

7. 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