keepalived+nginx（主从模式）

1.搭建keepalived+nginx

实现双机热备+负载均衡（主从模式）

lb-01:172.21.3.186 nginx+keepalived-master

lb-02:172.21.3.187 nginx+keepalived-backup

VIP：172.21.3.194　

2.下载安装软件

分别在两台主机172.21.3.186，172.21.3.187上安装依赖和下载安装包

* 安装依赖包

# yum -y install gcc gcc+ gcc-c++ pcre-devel zlib-devel openssl-devel  popt-devel

下载

keepalived

安装包

# wget http://www.keepalived.org/software/keepalived-1.1.17.tar.gz

下载

nginx

安装包

# wget http://nginx.org/download/nginx-1.8.1.tar.gz[/code] 
3.安装nginx
2台主机都使用默认配置进行安装

* 解压

# tar -zxvf ./nginx-1.8.1.tar.gz


安装软件

注：源码的安装一般由3个步骤组成:配置
configure
、编译
make
、安装
make install


# cd ./nginx-1.8.1
# ./configure && make && make install
# whereis nginx    #可查看安装目录


运行nginx

# cd /usr/local/nginx/sbin/
# ./nginx


测试nginx是否正常启动

# curl http://172.21.3.186 | grep nginx
<title>Welcome to nginx!</title>


4.安装keepalived
解压

# tar -zxvf ./keepalived-1.1.17.tar.gz


安装

# cd ./keepalived-1.1.17
# ./configure --prefix=/usr/local/keepalived
# make && make install


添加配置文件、设置
keepalived
为自启服务

#   mkdir /etc/keepalived
#   cp /usr/local/keepalived/etc/keepalived/keepalived.conf    /etc/keepalived/keepalived.conf
#   cp /usr/local/keepalived/etc/rc.d/init.d/keepalived  /etc/init.d/
#   cp /usr/local/keepalived/etc/sysconfig/keepalived  /etc/sysconfig/
#   cp /usr/local/keepalived/sbin/keepalived  /usr/sbin/
#   chkconfig --level 2345 keepalived on


修改配置文件

配置172.21.3.186文件(Master):

# vim /etc/keepalived/keepalived.conf   #修改配置文件
! Configuration File for keepalived

global_defs {
router_id NGINX_DEMO
}

vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 101
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.21.3.194
}
}


修改172.21.3.187文件(Backup):

# vim /etc/keepalived/keepalived.conf   #修改配置文件
! Configuration File for keepalived

global_defs {
router_id NGINX_DEMO
}

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 {
172.21.3.194
}
}


启动服务

#   service  keepalived   start


使用
ip addr
检查虚拟ip

# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:0c:29:04:89:2c brd ff:ff:ff:ff:ff:ff
inet 172.21.3.186/24 brd 172.21.3.255 scope global eth0
inet 172.21.3.194/32 scope global eth0     #看这里，已经可以看到虚拟ip了
inet6 fe80::20c:29ff:fe04:892c/64 scope link
valid_lft forever preferred_lft forever


5.让keepalived监控nginx状态
经过前面的配置，如果
master
主服务的
keepalived
停止服务，
slave
从服务会自动接管VIP对外服务。一旦主服务器的
keepalived
恢复，会重新接管VIP。但这并不是我们需要的，我们需要当
nginx
停止服务的时候能自动切换。我们需要使用keepalived来运行监控脚本。

创建监听nginx状态脚本

#  vim /opt/chk_nginx.sh


#!/bin/bash
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "0" ]; then
/usr/local/nginx/sbin/nginx
sleep 2
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "0" ]; then
/etc/init.d/keepalived stop
fi
fi


# chmod 755 /opt/chk_nginx.sh


同时修改主从服务器上的
keepalived
配置文件

! Configuration File for keepalived

global_defs {
router_id NGINX_DEVEL
}

vrrp_script chk_http_port  {   #检测nginx服务是否在运行。
script "/opt/chk_nginx.sh" #这里通过脚本监测
interval 2                 #脚本执行间隔，每2s检测一次
weight -5                  #脚本结果返回非零则优先级-5
fall 2                     #监测连续失败2次，才算失败会用weight减少优先级
rise 1                     #检测1次成功就算成功
}

vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 101
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.21.3.194
}
track_script  {   #执行监控的服务。
chk_http_port        #引用VRRP脚本，
}
}


6.测试
打开网址输入VIP地址就可以了



测试关闭172.21.3.186中的
nginx
服务

# killall nginx




可以看到我们在
keepalived
中的监控脚本启动正常。

测试关闭172.21.3.186中的
keepalived
服务

# killall keepalived


再次打开网址



说明我们配置热备成功。