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

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 keepalivedglobal_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 keepalivedglobal_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 addr1: 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 forever2: 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/bashcounter=$(ps -C nginx --no-heading|wc -l)if [ "${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    fifi

# 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 keepalivedglobal_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。