Keepalived+Haproxy实现高可用负载均衡

高可用负载（主备节点）部署步骤

完成下图一个简单的高可用负载机制：

1.拷贝keepalived-1.2.19.tar.gz至Linux的/home目录（也可以是其它目录）

2.解压并安装keepalived：

tar -zxvf keepalived-1.2.19.tar.gz
yum install popt-devel
yum -y install openssl-devel
cd keepalived-1.2.19
./configure
make && make install

这样keepalived编译及安装完成！

3.拷贝并复制keepalived：

cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived
cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/sbin/keepalived /usr/sbin/

上传并覆盖keepalived.conf至/etc/keepalived
备注：keepalived.conf详见步骤4

上传check_haproxy.sh至/etc/keepalived
备注：check_haproxy.sh配置文件内容如下：

#!/bin/bash
A=`ps -C haproxy --no-header |wc -l`
if [ $A -eq 0 ];then
/usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/cfg/haproxy.cfg
sleep 3
if [ `ps -C haproxy --no-header |wc -l` -eq 0 ];then
/etc/init.d/keepalived stop
fi
fi

4.修改keepalived.conf配置文件：

! Configuration File for keepalived

global_defs {
   notification_email {
        [e-mail]  # 修改成可用的收件人地址，可为多个
   }
 notification_email_from [e-mail]  # 修改成可用的发件人地址
   smtp_server mail.iflytek.com  # 修改成可用的邮箱代理地址
   smtp_connect_timeout 30
   router_id keepalived
}
vrrp_script chk_http_port {
     script "/etc/keepalived/check_haproxy.sh"   # 修改成Haproxy监控脚本路径
     interval 2   # 检查间隔时间，单位：秒
}
vrrp_instance VI_MASTER {
state MASTER  # 修改成MASTER，意味着该服务器为主节点；若修改为BACKUP，则为备用节点，即当主机宕掉，从机接管
    interface eth0
    virtual_router_id 51
    priority 150
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
             chk_http_port
    }
    virtual_ipaddress {
192.168.1.1  # 修改成可用的虚拟IP
    }
}

5.解压haproxy-1.5.12并上传至/usr/local

6.修改/usr/local/haproxy/cfg配置文件haproxy.cfg：

global
      daemon
      nbproc 1
      group nobody
      user nobody
      maxconn 102400
      ulimit-n 204821
chroot /usr/local/haproxy

defaults
      mode tcp
      maxconn 102400
      retries 3
      option redispatch
      option abortonclose
      timeout connect 600s
      timeout client 600s
      timeout server 600s

listen interface
bind 0.0.0.0:8001
      balance leastconn
      mode http
      server interface1 192.168.85.100:8001 weight 1 maxconn 102400 check inter 10s
      server interface2 192.168.85.101:8001 weight 1 maxconn 102400 check inter 10s

listen engine
bind 0.0.0.0:18006
      balance leastconn
      mode tcp
      server engine1 192.168.85.100:18006 weight 1 maxconn 102400 check inter 10s
      server engine2 192.168.85.101:18006 weight 1 maxconn 102400 check inter 10s

至此完成Haproxy配置修改！

7.运行如下命令，启动Haproxy运行：

/etc/init.d/keepalived start

8.测试：

telnet 192.168.1.1 8001
telnet 192.168.1.1 18006

依次使用虚拟IP+路由端口的形式验证对应端口是否可用！

说明：对于从机部署，与主机部署一致。这里说明一下：对于HA，只会使用主节点，仅当主节点挂掉，才会切换到从节点！