Keepalived + Nginx实现高可用 Web负载均衡

Keepalived+Nginx实现

Keepalived简要介绍

Keepalived 是一种高性能的服务器高可用或热备解决方案，Keepalived可以用来防止服务器单点故

障的发生，通过配合 Nginx可以实现 web前端服务的高可用。

Keepalived 以 VRRP 协议为实现基础，用 VRRP 协议来实现高可用性(HA)。VRRP(Virtual Router

Redundancy Protocol)协议是用于实现路由器冗余的协议，VRRP协议将两台或多台路由器设备虚拟成一个

设备，对外提供虚拟路由器 IP(一个或多个)，而在路由器组内部，如果实际拥有这个对外 IP 的路由器如

果工作正常的话就是 MASTER，或者是通过算法选举产生，MASTER实现针对虚拟路由器 IP的各种网络功能，

如 ARP请求，ICMP，以及数据的转发等；其他设备不拥有该虚拟 IP，状态是 BACKUP，除了接收 MASTER的

VRRP状态通告信息外，不执行对外的网络功能。当主机失效时，BACKUP将接管原先 MASTER的网络功能。

VRRP协议使用多播数据来传输 VRRP数据，VRRP数据使用特殊的虚拟源 MAC地址发送数据而不是自身

网卡的 MAC地址，VRRP 运行时只有 MASTER 路由器定时发送 VRRP 通告信息，表示 MASTER 工作正常以及虚

拟路由器 IP(组)，BACKUP 只接收 VRRP 数据，不发送数据，如果一定时间内没有接收到 MASTER 的通告信

息，各 BACKUP将宣告自己成为 MASTER，发送通告信息，重新进行 MASTER选举状态。

开始搭建：

节点： 安装

Cluster1 192.168.152.11     Keepalived  Nginx          CentOs6.8
Cluster1 192.168.152.12 Keepalived  Nginx          CentOs6.8

 下载 Keepalived v1.2.18 和Nginx 1.10.2

点击这里下载Keepalived   点击这里下载Nginx

首先 安装需要的环境

yum install gcc gcc-c++ make automake autoconf libtool pcre pcre-devel zlib zlib-devel
openssl openssl-devel

执行 下载 编译 Nginx 所需的依赖包

上传到Linux Nginxtar包 

tar -zxvf nginx-1.10.2.tar.gz
cd nginx-1.10.2
./configure --prefix=/soft/install/nginx
make && make install

执行上面代码 进行编译

成功以后 开始配置Nginx

vim /soft/install/nginx/conf/nginx.conf

user  root;

将用户改为 root

修改html下的index.html页面 

Cluster2 机器同理

启动 Nginx
/usr/local/nginx/sbin/nginx
重启 Nginx
/usr/local/nginx/sbin/nginx -s reload

访问

Nginx安装成功

安装Keepalived

上传并编译

tar -zxvf keepalived-1.2.18.tar.gz
cd keepalived-1.2.18
./configure --prefix=/soft/install/keepalived
make && make install

将 keepalived安装成 Linux系统服务：

因为没有使用 keepalived的默认路径安装（默认是/usr/local）,安装完成之后，需要做一些工作

复制默认配置文件到默认路径

mkdir /etc/keepalived
cp /soft/install/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

复制 keepalived服务脚本到默认的地址

cp /soft/install/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /soft/install/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /soft/install/sbin/keepalived /usr/sbin/
ln -s /soft/install/keepalived/sbin/keepalived /sbin/

设置 keepalived服务开机启动

chkconfig keepalived on

修改 Keepalived （Master）192.168.152.11配置文件

vi /etc/keepalived/keepalived.conf

内容为：

! Configuration File for keepalived

global_defs {
   router_id cluster1
}

vrrp_script chk_nginx {
        script "/etc/keepalived/nginx_check.sh"
        interval 60
        weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    mcast_src_ip 192.168.152.11
    priority 100
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        chk_nginx
    }
    virtual_ipaddress {
        192.168.152.66
    }
}

vi /etc/keepalived/keepalived.conf

配置BACKUP (192.168.152.12)

! Configuration File for keepalived

global_defs {
   router_id cluster2
}

vrrp_script chk_nginx {
        script "/etc/keepalived/nginx_check.sh"
        interval 2
        weight -20
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    mcast_src_ip 192.168.152.12
    priority 90
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        chk_nginx
    }
    virtual_ipaddress {
        192.168.152.66
    }
}

编辑检查脚本

/etc/keepalived/nginx_check.sh

#!/bin/bash

cd /soft/data/
failcount=0
runlog=nginx_runlog.txt

for((i=1;i<=6;i++));
do
        result=`curl http://127.0.0.1/isok.html`

        time=`date +%F\ %k:%M:%S`
        error=false
        if [ "$result" != "ok" ] ; then
                echo "=================$time====================" >> $runlog
                                failcount=`expr $failcount + 1`
                                echo "nginx doesn't work!" >> $runlog
                echo " ================================" >> $runlog
        else
                break
        fi

        if test $failcount -gt 5 ; then
                echo "\n==================$time=====================\n\n" >> $runlog
                echo "restart nignx..." >> $runlog
                echo "     ================================" >> $runlog

                        #关闭
                        /soft/install/nginx/sbin/nginx -s stop

                        if [ -s /soft/install/nginx/logs/nginx.pid ] ; then
                                pid=`cat /soft/install/nginx/logs/nginx.pid`
                                kill -quit $pid
                        fi

                        #启动
                        /soft/install/nginx/sbin/nginx

                        sleep 10

                        result=`curl http://127.0.0.1/isok.html`

                        if [ "$result" != "ok" ] ; then
                                 killall keepalived
                        fi
        fi
done

添加isok.html

vim /soft/install/nginx/html/isok.html 
ok

给脚本权限

chmod +x /etc/keepalived/nginx_check.sh

启动 Keepalived

service keepalived start
Starting keepalived: [ OK ]

Keepalived服务管理命令：

停止：service keepalived stop

启动：service keepalived start

重启：service keepalived restart

查看状态：service keepalived status

Ok 配置已经结束了 随便检测

到此结束。。。Keepalived + Nginx双机热备就OK了