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nginx高可用之keepalived

网友: 文档中心 2022-05-17 23:05:13

                                搭建nginx高可用-keepalived

Keepalived高可用故障切换转移原理

Keepalived高可用服务对之间的故障切换转移，是通过VRRP来实现的。在keepalived服务工作时，主Master节点会不断地向备节点发送（多播的方式）心跳消息，用来告诉备Backup节点自己还活着。当主节点发生故障时，就无法发送心跳的消息了，备节点也因此无法继续检测到来自主节点的心跳了。于是就会调用自身的接管程序，接管主节点的IP资源和服务。当主节点恢复时，备节点又会释放主节点故障时自身接管的IP资源和服务，恢复到原来的备用角色。

方案规划

VIP

IP

nginx端口

主从

10.216.80.2

10.216.80.46

80

MASTER

10.216.80.2

10.216.80.99

80

BACKUP
  1. 安装编译nginx所需要的依赖包

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

可能会出现yum未注册的问题

出现该情况按照以下步骤解决,未出现请忽略

rpm -qa|grep yum|xargs rpm -e --nodeps

  • 安装yum相关安装包

      rpm -ivh python-*

      rpm -ivh yum-*

  • 新建repo配置文件

vi /etc/yum.repos.d/CentOS-Base.repo

进入编辑模式(键盘输入i)粘贴以下配置信息

#CentOS-Base.repo

#

# The mirror system uses the connecting IP address of the client and the

# update status of each mirror to pick mirrors that are updated to and

# geographically close to the client.  You should use this for CentOS updates

# unless you are manually picking other mirrors.

#

# If the mirrorlist= does not work for you, as a fall back you can try the

# remarked out baseurl= line instead.

#

#

[base]

name=CentOS-$7 - Base - 163.com

#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=os

baseurl=http://mirrors.163.com/centos/7/os/$basearch/

gpgcheck=1

gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

 

#released updates

[updates]

name=CentOS-$7 - Updates - 163.com

#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=updates

baseurl=http://mirrors.163.com/centos/7/updates/$basearch/

gpgcheck=1

gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

 

#additional packages that may be useful

[extras]

name=CentOS-$7 - Extras - 163.com

#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=extras

baseurl=http://mirrors.163.com/centos/7/extras/$basearch/

gpgcheck=1

gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

 

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-$7 - Plus - 163.com

baseurl=http://mirrors.163.com/centos/7/centosplus/$basearch/

gpgcheck=1

enabled=0

gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

按esc键 后输入 :wq 保存退出

  • 清楚缓存

yum clean all

  • 安装nginx相关依赖包

中间可能会出现以下情形，输入y继续安装

 

安装nginx(离线)

  • 将nginx-1.10.2.tar.gz安装包移动至/usr/local/src/目录下(可以借助ssh工具)
  • 编译安装nginx
    • cd /usr/local/src/
    • tar -zxvf nginx-1.10.2.tar.gz
    • cd nginx-1.10.2
    • ./configure --prefix=/usr/local/nginx
    • make& make install

为了方便测试，将nginx的index.html稍作修改以便区分

vi /usr/local/nginx/html/index.html

安装keepalived(离线)

  • 将keepalived-2.0.10.tar.gz安装包移动至/usr/local/src/目录
  • 编译安装keepalived
    • cd /usr/local/src/
    • tar -zxvf keepalived-2.0.10.tar.gz
    • cd keepalived-2.0.10
    • ./configure --prefix=/usr/local/keepalived
    • make && make install
  • 将keepalived安装成linux服务
    • 复制keepalived服务脚本到系统服务地址

      • mkdir /etc/keepalived

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

      • cp /usr/local/src/keepalived-2.0.10/keepalived/etc/init.d/keepalived  /etc/init.d/

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

      • ln -s /usr/local/sbin/keepalived /usr/sbin/

    • 可以设置keepalived服务开机启动

      • chkconfig keepalived on

  • 配置说明
    • MASTER节点配置文件(10.216.80.46)

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

 

global_defs {

   router_id 10.216.80.46

}

vrrp_script chk_nginx {

script "/etc/keepalived/nginx_check.sh"

interval 3

weight -20

}

vrrp_instance VI_1 {

    state MASTER

    interface ens33

    virtual_router_id 15

    priority 150

    unicast_src_ip  10.216.80.46

    unicast_peer {

            10.216.80.99

    }   

    advert_int 2

    authentication {

        auth_type PASS

        auth_pass 1234

    }

    virtual_ipaddress {

        10.216.80.2

    }

    track_script {

        chk_nginx

    }

}

  • BACKUP节点配置文件(10.216.80.99)

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

 

global_defs {

   router_id 10.216.80.99

}

vrrp_script chk_nginx {

script "/etc/keepalived/nginx_check.sh"

interval 3

weight -20

}

vrrp_instance VI_1 {

    state BACKUP

    interface ens33

    virtual_router_id 15

    priority 100

    unicast_src_ip  10.216.80.99

    unicast_peer {

            10.216.80.46

    }   

    advert_int 2

    authentication {

        auth_type PASS

        auth_pass 1234

    }

    virtual_ipaddress {

        10.216.80.2

    }

track_script {

        chk_nginx

    }

}

注意事项：

  1. Interface 后面的值是当前使用的网卡信息

查看本机网卡命令 : watch cat /proc/net/dev

哪张网卡的流量变化大一般就是哪张网卡是在线使用的

  • 编写nginx状态检测脚本

vi /etc/keepalived/nginx_check.sh

#!/bin/bash

A=`ps -C nginx --no-header |wc -l`

if [ $A -eq 0 ];then

/usr/local/nginx/sbin/nginx

sleep 2

B=`ps -C nginx --no-header |wc -l`

if [ $B -eq 0 ];then

service keepalived stop

else

exit 0

fi

fi

Keepalived+nginx高可用测试

同时启动10.216.80.46和10.216.80.99的keepalived,nginx会通过检测脚本自动启动

service keepalived start

通过10.216.80.2访问,如下

模拟主节点nginx挂掉后自动重启nginx

/usr/local/nginx/sbin/nginx -s stop

2秒内通过10.216.80.2访问,如下

2秒后通过10.216.80.2访问,如下

nginx恢复

模拟主节点nginx挂掉后自动重启失败,2秒内多次执行命令

/usr/local/nginx/sbin/nginx -s stop

再次通过10.216.80.2访问,如下

自动切换至从节点服务

模拟主节点keepalived宕机 ,关闭keepalived，nginx服务

service keepalived stop

/usr/local/nginx/sbin/nginx -s stop

再次通过10.216.80.2访问,如下

成功切换从节点

模拟主节点keepalived重新启动

service keepalived start

再次通过10.216.80.2访问,如下

成功切换主节点

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