搭建nginx高可用-keepalived

Keepalived高可用故障切換轉移原理

Keepalived高可用服務對之間的故障切換轉移，是通過VRRP來實現的。在keepalived服務工作時，主Master節點會不斷地向備節點發送（多播的方式）心跳訊息，用來告訴備Backup節點自己還活著。當主節點發生故障時，就無法傳送心跳的訊息了，備節點也因此無法繼續檢測到來自主節點的心跳了。於是就會呼叫自身的接管程式，接管主節點的IP資源和服務。當主節點恢復時，備節點又會釋放主節點故障時自身接管的IP資源和服務，恢復到原來的備用角色。

方案規劃

VIP	IP	nginx埠	主從
10.216.80.2	10.216.80.46	80	MASTER
10.216.80.2	10.216.80.99	80	BACKUP

1. 安裝編譯nginx所需要的依賴包

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

可能會出現yum未註冊的問題

出現該情況按照以下步驟解決,未出現請忽略

• 解除安裝yum相關安裝包

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

• 安裝yum相關安裝包

      rpm -ivh python-*

      rpm -ivh yum-*

• 新建repo配置檔案

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

進入編輯模式(鍵盤輸入i)貼上以下配置資訊

#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鍵 後輸入 :wq 儲存退出

• 清楚快取

yum clean all

• 安裝nginx相關依賴包

中間可能會出現以下情形，輸入y繼續安裝

 

安裝nginx(離線)

• 將nginx-1.10.2.tar.gz安裝包移動至/usr/local/src/目錄下(可以藉助ssh工具)
• 編譯安裝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
  • 

為了方便測試，將nginx的index.html稍作修改以便區分

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

安裝keepalived(離線)

• 將keepalived-2.0.10.tar.gz安裝包移動至/usr/local/src/目錄
• 編譯安裝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
  • 
• 將keepalived安裝成linux服務
  • 複製keepalived服務指令碼到系統服務地址

    • 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/

  • 可以設定keepalived服務開機啟動

    • chkconfig keepalived on

• 配置說明
  • MASTER節點配置檔案(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節點配置檔案(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

    }

}

注意事項：

1. Interface 後面的值是當前使用的網絡卡資訊

檢視本機網絡卡命令 : watch cat /proc/net/dev

哪張網絡卡的流量變化大一般就是哪張網絡卡是線上使用的

• 編寫nginx狀態檢測指令碼

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高可用測試

同時啟動10.216.80.46和10.216.80.99的keepalived,nginx會通過檢測指令碼自動啟動

service keepalived start

通過10.216.80.2訪問,如下

模擬主節點nginx掛掉後自動重啟nginx

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

2秒內通過10.216.80.2訪問,如下

2秒後通過10.216.80.2訪問,如下

nginx恢復

模擬主節點nginx掛掉後自動重啟失敗,2秒內多次執行命令

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

再次通過10.216.80.2訪問,如下

自動切換至從節點服務

模擬主節點keepalived宕機 ,關閉keepalived，nginx服務

service keepalived stop

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

再次通過10.216.80.2訪問,如下

成功切換從節點

模擬主節點keepalived重新啟動

service keepalived start

再次通過10.216.80.2訪問,如下

成功切換主節點