Linux keepalive部署HA高可用環境

一. 高可用環境部署思路

配置兩台Apache環境的服務器，提供相同的web頁面服務，在這兩台Apache服務器上運行keepalive，虛擬出來一個VIP，用戶通過VIP訪問web服務，這樣當一台Apache服務器故障的時候，VIP會飄到另外一台Apache服務器。

二. keepalive部署前准備

1. 安裝開發環境

[root@study01 ~]# yum -y install gcc-* glibc-*  *c++* -y 
[root@study01 ~]# yum -y install openssl-devel

[root@study02 ~]# yum -y install gcc-* glibc-*  *c++* -y 
[root@study02 ~]# yum -y install openssl-devel

  [root@study01 ~]# uname -a
  Linux study01.linux.com 2.6.32-754.el6.x86_64 #1 SMP Tue Jun 19 21:26:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
  [root@study01 ~]# cat /etc/redhat-release
  CentOS release 6.10 (Final)

 

提示：以上是我的server缺少的環境，如果你在以上環境安裝完成后，再安裝keepalive時還有報錯，請根據報錯進行環境補充安裝；

2. 部署Apache基本環境

[root@study01 ~]#/etc/init.d/httpd restart
[root@study01 ~]#chkconfig --level 35 httpd on
[root@study01 ~]#echo "this is linux01" > /var/www/html/index.html

[root@study02 ~]#/etc/init.d/httpd restart
[root@study02 ~]#chkconfig --level 35 httpd on
[root@study02 ~]#echo "this is linux02" > /var/www/html/index.html

 

三. keepalive環境部署

1. 獲取keepalive的安裝鏈接

從官網https://www.keepalived.org/download.html頁面獲取。

2. 使用源碼部署keepalive

[root@study01 ~]# cd /usr/local/src/
[root@study01 src]#wget https://www.keepalived.org/software/keepalived-2.0.20.tar.gz
[root@study01 src]#tar -zxvf keepalived-2.0.20.tar.gz
[root@study01 src]#cd keepalived-2.0.20
[root@study01 src]#./configure --prefix=/usr/local/keepalived
[root@study01 src]#make && make install
[root@study01 src]#cp /usr/local/src/keepalived-2.0.20/keepalived/etc/init.d/keepalived /etc/init.d/
[root@study01 src]#chmod 755 /etc/init.d/keepalived
[root@study01 src]#cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@study01 src]#chmod 755 /usr/sbin/keepalived
[root@study01 src]#cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@study01 src]#mkdir /etc/keepalived
[root@study01 src]#cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

 

提示：第二台linux服務器的keepalive環境部署方法請重復第一台的部署方法。

3. 配置keepalive

[root@study01 ~]# vim /etc/keepalived/keepalived.conf
#以下為第一台環境的keepalive配置內容
! Configuration File for keepalived

global_defs {
   notification_email {
     [e-mail]    #接收告警的郵箱
   }                                     #注意需要單獨配置smtp_send郵箱
   notification_email_from [e-mail]  #發送告警的郵箱
   smtp_server 182.254.38.18   #發送郵件的服務器地址
   smtp_connect_timeout 30
   router_id study01
}

vrrp_script check_httpd {
    script "/usr/bin/killall -0 httpd"   #檢測http服務是否正常
    interval 2
}

vrrp_instance VI_1 {
    state MASTER         #狀態為主，默認搶占
    interface eth0         #監聽的服務接口
    virtual_router_id 51   #主備必須一致，VRRPID
    priority 100          #優先級，越大越優先
    advert_int 1       #心跳報文通告間隔
    authentication {
        auth_type PASS    #keepalive認證類型
        auth_pass 1111    #keepalive認證密碼
    }
    notify_master "/etc/keepalived/master.sh"   #主狀態通告腳本
    notify_backup "/etc/keepalived/backup.sh"   #備狀態通告腳本
    notify_fault "/etc/keepalived/fault.sh"          #故障狀態通過腳本

    track_script {
    check_httpd                 #track http的檢測腳本
    }

    virtual_ipaddress {
　　　　　192.168.31.9                            #虛擬IP的寫法一，不推薦這種寫法。只能用ip add看
        192.168.31.10/24 dev eth0 label eth0:0   #虛擬IP的寫法一，推薦這種寫法。
    }
}    

#以下腳本內容為測試看狀態的簡單編寫方法，實際環境請根據需要編寫；
[root@study01 ~]# cat /etc/keepalived/master.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-state.log
echo "[Master]" >> $LOGFILE
date >> $LOGFILE
[root@study01 ~]# cat /etc/keepalived/backup.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-state.log
echo "[Backup]" >> $LOGFILE
date >> $LOGFILE
[root@study01 ~]# cat /etc/keepalived/fault.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-state.log
echo "[Fault]" >> $LOGFILE
date >> $LOGFILE
[root@study01 ~]#

提示：第二台keepalive配置方法同第一台一樣，注意角色定義為BACKUP，優先級要低於角色Master的優先級；

vi /etc/keepalived/keepalived.conf    # 參照下面配置修改配置文件

! Configuration File for keepalived

global_defs {
    notification_email {
        [e-mail]    # 設置報警郵件地址，可以設置多個，每行一個
    }
    # 需開啟本機的sendmail服務
    notification_email_from [e-mail]    # 設置郵件的發送地址
    smtp_server 127.0.0.1    # 設置smtp server地址
    smtp_connect_timeout 30    # 設置連接smtp server的超時時間
    router_id LVS_DEVEL    # 表示運行keepalived服務器的一個標識。發郵件時顯示在郵件主題的信息
    vrrp_skip_check_adv_addr
    vrrp_strict
    vrrp_garp_interval 0
    vrrp_gna_interval 0
}

vrrp_instance VI_1 { # 定義的VRRP熱備實例
    state MASTER    # 標示狀態為MASTER 備份機為BACKUP
    interface eth0     # 承載VIP地址的物理接口
    virtual_router_id 51    # 虛擬路由器的id號，每個熱備組保持一致
    priority 100    # MASTER權重要高於BACKUP 比如BACKUP為99
    advert_int 1    # 通告間隔秒數，（心跳頻率）  注意通告的組播地址224.0.0.18
    # mcast_src_ip 172.16.1.99    # Master服務器IP，如果是備份機請填寫備份機的IP

    authentication {
        auth_type PASS    # 主從服務器認證類型
        auth_pass 1111    # 認證字串
    }
    virtual_ipaddress {
        172.16.1.100    # 可以多個虛擬IP，換行即可
    }

    # 虛擬服務器 80端口的配置
    virtual_server 172.16.1.100 80 {
        delay_loop 6    # 每隔6秒查詢realserver狀態
        lb_algo rr    # lvs 算法
        lb_kind DR    # Direct Route
        nat_mask 255.255.255.0
        persistence_timeout 50    # 同一IP的連接50秒內被分配到同一台realserver
        protocol TCP    # 用TCP協議檢查realserver狀態

        # 實際服務器的IP和端口
        real_server 172.16.1.101 80 {
            weight 3
            TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            }
        }

        real_server 172.16.1.102 80 {
            weight 3
            TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            }
        }
    }
}

 

4. 啟動keepalive服務

[root@study01 ~]#chkconfig --level 35 keepalived on
[root@study01 ~]#/etc/init.d/keepalived restart
[root@study02 ~]#chkconfig --level 35 keepalived on
[root@study02 ~]#/etc/init.d/keepalived restart

Mar 15 17:26:35 study01 Keepalived[8582]: Starting Keepalived v2.0.20 (01/22,2020)
Mar 15 17:26:35 study01 Keepalived[8582]: Running on Linux 2.6.32-754.el6.x86_64 #1 SMP Tue Jun 19 21:26:04 UTC 2018 (built for Linux 2.6.32)
Mar 15 17:26:35 study01 Keepalived[8582]: Command line: 'keepalived' '-D'
Mar 15 17:26:35 study01 Keepalived[8582]: Opening file '/etc/keepalived/keepalived.conf'.
Mar 15 17:26:35 study01 Keepalived[8583]: Starting VRRP child process, pid=8585
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Registering Kernel netlink reflector
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Registering Kernel netlink command channel
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Opening file '/etc/keepalived/keepalived.conf'.
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: WARNING - default user 'keepalived_script' for script execution does not exist - please create.
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: SECURITY VIOLATION - scripts are being executed but script_security not enabled.
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Assigned address 192.168.31.5 for interface eth0
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Assigned address fe80::a00:27ff:fe8c:afb for interface eth0
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: Registering gratuitous ARP shared channel
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: (VI_1) removing VIPs.
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: VRRP sockpool: [ifindex(2), family(IPv4), proto(112), unicast(0), fd(11,12)]
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: VRRP_Script(check_httpd) succeeded
Mar 15 17:26:35 study01 Keepalived_vrrp[8585]: (VI_1) Entering BACKUP STATE
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: (VI_1) Receive advertisement timeout
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: (VI_1) Entering MASTER STATE
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: (VI_1) setting VIPs.
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: (VI_1) Sending/queueing gratuitous ARPs on eth0 for 192.168.31.10
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10
Mar 15 17:26:39 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10
Mar 15 17:26:44 study01 Keepalived_vrrp[8585]: Sending gratuitous ARP on eth0 for 192.168.31.10

Mar 15 17:28:38 study02 Keepalived_vrrp[6661]: VRRP sockpool: [ifindex(2), family(IPv4), proto(112), unicast(0), fd(11,12)]
Mar 15 17:28:38 study02 Keepalived_vrrp[6661]: VRRP_Script(check_httpd) succeeded
Mar 15 17:28:38 study02 Keepalived_vrrp[6661]: (VI_1) Entering BACKUP STATE

 

四. 驗證高可用

[root@study01 ~]#/etc/init.d/httpd stop

#觀察第一台和第二台linux server的keepalive日志，會發現server01會從master變為fault狀態，server02會從backup狀態變為master狀態，此時訪問web頁面訪問的變成了第二台服務器的web頁面；


[root@study01 ~]#/etc/init.d/httpd start

#觀察第一台和第二台linux server的keepalive日志，會發現server01會從fault變為backup，然后再變為master狀態，server02會從master狀態變為backup狀態，此時訪問web頁面訪問的變成了第一台服務器的web頁面；

至此實現了高可用功能，但是你有沒有發現這樣主機恢復是會搶占服務的，實際業務要求穩定性高，不希望主恢復時主動搶占，那么請看第五部分的更多介紹。

提示：如果要看VIP，需要使用“ip add”命令。

五. keepalive主備切換介紹

1. 通過vrrp_script實現對資源的監控

#1. 通過killall命令監控服務的運行狀態
vrrp_script check_httpd {
    script "/usr/bin/killall -0 httpd"   #進程存在$?會返回0，否則$?會返回1
    interval 2
}
……(track部分省略)……

#2. 檢測端口允許狀態
vrrp_script check_httpd {
    script "</dev/tcp/127.0.0.1/80"   #對本機的80端口檢測
    interval 2            #監控間隔2秒一次
    fall 2                            #如果失敗兩次則認為失敗
    rise 1                          #如果成功一次則認為成功
}
……(track部分省略)……

#3. 通過shell語句進行狀態監控
vrrp_script check_httpd {
    script "if [ -f /var/run/httpd/httpd.pid ]; then exit 0; else exit 1; fi"
    interval 2
}
……(track部分省略)……

#4. 通過腳本進行服務狀態監控 
vrrp_script check_httpd {
    script "/etc/keepalived/check_mysql.sh"  #腳本根據需要寫
    interval 2
}
……(track部分省略)……        

 

2. master和backup的角色切換

• 角色指定為master（master的優先級要配置的比backup大），master恢復時一定會搶占（默認搶占），想不搶占需要將所有的角色配置為backup（通過優先級決定誰是主角色），並指定nopreempt參數。
• 實際上決定keepalive狀態的並不是角色state定義的master或者backup，而是priority和weight計算后決定的。weight可以配置為正數或者負數。
  • weight配置為正數時，如果檢測成功，那么master節點的優先級為priority和weight之和，如果檢測失敗，那么master節點的優先級為priority；
  • weight配置為負數時，如果檢測成功，那么master節點的優先級仍為priority，如果檢測失敗那么master節點的優先級為priority減去weight；
  • 配置weight有個准則，那就是weight無論正負，weight的絕對值要大於master與backup節點的priority的差。