一佳互联
虚拟化容器,大数据,DBA,中间件,监控。

Keepalived 配置详解与主备模式

21 12月
作者:admin|分类:应用管理

keepalived 的几个进程

生产环境使用Keepalived正常运行，共启动3个进程，一个是父进程，负责监控其子进程，一个是VRRP子进程，另外一个是Checkers子进程。

两个子进程都被系统Watchlog看管，两个子进程各自负责自己的事，Healthcheck子进程检查各自服务器的健康状况，如果Healthcheck进程检查到Master上服务不可用了，就会通知本机上的VRRP子进程，让他删除通告，并且去掉虚拟IP，转换为BACKUP状态。

[root@localhost ~]# ps -ef | grep keepalived | grep -v grep
root      16074      1  0 08:37 ?        00:00:00 /usr/sbin/keepalived -D
root      16075  16074  0 08:37 ?        00:00:00 /usr/sbin/keepalived -D
root      16076  16074  0 08:37 ?        00:00:04 /usr/sbin/keepalived -D

 

keepalived的配置文件结构

配置有两部分组成，全局配置和封装实例的部分

全局配置

global_defs {  #第一部分是全局配置。global全局的意思，到加黑结束的地方是全局配置
  notification_email {
#这里面每一行就是一个接收邮箱，可以配置多个人的邮箱，那么出现故障就会发给多个人
    support@test.net
    123@qq.com
 }
    #邮件从哪发出去的，即发送邮件的人，发给notification_email 里面的条目
    notification_email_from luleihhh@163.com
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    #router_id表明该keep alived是做LVS的还是做nginx，只是一个标识而已，相当于标题，写上nginx就说明该leepalived和nginx有关，是实现nginx高可用的
router_id nginx
 }

一般来说keepalived要实现报警不使用上面方式，使用zabbix方式来监控。所以上面部分不写也可以，所以最核心的内容是下面的vrrp

封装实例

上面是global端，第二部分是部分，vrrp段，vrrp_instance是vrrp实例，即要将该机器变为虚拟路由器，这个实例的名字叫VI_1

Stat有两种状态，有关是MASTER一个是BACKUP，要想该机器变为主就写MASTER。

  • Interface表示用户过来访问VIP走哪块网卡
  • virtual_router_id 151，虚拟路由ID，代表虚拟集群它有一个标识，这个标识是唯一的，两台nginx做keepalived时候virtual_router_id的值要是一样的。
  • priority 100：优先级，要保证master的优先级比backup的优先级要大，优先级越高即数字越大会成为master
  • advert_int 5：组播发送的间隔时间，也就是master多长时间给组内的成员发送一个组播信息。可以设置为3，10，但是5秒不长不短。你设置为10，那么你宕机了10秒，即十秒内不发送组播，那么backup还以为master存活着。
  • Authentication：加密，PASS代表通过密码类型加密，密码是1111
  • virtual_ipaddress ：绑定的虚拟VIP，这个IP是局域网内没有使用的IP，用户访问的是VIP不是宿主机的物理ip ，nginx的域名绑定了该VIP（VIP必须和宿主机在一个网段） 

vrrp_script chk_nginx 

 如果nginx异常，仅仅keepalived保持正常，是无法完成系统的正常工作的，因此需要根据业务进程的运行状态决定是否需要进行主备切换。这个时候，我们可以通过编写脚本对业务进程进行检测监控。 

 

keepalived master backup配置

主192.168.179.102

[root@localhost ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id real-server1-nginx
    script_user root
    enable_script_security
 }

vrrp_script chk_nginx {
    script "/data/shell/check_nginx_status.sh"
    interval 2
}


vrrp_instance VI_1 {
     state MASTER
     interface ens32   
     virtual_router_id 151 
     priority 100 
     advert_int 5  
     authentication {
         auth_type  PASS
         auth_pass  1111

     }
     virtual_ipaddress {  
       192.168.179.199
     }
    
      track_script {                                                                                  
       chk_nginx
    }
 }


[root@localhost ~]# nginx
[root@localhost ~]# systemctl start keepalived
[root@localhost ~]# ip a | grep 199
    inet 192.168.179.199/32 scope global ens32


日志/var/log/message
Nov 19 10:51:17 localhost Keepalived_vrrp[45924]: VRRP_Script(chk_nginx) succeeded
Nov 19 10:51:22 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) Transition to MASTER STATE
Nov 19 10:51:27 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) Entering MASTER STATE
Nov 19 10:51:27 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) setting protocol VIPs.
Nov 19 10:51:27 localhost Keepalived_vrrp[45924]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 10:51:27 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens32 for 192.168.179.199

备 192.168.179.103  只需要修改两个地方，state BACKUP  priority 80

[root@localhost ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id real-server2-nginx
    script_user root
    enable_script_security
 }

vrrp_script chk_nginx {
    script "/data/shell/check_nginx_status.sh"
    interval 2
}

vrrp_instance VI_1 {
     state BACKUP
     interface ens32
     virtual_router_id 151
     priority 50
     advert_int 5
     authentication {
         auth_type  PASS
         auth_pass  1111
     }
     virtual_ipaddress {
       192.168.179.199
     }
    
      track_script {                                                                                  
       chk_nginx
    }
 }

[root@localhost ~]# nginx
[root@localhost ~]# systemctl start keepalived

日志如下:
Nov 19 11:00:29 localhost Keepalived[7824]: Opening file '/etc/keepalived/keepalived.conf'.
Nov 19 11:00:29 localhost Keepalived[7825]: Starting Healthcheck child process, pid=7826
Nov 19 11:00:29 localhost Keepalived[7825]: Starting VRRP child process, pid=7827
Nov 19 11:00:29 localhost systemd: Started LVS and VRRP High Availability Monitor.
Nov 19 11:00:29 localhost Keepalived_healthcheckers[7826]: Opening file '/etc/keepalived/keepalived.conf'.
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: Registering Kernel netlink reflector
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: Registering Kernel netlink command channel
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: Registering gratuitous ARP shared channel
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: Opening file '/etc/keepalived/keepalived.conf'.
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) removing protocol VIPs.
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: Using LinkWatch kernel netlink reflector...
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Entering BACKUP STATE
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
Nov 19 11:00:29 localhost Keepalived_vrrp[7827]: VRRP_Script(chk_nginx) succeeded
Nov 19 11:01:02 localhost systemd: Started Session 12 of user root.
Nov 19 11:01:02 localhost systemd: Starting Session 12 of user root.

现在两台配置keepalived算基本配置完毕，只有当backup收不到master的主播包以后才会进行切换，现在master和backup就变成VRRP集群了。（注意这个和nginx没有半毛钱关系，这个高可用是对主机做的，只不过用户访问nginx不是通过宿主机IP去访问nginx，而是通过VIP去访问nginx)

 

keeplaived故障转移测试

master直接把nginx干掉

[root@localhost ~]# pkill nginx

日志如下
Nov 19 11:04:59 localhost Keepalived[45922]: Stopping
Nov 19 11:04:59 localhost systemd: Stopping LVS and VRRP High Availability Monitor...
Nov 19 11:04:59 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) sent 0 priority
Nov 19 11:04:59 localhost Keepalived_vrrp[45924]: VRRP_Instance(VI_1) removing protocol VIPs.
Nov 19 11:04:59 localhost Keepalived_healthcheckers[45923]: Stopped
Nov 19 11:05:00 localhost Keepalived_vrrp[45924]: Stopped

 backup观察现象

#backup日志
Nov 19 11:05:00 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Transition to MASTER STATE
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Entering MASTER STATE
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) setting protocol VIPs.
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens32 for 192.168.179.199
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:05 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens32 for 192.168.179.199


可以看到VIP飘移到backup上面了
[root@localhost ~]# ip a | grep 199
    inet 192.168.179.199/32 scope global ens32

现在将master起来

[root@localhost ~]# nginx
[root@localhost ~]# systemctl start keepalived

日志如下：
Nov 19 11:11:47 localhost Keepalived_vrrp[49324]: Opening file '/etc/keepalived/keepalived.conf'.
Nov 19 11:11:47 localhost Keepalived_vrrp[49324]: VRRP_Instance(VI_1) removing protocol VIPs.
Nov 19 11:11:47 localhost Keepalived_vrrp[49324]: Using LinkWatch kernel netlink reflector...
Nov 19 11:11:47 localhost Keepalived_vrrp[49324]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
Nov 19 11:11:47 localhost Keepalived_vrrp[49324]: VRRP_Script(chk_nginx) succeeded
Nov 19 11:11:50 localhost Keepalived_vrrp[49324]: VRRP_Instance(VI_1) Transition to MASTER STATE
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: VRRP_Instance(VI_1) Entering MASTER STATE
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: VRRP_Instance(VI_1) setting protocol VIPs.
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens32 for 192.168.179.199
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:11:55 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:12:00 localhost Keepalived_vrrp[49324]: Sending gratuitous ARP on ens32 for 192.168.179.199

[root@localhost ~]# ip a | grep 199
    inet 192.168.179.199/32 scope global ens32

再去查看backup状态（ #可以看到backup上是不存在VIP的）

Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:05:10 localhost Keepalived_vrrp[7827]: Sending gratuitous ARP on ens32 for 192.168.179.199
Nov 19 11:11:50 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 50
#可以看到接收到优先级100比自己高的，自己优先级是50，自动退变为backup
Nov 19 11:11:50 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) Entering BACKUP STATE
Nov 19 11:11:50 localhost Keepalived_vrrp[7827]: VRRP_Instance(VI_1) removing protocol VIPs.

[root@localhost ~]# ip a | grep 199
[root@localhost ~]#

如果你的两台nginx上面都有VIP的存在，那么就是防火墙的问题了，防火墙阻挡了。因为master收不到backup的主播（在配置配置文件的时候注意括号和空格）

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