Keepalived 高可用

最新推荐文章于 2022-11-10 22:36:48 发布

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最新推荐文章于 2022-11-10 22:36:48 发布

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分类专栏： keepalived 文章标签： keepalived 高可用

本文链接：https://blog.youkuaiyun.com/qq_36327717/article/details/103242482

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本文介绍了Keepalived作为主流高可用软件的功能和工作原理，包括监控检测和VRRP冗余协议。通过Core、Check和Vrrp等模块，Keepalived能实现健康检查和虚拟路由器冗余，确保服务的高可用性。详细讲述了Keepalived的安装配置步骤，以及模拟故障转移的检测脚本。

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Keepalived介绍
Keepalived安装配置

Keepalived介绍

web架构的高可用方案：

基于SHELL脚本实现高可用
基于Keepalived软件实现高可用（主流的高可用软件）
基于Heartbeat软件实现高可用（最早期使用软件）

Keepalived 是一个类似于工作在 layer3, 4 & 7 交换机制的软件，Keepalived 软件有两种功能，分别是

监控检查
VRRP 冗余协议

Keepalived监控检测功能检测方案：可以以如下三种方式去检测，如果发现WEB网站、数据库服务器宕机或者异常，可以从服务列表（服务池）移除该服务器，等待服务器恢复以后，Keepalived可以将服务器加入到服务列表（服务池）.
三种方式检测案例如下：

Keepalived可以网络层工作方式，以IP形式去监控客户端（网站、数据库）
Keepalived可以传输层工作方式，以IP+端口形式去监控客户端（网站、数据库）
Keepalived可以应用层工作方式，以HTTP、FTP等协议形式去监控客户端（网站、数据库）

Keepalived高可用软件模块剖析：

Core，是keepalived的核心，负责主进程的启动和维护，全局配置文件的加载解析等。
Check，负责healthchecker(健康检查)，包括了各种健康检查方式，以及对应的配置的解析包括LVS的配置解析
Vrrp，VRRPD子进程，VRRPD子进程就是来实现VRRP协议
Libipfwc，iptables(ipchains)库，配置LVS会用到
Libipvs，虚拟服务集群，配置LVS会使用。

Keepalived可以实现VRRP冗余功能，冗余功能（高可用功能），将2台路由器（服务器）组成冗余集群，同一时刻一台服务器对外提供服务，当一台服务器宕机以后，会自动切换至另外服务器

VRRP冗余技术剖析：

虚拟路由器冗余技术，严格来讲不仅仅属于Keepalived软件的；
基于VRRP技术可以将多台路由器（主机）组成一个虚拟路由器集群；
虚拟路由器集群中，根据优先级选举产生：Master和Backup，Master拥有特殊权限：绑定VIP（虚拟IP），同时对外响应用户的请求或者转发用户请求；
Master路由器（主机）定时向集群组内发送组播包（组播地址：224.0.0.18），BACKUP接收组播包，一旦接收不到（认为Master宕机），其他BACKUP会根据优先级重新选举Master；
在一组虚拟路由器集群中，不管谁是MASTER，对外都是相同的MAC和VIP。

回到目录

Keepalived安装配置

安装

yum install keepalived* -y

修改配置

[root@localhost ~]# mv /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@localhost ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived 
global_defs { 
  notification_email { 
      jeffding1993@outlook.com
 } 
    notification_email_from root@localhost.localdomain
    smtp_server 127.0.0.1 
    smtp_connect_timeout 30 
    router_id LVS_DEVEL 
 } 
vrrp_script chk_nginx { 
    script  "/data/sh/check_nginx.sh" 
    interval 2 
    weight 2 
} 
#VIP1 192.168.197.18 
vrrp_instance VI_1 { 
     state MASTER 
     interface eno16777736
     lvs_sync_daemon_inteface eno16777736
     virtual_router_id 151   # 同一局域网vr_id 为唯一，表示为一个虚拟路由器组
     priority 100 
     advert_int 5 
     #nopreempt   #表示不抢占vip
     authentication { 
         auth_type  PASS 
         auth_pass  1111 
     } 
     virtual_ipaddress { 
         192.168.197.18 
     } 
     track_script { 
     chk_nginx 
    } 
}
#VIP2 192.168.197.19
vrrp_instance VI_2 { 
     state MASTER
     interface eno16777736
     lvs_sync_daemon_inteface eno16777736
     virtual_router_id 152   # 同一局域网vr_id 为唯一，表示为一个虚拟路由器组
     priority 100
     advert_int 5 
     #nopreempt   #表示不抢占vip
     authentication { 
         auth_type  PASS 
         auth_pass  1111 
     } 
     virtual_ipaddress { 
         192.168.197.19 
     } 
     track_script { 
     chk_nginx 
    } 
}

启动keepalived服务

[root@localhost ~]# systemctl restart keepalived
[root@localhost ~]# ps -ef | grep keep
root     15283     1  0 19:41 ?        00:00:00 /usr/sbin/keepalived -D
root     15284 15283  0 19:41 ?        00:00:00 /usr/sbin/keepalived -D
root     15285 15283  0 19:41 ?        00:00:00 /usr/sbin/keepalived -D
root     15296  1078  0 19:41 pts/0    00:00:00 grep --color=auto keep

查看日志，确定keepalived是否启动成功

[root@localhost ~]# tail -fn 100 /var/log/messages
Nov 25 19:41:33 localhost Keepalived_vrrp[15285]: VRRP_Instance(VI_2) Transition to MASTER STATE
Nov 25 19:41:38 localhost Keepalived_vrrp[15285]: VRRP_Instance(VI_2) Entering MASTER STATE
Nov 25 19:41:38 localhost Keepalived_vrrp[15285]: VRRP_Instance(VI_2) setting protocol VIPs.

使用ip命令查看

[root@localhost ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:58:02:17 brd ff:ff:ff:ff:ff:ff
    inet 192.168.197.10/24 brd 192.168.197.255 scope global noprefixroute eno16777736
       valid_lft forever preferred_lft forever
    inet 192.168.197.18/32 scope global eno16777736
       valid_lft forever preferred_lft forever
    inet 192.168.197.19/32 scope global eno16777736
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe58:217/64 scope link 
       valid_lft forever preferred_lft forever

结果
将配置文件复制到其他分布式节点中

[root@localhost ~]# scp -r /etc/keepalived/keepalived.conf root@192.168.197.11:/etc/keepalived/
The authenticity of host '192.168.197.11 (192.168.197.11)' can't be established.
ECDSA key fingerprint is SHA256:CM67EHgLjgq8lZAVFvhI3puTU2ESgWbMLxreTjPDNmk.
ECDSA key fingerprint is MD5:d0:17:35:b1:34:c8:15:22:b4:7f:09:71:29:e6:e7:e1.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.197.11' (ECDSA) to the list of known hosts.
root@192.168.197.11's password: 
keepalived.conf                                                                                                                      100% 1132     1.6MB/s   00:00

# 修改配置文件
[root@localhost ~]# cat /etc/keepalived/keepalived.conf 
! Configuration File for keepalived 
global_defs { 
  notification_email { 
      jeffding1993@outlook.com
 } 
    notification_email_from root@localhost.localdomain
    smtp_server 127.0.0.1 
    smtp_connect_timeout 30 
    router_id LVS_DEVEL 
 } 
vrrp_script chk_nginx { 
    script  "/data/sh/check_nginx.sh" 
    interval 2 
    weight 2 
} 
#VIP1 192.168.197.18 
vrrp_instance VI_1 { 
     state BACKUP  # 状态修改为MASTER
     interface ens33
     lvs_sync_daemon_inteface ens33
     virtual_router_id 151 
     priority 80 # 优先级要比MASTER的优先级低
     advert_int 5 
     #nopreempt 
     authentication { 
         auth_type  PASS 
         auth_pass  1111 
     } 
     virtual_ipaddress { 
         192.168.197.18 
     } 
     track_script { 
     chk_nginx 
    } 
}
#VIP2 192.168.197.19
vrrp_instance VI_2 { 
     state BACKUP
     interface ens33
     lvs_sync_daemon_inteface ens33
     virtual_router_id 152 
     priority 80 
     advert_int 5 
     #nopreempt 
     authentication { 
         auth_type  PASS 
         auth_pass  1111 
     } 
     virtual_ipaddress { 
         192.168.197.19 
     } 
     track_script { 
     chk_nginx 
    } 
}

查看日志

[root@localhost ~]# tail -fn 100 /var/log/messages
Nov 25 20:02:28 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_1) Entering BACKUP STATE
Nov 25 20:02:28 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_2) Entering BACKUP STATE

模拟故障转移

# 192.168.197.10
[root@localhost ~]# service keepalived stop
Redirecting to /bin/systemctl stop keepalived.service

# 192.168.197.11
[root@localhost ~]# tail -fn 100 /var/log/messages
Nov 25 20:07:14 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_1) Transition to MASTER STATE
Nov 25 20:07:14 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_2) Transition to MASTER STATE
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_1) Entering MASTER STATE
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_1) setting protocol VIPs.
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.18
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_2) Entering MASTER STATE
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_2) setting protocol VIPs.
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: Sending gratuitous ARP on ens33 for 192.168.197.19
Nov 25 20:07:19 localhost Keepalived_vrrp[15381]: VRRP_Instance(VI_2) Sending/queueing gratuitous ARPs on ens33 for 192.168.197.19

检测脚本内容如下

#!/bin/bash
#auto	check	nginx	process 
#by	author jeff 
#yum install psmisc -y
killall -0 nginx
if [[ $? -ne 0 ]];then
/etc/init.d/keepalived stop
#centos7
#systemctl stop keepalived
fi

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