当前位置: 首页 >> K8s >> 【双机】Keepalived双机热备(HA) >> 正文

【双机】Keepalived双机热备(HA)

9年前 (2015-09-09)     作者:Jiaozn     分类:K8s     阅读次数:4678     评论(0)    

Keepalived双机热备

这里我们仅仅只利用Keepalive做双机热备,也就是保证服务器的高可用性,其他的不用管。可能您会说这样在实际应用中很少会这样用,这您可就错了,Keepalived仅仅做双机热备的情况还是有的,我就碰到过几次这样的案例,下面就我碰到的几个案例做个小结


一,Keepalived双机热备的应用场景


1,网站流量不高,压力不大,但是对服务器的可靠性要求极其高,例如实时在线OA系统,政府部门网站系统,医院实时报医系统,公安局在线报案系统,股市后台网站系统等等,他们的压力不是很大,但是对可靠性要求是非常高的


2,有钱没地方花的,典型的政府企业,公办学校等等


二,Keepalived双机热备的特性以及优缺点


特性:

1,至少需要两台服务器,其中一台为master始终提供服务,另外一台作为backup始终处于空闲状态,只有在主服务器挂掉的时候他就来帮忙了,这是典型的双击热备


2,能根据需求判断服务是否可用,在不可用的时候要即使切换

优缺点:


优点:数据同步非常简单,不像负载均衡对数据一致性要求非常高,实现起来相对复杂维护也颇为不便,双机热备用rsync就可以实现了操作和维护非常简单


缺点:服务器有点浪费,始终有一台处于空闲状态



三,Keepalived双机热备的配置
首先画个双机热备拓扑图吧:



这里我只写最终实现的配置,至于Keepalived的理论知识请参考《Keepalived原理与实战精讲

1,本例通过Keepalived来实现两台LNMP(也就是linux+nginx+mysql+php)架构服务器的双机热备

LNMP的配置请参考:《Lnmp配置精讲第一版

2,Keepalived配置双机安装配置

1》Keepalived安装

keepalived官方地址:http://www.keepalived.org/download.html,大家可以到这里下载最新版本的keepalived

操作系统:centos 5.5 32bit
系统安装:最小化安装,也就是去掉所有组件
环境配置:安装make 和 gcc openssl openssl-devel等等

  1. yum -y install gcc make openssl openssl-devel wget kernel-devel

  2. mkdir -p /usr/local/src/hasoft

  3. cd /usr/local/src/hasoft

  4. wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz

  5. tar -zxvf keepalived-1.2.2.tar.gz

  6. cd keepalived-1.2.2

  7. ./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.18-238.19.1.el5-i686/

复制代码

预编译后出现:

  1. Keepalived configuration

  2. ------------------------

  3. Keepalived version       : 1.2.2

  4. Compiler                 : gcc

  5. Compiler flags           : -g -O2 -DETHERTYPE_IPV6=0x86dd

  6. Extra Lib                : -lpopt -lssl -lcrypto

  7. Use IPVS Framework       : Yes

  8. IPVS sync daemon support : Yes

  9. IPVS use libnl           : No

  10. Use VRRP Framework       : Yes

  11. Use Debug flags          : No

复制代码
  1. make && make install

复制代码

这里注意哦,我上面是指通用的安装方法,如果你没有用到LVS可以把lvs去掉即
./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.18-238.19.1.el5-i686/ --disable-lvs-syncd --disable-lvs

但这个没有影响,就按照我的来配置吧,不过如果你要是集成了LVS,那么就不可加这两个参数了哦

整理管理文件:
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/


建立配置文件目录(注意:keepalived的配置文件默认在/etc/keepalived/目录)
mkdir -p /etc/etc/keepalived/

两台服务器(两个节点)都这样安装即可

2》配置

节点A配置如下:
vi /etc/keepalived/keepalived.conf

  1. global_defs

  2. {

  3. notification_email

  4. {

  5. admin@example.com

  6. admin@ywlm.net

  7. }

  8. notification_email_from admin@example.com

  9. smtp_server 127.0.0.1

  10. stmp_connect_timeout 30

  11. router_id lnmp_node1

  12. }


  13. vrrp_instance lnmp {

  14. state MASTER

  15. interface eth0

  16. virtual_router_id 100

  17. priority 200

  18. advert_int 5

  19. track_interface {

  20. eth0

  21. eth1

  22. }

  23. authentication {

  24. auth_type PASS

  25. auth_pass 123456

  26. }

  27. virtual_ipaddress {

  28. 192.168.17.200

  29. }

  30. }

复制代码


节点B配置如下:
vi /etc/keepalived/keepalived.conf

  1. global_defs

  2. {

  3. notification_email

  4. {

  5. admin@example.com

  6. admin@ywlm.net

  7. }

  8. notification_email_from admin@example.com

  9. smtp_server 127.0.0.1

  10. stmp_connect_timeout 30

  11. router_id lnmp_node1

  12. }


  13. vrrp_instance lnmp {

  14. state MASTER

  15. interface eth0

  16. virtual_router_id 100

  17. priority 150

  18. advert_int 5

  19. track_interface {

  20. eth0

  21. eth1

  22. }

  23. authentication {

  24. auth_type PASS

  25. auth_pass 123456

  26. }

  27. virtual_ipaddress {

  28. 192.168.17.200

  29. }

  30. }

复制代码

四,启动调试
在节点A上启动
/usr/local/keepalived/sbin/keepalived

启动日志:
Sep  8 18:26:02 centosa Keepalived_vrrp: Registering Kernel netlink reflector
Sep  8 18:26:02 centosa Keepalived_vrrp: Registering Kernel netlink command channel
Sep  8 18:26:02 centosa Keepalived_vrrp: Registering gratutious ARP shared channel
Sep  8 18:26:02 centosa Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:26:02 centosa Keepalived_vrrp: Configuration is using : 36076 Bytes
Sep  8 18:26:02 centosa Keepalived_vrrp: Using LinkWatch kernel netlink reflector...
Sep  8 18:26:02 centosa Keepalived: Starting VRRP child process, pid=5606
Sep  8 18:26:07 centosa Keepalived_vrrp: VRRP_Instance(lnmp) Transition to MASTER STATE
Sep  8 18:26:12 centosa Keepalived_vrrp: VRRP_Instance(lnmp) Entering MASTER STATE
Sep  8 18:26:12 centosa avahi-daemon[2528]: Registering new address record for 192.168.17.200 on eth0.


在节点B上启动
/usr/local/keepalived/sbin/keepalived

开机自动启动
echo /usr/local/keepalived/sbin/keepalived >> /etc/rc.local

启动日志:
Sep  8 18:30:02 centosb Keepalived: Starting Keepalived v1.2.2 (09/08,2011)
Sep  8 18:30:02 centosb Keepalived: Starting Healthcheck child process, pid=5837
Sep  8 18:30:02 centosb Keepalived_vrrp: Registering Kernel netlink reflector
Sep  8 18:30:02 centosb Keepalived_vrrp: Registering Kernel netlink command channel
Sep  8 18:30:02 centosb Keepalived_vrrp: Registering gratutious ARP shared channel
Sep  8 18:30:02 centosb Keepalived: Starting VRRP child process, pid=5839
Sep  8 18:30:02 centosb kernel: IPVS: Registered protocols (TCP, UDP, AH, ESP)
Sep  8 18:30:02 centosb kernel: IPVS: Connection hash table configured (size=4096, memory=32Kbytes)
Sep  8 18:30:02 centosb kernel: IPVS: ipvs loaded.
Sep  8 18:30:02 centosb Keepalived_healthcheckers: Registering Kernel netlink reflector
Sep  8 18:30:02 centosb Keepalived_healthcheckers: Registering Kernel netlink command channel
Sep  8 18:30:02 centosb Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:30:02 centosb Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Sep  8 18:30:02 centosb Keepalived_vrrp: Configuration is using : 36252 Bytes
Sep  8 18:30:02 centosb Keepalived_vrrp: Using LinkWatch kernel netlink reflector...
Sep  8 18:30:02 centosb Keepalived_healthcheckers: Configuration is using : 6271 Bytes
Sep  8 18:30:02 centosb Keepalived_healthcheckers: Using LinkWatch kernel netlink reflector...
Sep  8 18:30:02 centosb Keepalived_vrrp: VRRP_Instance(lnmp) Entering BACKUP STATE

从日志可以看出,启动都没有问题,并且安装我给的优先级完成了竞选,各自成就了各自的状态

关闭节点A的网卡测试切换是否正常
ifdown eth0

观察节点B的日志:
Sep  8 18:32:55 centosb Keepalived_vrrp: VRRP_Instance(lnmp) Transition to MASTER STATE
Sep  8 18:33:00 centosb Keepalived_vrrp: VRRP_Instance(lnmp) Entering MASTER STATE
Sep  8 18:33:00 centosb avahi-daemon[2531]: Registering new address record for 192.168.17.200 on eth0.


启动节点A的网卡测试切换是否正常
ifup eth0
观察节点B的日志:
Sep  8 18:33:31 centosb Keepalived_vrrp: VRRP_Instance(lnmp) Received higher prio advert
Sep  8 18:33:31 centosb Keepalived_vrrp: VRRP_Instance(lnmp) Entering BACKUP STATE
Sep  8 18:33:31 centosb avahi-daemon[2531]: Withdrawing address record for 192.168.17.200 on eth0.

Received higher prio advert:表示接收到更高优先级的公告(advert公告的意思)
Withdrawing:撤回的意思,可以看出切换过程一目了然


OK,到这里我们的安装部分完成,下面我们来看看如何监控服务吧,我们这里仅仅是监控了网络故障和keepalived本身进程,在网络或者keepalived进程出现问题的时候会切换,但是我的节点A里面还有很多服务呢,例如nginx,PHP,mysql进程出问题或高负载的时候相应过慢怎么办,怎么切换的呢,这时就要用到脚本了,下面我们来看看keepalived是如何控制脚本来实现对服务器的监控和切换的

写个脚本来实时监控三个服务,若有一个出现问题遍切换mkdir /root/shell/
cd /root/shell
vi keepcheck.sh

  1. #!/bin/bash

  2. while  :

  3. do

  4. mysqlcheck=`/usr/local/lnmp/mysql/bin/mysqladmin -uroot ping 2>&1`

  5. mysqlcode=`echo $?`

  6. phpcheck=`ps -C php-fpm --no-header | wc -l`

  7. nginxcheck=`ps -C nginx --no-header | wc -l`

  8. keepalivedcheck=`ps -C keepalived --no-header | wc -l`

  9. if [ $nginxcheck -eq 0 ]|| [ $phpcheck -eq 0 ]||[ $mysqlcode -ne 0 ];then

  10.                 if [ $keepalivedcheck -ne 0 ];then

  11.                    killall -TERM keepalived

  12.                 else

  13.                    echo "keepalived is stoped"

  14.                 fi

  15.         else

  16.                 if [ $keepalivedcheck -eq 0 ];then

  17.                    /etc/init.d/keepalived start

  18.                 else

  19.                    echo "keepalived is running"

  20.                 fi

  21. fi

  22. sleep 5

  23. done


复制代码

注意,用/etc/init.d/keepalived start如果起不来,可以用/usr/local/keepalived/sbin/keepalived二进制文件直接执行启动即可
启动脚本:

  1. chmod +x /root/shell/keepcheck.sh

  2. nohup sh /root/shell/keepcheck.sh &

复制代码

节点B也用这个脚本

写入/etc/rc.local开机自动启动

  1. echo "nohup sh /root/shell/keepcheck.sh &" >> /etc/rc.loal

复制代码

可以测试了

本文就写完了,这个可以用于生产环境,本人环境就这样配置的,但不同业务有不同环境,一定要按需调整,不要盲目盲从!


除非注明,发表在“Jiaozn的博客”的文章『【双机】Keepalived双机热备(HA)』版权归Jiaozn所有。 转载请注明出处为“本文转载于『Jiaozn的博客』原地址https://www.jiaozn.com/reed/147.html
0

评论

发表评论   

昵称*

E-mail*(建议输入,以便收到博主回复的提示邮件)

网站

分享:

支付宝

微信