18.1 集群介绍;18.2 keepalived介绍;18.3-18.5用keepalived配置

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18.1 集群介绍

1. 根据功能划分为两大类:高可用负载均衡

2. 高可用集群通常为两台服务器,一台工作,另外一台作为冗余,当提供服务的机器宕机,冗余将接替继续提供服务

3. 实现高可用的开源软件有:heartbeatkeepalived

负载均衡集群,需要有一台服务器作为分发器,它负责把用户的请求分发给后端的服务器处理,在这个集群里,除了分发器外,就是给用户提供服务的服务器了,这些服务器数量至少为2

4. 实现负载均衡的开源软件有LVSkeepalivedhaproxynginx,商业的有F5Netscaler

18.2 keepalived介绍

1. 在这里我们使用keepalived来实现高可用集群,因为heartbeat在centos6上有一些问题,影响实验效果

2. keepalived通过VRRP(Virtual Router Redundancy Protocl)来实现高可用。

3. 在这个协议里会将多台功能相同的路由器组成一个小组,这个小组里会有1个master角色和N(N>=1)个backup角色。

4. master会通过组播的形式向各个backup发送VRRP协议的数据包,当backup收不到master发来的VRRP数据包时,就会认为master宕机了。此时就需要根据各个backup的优先级来决定谁成为新的mater。

5. Keepalived要有三个模块,分别是core、check和vrrp。其中core模块为keepalived的核心,负责主进程的启动、维护以及全局配置文件的加载和解析,check模块负责健康检查,vrrp模块是来实现VRRP协议的。

18.3-18.5用keepalived配置高可用集群(上中下)

1. 准备两台机器hao1hao2

hao1作为masterhao2作为backup

2. 两台机器都安装 :yum install -y keepalived

[[email protected] ~]# yum install -y keepalived

[[email protected] ~]# yum install -y keepalived

3. 两台机器都安装nginx,可以编译安装nginx

也可以用yum安装nginx : yum install -y nginx

安装epel仓库(源码包,默认centos不带nginx包) :

yum install -y epel-release

yum install -y nginx

yum安装nginx启动:service nginx start

编译安装nginx启动:/etc/init.d/nginx start

4. 搜索nginx是否启动 ?

[[email protected] ~]# ps aux |grep nginx

[[email protected] ~]# ps aux |grep nginx

hao1机器上操作

5. 清空keepalived.conf文件中的内容(hao1机器) :

[[email protected] ~]# > /etc/keepalived/keepalived.conf

6. 重新配置keepalived.conf文件(hao1机器) :

[[email protected] ~]# vim /etc/keepalived/keepalived.conf

插入内容:

global_defs {

 bal_defs {

  notification_email {

    [email protected]

  }

  notification_email_from [email protected]hao.com

  smtp_server 127.0.0.1

  smtp_connect_timeout 30

  router_id LVS_DEVEL

}

vrrp_script chk_nginx {

   script "/usr/local/sbin/check_ng.sh"

   interval 3

}

vrrp_instance VI_1 {

   state MASTER

   interface ens33

   virtual_router_id 51

   priority 100

   advert_int 1

   authentication {

       auth_type PASS

       auth_pass haomima>com

   }  

   virtual_ipaddress {

      192.168.223.100

   }  

   track_script {

       chk_nginx

   }  

}

技术分享图片技术分享图片

7. 创建check_ng.sh脚本,并添加内容 :

[[email protected] ~]# vim /usr/local/sbin/check_ng.sh

插入内容:

#!/bin/bash

#时间变量,用于记录日志

d=`date --date today +%Y%m%d_%H:%M:%S`

#计算nginx进程数量

n=`ps -C nginx --no-heading|wc -l`

#如果进程为0,则启动nginx,并且再次检测nginx进程数量,

#如果继续还是为0,说明nginx无法启动,此时需要关闭keepalived

if [ $n -eq "0" ]; then

       /etc/init.d/nginx start

#yum安装的nginx用:systemctl start nginx  编译安装的用:/etc/init.d/nginx start

       n2=`ps -C nginx --no-heading|wc -l`

       if [ $n2 -eq "0"  ]; then

               echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log

               systemctl stop keepalived

       fi

fi技术分享图片技术分享图片

8. 设定check_ng.sh脚本755权限

[[email protected] ~]# chmod 755 /usr/local/sbin/check_ng.sh

9. 启动keepalived

[[email protected] ~]# systemctl start keepalived

10. 搜索keepalived是否启动

[[email protected] ~]# ps aux |grep keepalived

技术分享图片

技术分享图片11. 临时关闭getenforce防火墙

[[email protected] ~]# setenforce 0

关闭firewalld防火墙

[[email protected] ~]# systemctl stop firewalld

hao2机器上操作

12. 清空keepalived.conf文件中的内容(hao2机器) :

[[email protected] ~]# > /etc/keepalived/keepalived.conf

13. 重新配置keepalived.conf文件(hao2机器) :

[[email protected] ~]# vim /etc/keepalived/keepalived.conf

global_defs {

  notification_email {

    [email protected]

  }

  notification_email_from [email protected]hao.com

  smtp_server 127.0.0.1

  smtp_connect_timeout 30

  router_id LVS_DEVEL

}

vrrp_script chk_nginx {

   script "/usr/local/sbin/check_ng.sh"

   interval 3

}

vrrp_instance VI_1 {

   state BACKUP

   interface ens33

   virtual_router_id 51

   priority 90

   advert_int 1

   authentication {

       auth_type PASS

       auth_pass haomima>com

   }

   virtual_ipaddress {

      192.168.223.100

   }

   track_script {

       chk_nginx

   }

}

14. 创建check_ng.sh脚本,并添加内容 :

[[email protected] ~]# vim /usr/local/sbin/check_ng.sh

#!/bin/bash

#时间变量,用于记录日志

d=`date --date today +%Y%m%d_%H:%M:%S`

#计算nginx进程数量

n=`ps -C nginx --no-heading|wc -l`

#如果进程为0,则启动nginx,并且再次检测nginx进程数量,

#如果继续还是为0,说明nginx无法启动,此时需要关闭keepalived

if [ $n -eq "0" ]; then

       systemctl start nginx

#yum安装的nginx用:systemctl start nginx  编译安装的用:/etc/init.d/nginx start

       n2=`ps -C nginx --no-heading|wc -l`

       if [ $n2 -eq "0"  ]; then

               echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log

               systemctl stop keepalived

       fi

fi

15. 设定check_ng.sh脚本755权限

[[email protected] ~]# chmod 755 /usr/local/sbin/check_ng.sh

16. 启动keepalived

[[email protected] ~]# systemctl start keepalived

17. 搜索keepalived是否启动

[[email protected] ~]# ps aux |grep keepalived

18. 临时关闭getenforce防火墙

[[email protected] ~]# setenforce 0

关闭firewalld防火墙

[[email protected] ~]# systemctl stop firewalld

hoa1 hao2机器都打开80端口:

打开80端口 :

[[email protected] ~]# iptables -I INPUT -p tcp --dport 80 -j ACCEPT

[[email protected] ~]# iptables -I INPUT -p tcp --dport 80 -j ACCEPT

游览器访问hao1 hao2 ip

技术分享图片

hao2

技术分享图片

测试高可用

1. 关闭Nginx,再搜索nginx是否启动

[[email protected] ~]# systemctl stop nginx

[[email protected] ~]# ps aux |grep nginx

技术分享图片技术分享图片

2. ip add查看.100是不是在hao1机器上(master) :

[[email protected] ~]# ip add

技术分享图片

模仿hao1机器挂了,关闭了 keepalived

[[email protected] ~]# systemctl stop keepalived

[[email protected] ~]# ip add

技术分享图片

3. hao1机器(master)挂了,hao2机器(backup)上,ip add查看.100自动挂载到了hao2上!

技术分享图片

4. hao1机器(master)再启动keepalived .100又挂在hao1机器 :

[[email protected] ~]# systemctl start keepalived

技术分享图片


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