2019-03-27笔记—用keepalived搭建高可用集群

涉及理论知识点：VRRP协议 https://blog.csdn.net/zhyvodka/article/details/41800399

实验环境准备：

三台机器恢复快照，抹掉LVS的实验痕迹
linux2019_01（85.129）：web1
linux2019_02（85.128）：Nginx负载均衡1
linux2019_03（85.130）：Nginx负载均衡2，同时也是web2

实验步骤：

在两台负载均衡机器上安装nginx服务

[root@linux2019_02 ~]# vi /etc/yum.repos.d/nginx.repo
[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/7/$basearch/
gpgcheck=0
enabled=1
[root@linux2019_02 ~]# yum install -y nginx
[root@linux2019_02 ~]# vim /etc/nginx/conf.d/bbs_proxy.conf  配置负载均衡
upstream bbs 
{
	server 192.168.222.129:443; 
	server 192.168.222.130:443;
}
server
{
	listen 80;
	server_name bbs.aibenwoniu.xyz;
	location /
	{
	    proxy_pass http://bbs;
	    proxy_set_header Host $host;
	    proxy_set_header X-Real-IP $remote_addr;
	    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	}
}
[root@linux2019_02 ~]# systemctl start nginx

另一台nginx负载均衡机器上安装部署nginx服务

[root@linux2019_03 ~]# vi /etc/yum.repos.d/nginx.repo
[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/7/$basearch/
gpgcheck=0
enabled=1
[root@linux2019_03 ~]# yum install -y nginx
[root@linux2019_03 ~]# vim /etc/nginx/conf.d/bbs_proxy.conf  配置负载均衡
upstream bbs 
{
	server 192.168.222.129:443; 
	server 192.168.222.130:443;
}
server
{
	listen 80;
	server_name bbs.aibenwoniu.xyz;
	location /
	{
	    proxy_pass http://bbs;
	    proxy_set_header Host $host;
	    proxy_set_header X-Real-IP $remote_addr;
	    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	}
}
[root@linux2019_02 ~]# systemctl start nginx

补充：关于upstream配置 https://blog.csdn.net/zwhfyy/article/details/70856035

在两台nginx负载均衡机器上部署keepalived

[root@linux2019_02 ~]# yum install -y keepalived
[root@linux2019_02 ~]# vim /etc/keepalived/keepalived.conf 
global_defs {
    notification_email {
    [email protected] #定义接收邮件人
}
notification_email_from #定义发邮件地址（实际没有）
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id 001
}

vrrp_script chk_nginx {
    script "/usr/local/sbin/check_ng.sh" //此脚本为监控nginx服务的
    interval 3
}

vrrp_instance linux2019_02 {
    state MASTER
    interface ens33 //网卡
    virtual_router_id 001
    priority 100 //权重100，此数值要大于backup
    advert_int 1
    authentication {
	auth_type PASS
	auth_pass root //定义密码
    }
    virtual_ipaddress {
	192.168.85.100 //定义VIP
    }

    track_script {
	chk_nginx //定义监控脚本，这里和上面vrr_script后面的字符串保持一致
    }
}

另一台nginx负载均衡机器上安装部署keepalived

[root@linux2019_03 ~]# yum install -y keepalived
[root@linux2019_03 ~]# vim /etc/keepalived/keepalived.conf 
global_defs {
    notification_email {
    [email protected] #定义接收邮件人
}
notification_email_from #定义发邮件地址（实际没有）
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id 001
}

vrrp_script chk_nginx {
    script "/usr/local/sbin/check_ng.sh" //此脚本为监控nginx服务的
    interval 3
}

vrrp_instance linux2019 {
    state BACKUP
    interface ens33 //网卡
    virtual_router_id 001
    priority 90 //权重90，此数值要效于master
    advert_int 1
    authentication {
	auth_type PASS
	auth_pass root //定义密码
    }
    virtual_ipaddress {
	192.168.85.100 //定义VIP
    }

    track_script {
	chk_nginx //定义监控脚本，这里和上面vrr_script后面的字符串保持一致
    }
}

补充： keepalived中如何配置第三方邮件告警 https://blog.csdn.net/HzSunshine/article/details/62052398

两台高可用机器上编写nginx监控脚本

[root@linux2019_02 ~]# vim /usr/local/sbin/check_ng.sh 
#!/bin/bash#时间变量，用于记录日志
d=`date +%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，#如果还为0，说明nginx无法启动，此时需要关闭keepalived
if [ $n -eq 0 ]
then
    systemctl start nginx  #启动命令
    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
[root@linux2019_02 ~]# chmod 755 /usr/local/sbin/check_ng.sh
[root@linux2019_02 ~]# systemctl start keepalived

防火墙问题：保证VRRP协议放行，SElinux要关闭

iptables -A INPUT -p vrrp -j ACCEPT
setenforce 0

测试

在主服务器上停止nginx服务，因为有nginx监测脚本，会立刻自动恢复nginx服务；
在主服务器上错误修改nginx配置，导致nginx服务不可用，keepalived会立刻切换到备用nginx负载均衡机器上，由BACKUP变更为MASTER

2019-03-27笔记—用keepalived搭建高可用集群

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