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Keepalived

文章目录

高可用:两台业务系统启动着相同的服务,如果有一台故障,另一台自动接管,我们将将这个称之为高可用;

Keekpalived工作原理:通过vrrp协议实现

vrrp原理

vrrp抓包

Keepalived工作方式:抢占式、非抢占式

安装:yum install keepalived -y

日志存放位置:/var/log/messages

1、keepaliaved 抢占式配置

master配置

[root@lb01 ~]# rpm -qc keepalived
/etc/keepalived/keepalived.conf
/etc/sysconfig/keepalived
[root@lb01 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb02 #标识信息,一个名字而已;
}
vrrp_instance VI_1 {
    state MASTER    #角色是master
    interface eth0  #vip 绑定端口
    virtual_router_id 50    #让master 和backup在同一个虚拟路由里,id 号必须相同;
    priority 150            #优先级,谁的优先级高谁就是master ;
    advert_int 1            #心跳间隔时间
    authentication {
        auth_type PASS      #认证
        auth_pass 1111      #密码 
}
    virtual_ipaddress {
        10.0.0.3            #虚拟ip
    }
}

backup配置

[root@lb02 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {     
    router_id lb02   
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 50
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
}

[root@lb02 ~]# 

2、Keepalived非抢占式配置:

非抢占式不再有主从之分,全部都为BACKUP,并且配置文件中添加nopreempt,用来标识为非抢占式;

[root@lb01 /etc/nginx/upstream]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 50
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
}


[root@lb02 /etc/nginx/upstream]# cat /etc/keepalived/keepalived.conf 
! Configuration File for keepalived
global_defs {     
    router_id lb02   
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 50
    priority 100
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
}

You have new mail in /var/spool/mail/root
[root@lb02 /etc/nginx/upstream]# 

3、nginx+keepalived

实现思路:将keepalived 中的vip作为nginx负载均衡的监听地址,并且域名绑定的也是vip的地址。
说明:Nginx 负载均衡实现高可用,需要借助Keepalived地址漂移功能。

在不考虑后端数据库和存储的时候如下架构

keepalived+Nginx
两台负载均衡配置:

[root@lb01 /etc/nginx/upstream]# ip add show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:97:e1:ff brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.5/24 brd 10.0.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet 10.0.0.3/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe97:e1ff/64 scope link 
       valid_lft forever preferred_lft forever
[root@lb01 /etc/nginx/upstream]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 50
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
}


[root@lb01 /etc/nginx/upstream]# 

[root@lb02 /etc/nginx/upstream]# ip add show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:6f:18:48 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.6/24 brd 10.0.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe6f:1848/64 scope link 
       valid_lft forever preferred_lft forever
[root@lb02 /etc/nginx/upstream]# cat /etc/keepalived/keepalived.conf 
! Configuration File for keepalived
global_defs {     
    router_id lb02   
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 50
    priority 100
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
}

[root@lb02 /etc/nginx/upstream]# 

4、keepalived脑裂现象

由于某些原因,导致两台keepalived高可用服务器在指定时间内,无法检测到对方存活心跳信息,从而导致互相抢占对方的资源和服务所有权,然而此时两台高可用服务器有都还存活。
可能出现的原因:
1、服务器网线松动等网络故障;
2、服务器硬件故障发生损坏现象而崩溃;
3、主备都开启了firewalld 防火墙。
4、在Keepalived+nginx 架构中,当Nginx宕机,会导致用户请求失败,但是keepalived不会进行切换,
所以需要编写一个检测nginx的存活状态的脚本,如果nginx不存活,则kill掉宕掉的nginx主机上面的keepalived。(所有的keepalived都要配置)

架构如下:

image.png

脚本如下:

[root@lb01 /server/scripts]# cat /server/scripts/check_list 
#!/bin/sh

nginxpid=$(ps -C nginx --no-header|wc -l)
#1.判断Nginx是否存活,如果不存活则尝试启动Nginx
if [ $nginxpid -eq 0 ];then
    systemctl start nginx
    sleep 3
    #2.等待3秒后再次获取一次Nginx状态
    nginxpid=$(ps -C nginx --no-header|wc -l) 
    #3.再次进行判断, 如Nginx还不存活则停止Keepalived,让地址进行漂移,并退出脚本  
    if [ $nginxpid -eq 0 ];then
        systemctl stop keepalived
   fi
fi
[root@lb01 /server/scripts]# 

配置文件如下:

[root@lb01 /server/scripts]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id lb01
}

vrrp_script check {
    script "/server/scripts/check_list"
    interval  10


}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 50
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
}
    virtual_ipaddress {
        10.0.0.3
    }
    track_script  {
    check
}
}
[root@lb01 /server/scripts]# 

历史上的今天
六月
17
    哇哦~~~,历史上的今天没发表过文章哦
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