linux之keepalived详解

标签：双机热备

一、keepalive简介

     Keepalived是专门针对LVS设计的一款强大的辅助工具，主要用来提供故障切换和健检查功能，如判断LVS负载调度器、节点服务器的可用性，及时隔离并替换为新的服务器，当故障主机恢复后将其重新加入群集。在非LVS群集环境中使用时Keepalived也可以作为热备软件使用。

Keepalived采用VRRP(virtual  router  redundancy protocol，虚拟路由冗余协议)热备份协议，以软件的方式实现linux服务器的多机热备功能。VRRP是针对路由器的一种备份解决方案-----由多台路由器组成一个热备组。通过共用的虚拟IP地址对外提供服务；每个热备组内同一时刻只有一台主服务器提供服务，其他服务器处于冗余状态，若当前在线的服务器失败，其他服务器会自动接替（优先级决定接替顺序）虚拟IP地址，以继续提供服务。

热备组内的每台服务器都可以成为主服务器，虚拟IP地址（VIP）可以在热备组内的服务器之间进行转移，所以也称为漂移IP地址，使用Keepalived时，漂移地址的实现不需要手动建立虚拟接口配置文件（如eth0:0），而是由Keepalived根据配置文件自动管理。

二、keepalive原理

keepalived启动后会有三个进程
父进程：内存管理，子进程管理等等
子进程：VRRP子进程
子进程：healthchecker子进程

有图可知，两个子进程都被系统WatchDog看管，两个子进程各自复杂自己的事，healthchecker子进程复杂检查各自服务器的健康程度，例如HTTP，LVS等等，如果healthchecker子进程检查到MASTER上服务不可用了，就会通知本机上的兄弟VRRP子进程，让他删除通告，并且去掉虚拟IP，转换为BACKUP状态。

三、部署keepalived服务

环境：Centos6.5-x64位系统

IP:172.16.16.15(master),172.16.16.16(backup)

VIP:172.16.16.100

关闭iptables，selinux

只是演示keepalive的常用配置，因此yum安装，如有需要，请百度源码安装。

[root@localhost ~]# yum install keepalived -y

keepalive主配置文件在/etc/keepalived/下，

1.实现简单的VIP漂移

master配置文件：

! Configuration File for keepalived

global_defs {

   notification_email {

    root@localhost   ##########收件人邮箱，每行一个收件人

   }

   notification_email_from keepadmin@localhost   #########发件人邮箱，可以不存在

   smtp_server 127.0.0.1       ###########邮件服务器地址

   smtp_connect_timeout 30     ########邮件服务器连接超时时间

   router_id LVS_DEVEL       #########服务器的标识

}

vrrp_instance VI_1 {        ########热备实例

    state MASTER         ########热备状态

    interface eth0       #########监控心跳，向备发送宣告

    virtual_router_id 51   #########虚拟路由id，主备必须一致

    priority 100        #########定义优先级，值越大优先级越高

    advert_int 1       #########主备宣告的时间间隔，

    authentication {    #########设置验证

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        172.16.16.100   ######定义vip，注此机器只有一块网卡，默认加到eth0上，若多块网卡，或者子卡，可以设置为172.16.16.100 dev eth1[label eth0:0]等指定设备

    }

}

backup配置文件：

! Configuration File for keepalived

global_defs {

   notification_email {

     root@localhost

   }

   notification_email_from keepadmin@localhost

   smtp_server 127.0.0.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state BACKUP          ###修改此节点为备

    interface eth0

    virtual_router_id 51

    priority 99         ########优先级要比主低

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        172.16.16.100

    }

}

启动两个几点keepalived

master：

root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

    inet 172.16.16.100/32 scope global eth0

    inet6 fe80::20c:29ff:fec2:ccff/64 scope link 

       valid_lft forever preferred_lft forever

backup

[root@localhost keepalived]# ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

    inet6 fe80::20c:29ff:fe5c:ef24/64 scope link 

       valid_lft forever preferred_lft forever

关闭master的keepalive,

master

[root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

    inet6 fe80::20c:29ff:fec2:ccff/64 scope link 

       valid_lft forever preferred_lft forever

backup

[root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

    inet 172.16.16.100/32 scope global eth0   #######vip漂移到backup

    inet6 fe80::20c:29ff:fe5c:ef24/64 scope link 

       valid_lft forever preferred_lft forever

2.定义简单的脚本命令

在/etc/keepalived/目录下，检测到down文件，vip漂移

master/backup

global_defs {

   notification_email {

     root@localhost

   }

   notification_email_from keepadmin@localhost

   smtp_server 127.0.0.1

! Configuration File for keepalived

global_defs {

   notification_email {

     root@localhost

   }

   notification_email_from keepadmin@localhost

   smtp_server 127.0.0.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_script chk_maintainace {      #######定义检测脚本参数vrrp_script，chk_maintainace自定义

   script "[[  -f /etc/keepalived/down ]] && exit 1 || exit 0" ##可以为脚本，或命令

   interval 1  ######检测down文件的时间间隔为1秒

   weight -2   ########检测到down文件，优先级-2（即100-2）

}

vrrp_instance VI_1 {

    state MASTER/BACKUP

    interface eth0

    virtual_router_id 51

    priority 100/99

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        172.16.16.100

    }

    track_script {                                 

    chk_maintainace   ############追踪脚本

    }

}

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

    inet 172.16.16.100/32 scope global eth0

    inet6 fe80::20c:29ff:fec2:ccff/64 scope link 

       valid_lft forever preferred_lft forever

[root@localhost keepalived]# touch down

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

    inet6 fe80::20c:29ff:fec2:ccff/64 scope link   ######vip漂移

       valid_lft forever preferred_lft forever

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

    inet 172.16.16.100/32 scope global eth0 ######vip漂移到backup

    inet6 fe80::20c:29ff:fe5c:ef24/64 scope link 

       valid_lft forever preferred_lft forever

[root@localhost keepalived]# rm -rf down 主删除down

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

    inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

    inet 172.16.16.100/32 scope global eth0  ######vip漂移回master

    inet6 fe80::20c:29ff:fec2:ccff/64 scope link 

       valid_lft forever preferred_lft forever

linux之keepalived详解

标签：双机热备

原文地址：http://weilantiankong.blog.51cto.com/9469693/1761809