keepalived高可用

Keepalived提供了很好的高可用性保障服务，它可以检查服务器的状态，如果有服务器出现问题，Keepalived会将其从系统中移除，当这台服务器可以正常工作后，
Keepalived再将其放入服务器群中，这个过程是Keepalived自动完成的，不需要人工干涉，我们只需要修复出现问题的服务器

高可用HA（High Availability）是分布式系统架构设计中必须考虑的因素之一，它通常是指，通过设计减少系统不能提供服务的时间

假设系统一直能够提供服务，我们说系统的可用性是100%

如果系统每运行100个时间单位，会有1个时间单位无法提供服务，我们说系统的可用性是99%

很多公司的高可用目标是4个9，也就是99.99%，这就意味着，系统的年停机时间为8.76个小时

通过vrrp协议实现,虚拟路由冗余协议

主服务器172.17.1.32
从服务器172.17.1.24

一、主服务器配置
1、查看网卡
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether c4:00:ad:20:93:e6 brd ff:ff:ff:ff:ff:ff
    inet 172.17.1.32/16 brd 172.17.255.255 scope global noprefixroute enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::f104:bae1:d237:4d35/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: enp4s15: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 08:57:00:f7:a4:64 brd ff:ff:ff:ff:ff:ff
[root@localhost ~]# 

2、安装
yum install-y keepalived 

3、查看配置文件位置
rpm -qc keepalived
[root@localhost ~]# rpm -qc keepalived
/etc/keepalived/keepalived.conf
/etc/sysconfig/keepalived
[root@localhost ~]# 

4、编写配置文件内容
global_defs {
router_id lb01
}

vrrp_instance oldboy {
    state MASTER
    interface enp2s0
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.17.1.34
    }
}
5、启动
systemctl start keepalived.service
systemctl stop keepalived.service
systemctl restart keepalived.service
开机自启动
systemctl enable keepalived

6、查看
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether c4:00:ad:20:93:e6 brd ff:ff:ff:ff:ff:ff
    inet 172.17.1.32/16 brd 172.17.255.255 scope global noprefixroute enp2s0
       valid_lft forever preferred_lft forever
    inet 172.17.1.34/32 scope global enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::f104:bae1:d237:4d35/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: enp4s15: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000

二、从服务器配置
1、查看网卡
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp7s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 40:b0:76:47:f1:39 brd ff:ff:ff:ff:ff:ff
3: enp4s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 2c:53:4a:09:e4:fa brd ff:ff:ff:ff:ff:ff
    inet 172.17.1.24/24 brd 172.17.1.255 scope global noprefixroute enp4s0f0
       valid_lft forever preferred_lft forever
    inet 172.17.1.34/32 scope global enp4s0f0
       valid_lft forever preferred_lft forever
    inet6 fe80::1903:e1e:a381:6790/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

2、安装
yum install-y keepalived 

3、查看配置文件位置
rpm -qc keepalived
[root@localhost ~]# rpm -qc keepalived
/etc/keepalived/keepalived.conf
/etc/sysconfig/keepalived
[root@localhost ~]# 

4、编写配置文件
global_defs {
router_id lb01
}

vrrp_instance oldboy {
    state BACKUP
    interface enp4s0f0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        172.17.1.34
    }
}
5、启动
systemctl start keepalived.service
systemctl stop keepalived.service
systemctl restart keepalived.service
开机自启动
systemctl enable keepalived

6、查看
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp7s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 40:b0:76:47:f1:39 brd ff:ff:ff:ff:ff:ff
3: enp4s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 2c:53:4a:09:e4:fa brd
    ff:ff:ff:ff:ff:ff
    inet 172.17.1.24/24 brd 172.17.1.255 scope global noprefixroute enp4s0f0
       valid_lft forever preferred_lft forever
    inet6 fe80::1903:e1e:a381:6790/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

三、测试
1、主服务器
systemctl stop keepalived.service
2、查看VIP是否漂移
查看主服务器
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether c4:00:ad:20:93:e6 brd ff:ff:ff:ff:ff:ff
    inet 172.17.1.32/16 brd 172.17.255.255 scope global noprefixroute enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::f104:bae1:d237:4d35/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: enp4s15: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
查看从服务器
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp7s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 40:b0:76:47:f1:39 brd ff:ff:ff:ff:ff:ff
3: enp4s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 2c:53:4a:09:e4:fa brd ff:ff:ff:ff:ff:ff
    inet 172.17.1.24/24 brd 172.17.1.255 scope global noprefixroute enp4s0f0
       valid_lft forever preferred_lft forever
    inet 172.17.1.34/32 scope global enp4s0f0
       valid_lft forever preferred_lft forever
    inet6 fe80::1903:e1e:a381:6790/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever