# Keepalived

## 0、准备工作

准备三台主机，比如如下

```
A主机：192.168.1.10
B主机：192.168.1.11 
C主机：192.168.1.12
```

准备一个vip，注意不要被其他主机占用，而且要与上面三个IP在同一子网内，比如为

```
192.168.1.20
```

## 1、安装

在三台主机上都安装keepalived，执行以下命令即可安装

```
sudo yum -y install keepalived
```

## 2、配置文件

keepalived有两个配置文件，一个是/etc/sysconfig/keepalived，一个是/etc/keepalived/keepalived.conf

* /etc/sysconfig/keepalived

该文件中的有效内容只有一行，三个节点上这个文件的内容一样。为

```
KEEPALIVED_OPTIONS="-D"
```

* /etc/keepalived/keepalived.conf

这个文件在三台主机上的配置会不一样

> A主机

```
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_instance VI_1 {
    state MASTER        # B C 主机设为BACKUP
    interface eth0      # IP对应的网卡
    virtual_router_id 20    # 三台主机这个id要一致，如果局域网内还有其他的vip，注意这个值要与其他vip不同
    priority 100    # MASTER设100，BACKUP设99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.20    # vip
    }
}
```

> B C主机相同，如下

```
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_instance VI_1 {
    state BACKUP        # B C 主机设为BACKUP
    interface eth0      # IP对应的网卡
    virtual_router_id 20    # 三台主机这个id要一致
    priority 99    # MASTER设100，BACKUP设99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.20    # vip
    }
}
```

## 3、unit文件

* /usr/lib/systemd/system/keepalived.service

三台主机的内容一样，如下：

```
[Unit]
Description=LVS and VRRP High Availability Monitor
After=syslog.target network.target

[Service]
Type=forking
KillMode=process
EnvironmentFile=-/etc/sysconfig/keepalived
ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target
```

4、将keepalived设置为开机启动

```
sudo systemctl enable keepalived
```