Keepalived实现了一套VRRP协议(虚拟路由协议)，这个协议允许服务器可以动态的设置IP路由。 使用Keepalived可以加强负载均衡软件的可用性。

环境信息

1192.168.61.3 ha1 - MASTER
2192.168.61.4 ha2 - BACKUP

Keepalived编译安装

1yum -y install openssl-devel
2
3wget http://www.keepalived.org/software/keepalived-<version>.tar.gz
4tar -zxvf keepalived-<version>.tar.gz
5cd keepalived-<version>
6./configure --prefix=/usr/local/keepalived
7
8make
9make install

安装psmisc

安装psmisc，可使用 killall -0 haproxy检查haproxy实例是否存活，性能高于ps。

1yum install -y psmisc

配置

编辑配置文件/usr/local/keepalived/etc/keepalived/keepalived.conf：

 1! Configuration File for keepalived
 2
 3global_defs {
 4   router_id LVS_DEVEL
 5}
 6
 7vrrp_script chk_haproxy {
 8    script "/usr/bin/killall -0 haproxy"
 9    interval 2
10    weight 2
11}
12
13vrrp_instance VI_1 {
14    state MASTER
15    interface eth0
16    virtual_router_id 51
17    priority 100
18    advert_int 1
19    virtual_ipaddress {
20        192.168.61.2
21    }
22    track_script {
23      chk_haproxy
24    }
25}

配置文件关键配置如下：

  • vrrp_script chk_haproxy Haproxy健康检查
  • script "/usr/bin/killall -0 haproxy" 检查haproxy是否存活
  • interval 2 脚本运行周期
  • weight 2 每次检查加权权重
  • vrrp_instance VI_1 虚拟路由配置
  • state MASTER 本机实例状态，备机配置文件中填写BACKUP
  • interface eth0 本机网卡名称
  • virtual_router_id 虚拟路由编号，主机和备机要保持一致
  • priority 100 本机初始权重，备机填写小雨主机的权重值
  • advert_int 争抢虚拟地址的周期，单位秒
  • virtual_ipaddress 虚拟IP地址，主备机保持一致
  • track_script 对应的健康检查

启动keepalived

注册为系统服务/usr/lib/systemd/system/keepalived.service：

 1[Unit]
 2Description=LVS and VRRP High Availability Monitor
 3After=syslog.target network-online.target
 4
 5[Service]
 6Type=simple
 7PIDFile=/var/run/keepalived.pid
 8KillMode=process
 9EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
10ExecStart=/usr/local/keepalived/sbin/keepalived -f /usr/local/keepalived/etc/keepalived/keepalived.conf $KEEPALIVED_OPTIONS
11ExecReload=/bin/kill -HUP $MAINPID
12
13[Install]
14WantedBy=multi-user.target

接下来启动keepalived：

1systemctl enable keepalived
2systemctl start keepalived

测试

在ha1上查看网卡eth0

1ip addr sh eth0
22: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
3    link/ether 08:00:27:68:cc:c1 brd ff:ff:ff:ff:ff:ff
4    inet 192.168.61.3/24 brd 192.168.61.255 scope global enp0s8
5       valid_lft forever preferred_lft forever
6    inet 192.168.61.2/32 scope global enp0s8
7       valid_lft forever preferred_lft forever
8    inet6 fe80::a00:27ff:fe68:ccc1/64 scope link
9       valid_lft forever preferred_lft forever

可以看到目前虚IP被ha1持有。

在ha2上查看：

1ip addr sh eth0
22: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
3    link/ether 08:00:27:68:cc:c1 brd ff:ff:ff:ff:ff:ff
4    inet 192.168.61.4/24 brd 192.168.61.255 scope global enp0s8
5       valid_lft forever preferred_lft forever
6    inet6 fe80::a00:27ff:fe68:ccc1/64 scope link tentative dadfailed
7       valid_lft forever preferred_lft forever

ha2没有持有虚IP。

通过虚IP测试haproxy服务：

1curl 192.168.61.2
2Hello

停止ha1上的haproxy，一会虚IP会漂移到ha2上。