preface
公司要求http+mysql+redis+二次开发的ldap要求做高可用，所以此处写写keepalived在这种
环境下的高可用。keepalived这个软件我就不啰嗦了，众所周知，基于VRRP协议做的高可用，VRRP就是virtual route protocol。把这个协议了解透了，keepalived自然也就明白怎么回事了。
实践
环境如下
| ip | 角色 |
|---|---|
| 172.16.160.189 | master |
| 172.16.160.179 | backup |
两台服务器都安装好了http,mysql,redis,以及ldap，确保两台服务器的http，mysql，redis以及ldap服务正常运行。
接下来重点讲解keepalived的配置文件
master 上配置keepalived
配置文件如下：
[root@localhost script]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
router_id LVS_DEVEL
}
vrrp_script monitor_server { # monitor_server是自定义名字
script "/etc/keepalived/script/check_server.sh" # 设定的脚本，脚本内容下面会贴出来
interval 1 #探测间隔，实际也是脚本的执行间隔
weight 0 # 权重，脚本执行后的返回值会与这个做加减法，然后再把值与下面vrrp_instance的权重值做加减。
}
vrrp_instance VI_1 {
state MASTER
interface eth0
lvs_sync_daemon_inteface eth0
virtual_router_id 51 # 与备份机的id值必须一样的。
priority 100 # 权重值
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.16.160.250
}
track_script {
monitor_server # 调用脚本模块
}
}
virtual_server 172.16.160.250 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol http # 因为这里要访问http协议，所以protocol写成http，这样浏览器才能访问，不然写成TCP的话，浏览器没法访问。
# real_server 172.16.160.179 80 {
# weight 100
# HTTP_CHECK {
# connect_timeout 2 #(10秒无响应超时)
# nb_get_retry 1
# delay_before_retry 1
# connect_port 80
# }
# }
# real_server 172.16.160.189 80 {
# weight 100
# HTTP_CHECK {
# connect_timeout 2 #(10秒无响应超时)
# nb_get_retry 1
# delay_before_retry 1
# connect_port 80
# }
# }
}
backup上的配置
[root@localhost keepalived]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
router_id LVS_DEVEL1 # 本机id
}
vrrp_script monitor_server{
script "/etc/keepalived/script/check_server.sh" # 同上
interval 1
weight 0
}
vrrp_instance VI_1 {
state BACKUP #角色改为ｂａｃｋｕｐ
interface eth0
lvs_sync_daemon_inteface eth0
virtual_router_id 51
priority 90 # 权重值调小即可
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.16.160.250
}
track_script {
monitor_server
}
}
virtual_server 172.16.160.250 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol HTTP
# real_server 172.16.160.179 80 {
# weight 100
# TCP_CHECK {
# connect_timeout 2 #(10秒无响应超时)
# nb_get_retry 1
# delay_before_retry 1
# connect_port 80
# }
# }
# real_server 172.16.160.189 80 {
# weight 100
# TCP_CHECK {
# connect_timeout 2 #(10秒无响应超时)
# nb_get_retry 1
# delay_before_retry 1
# connect_port 80
# }
# }
}
脚本内容
脚本编写思路很简单，检测每个服务是否在，如果不在，尝试脚本启动，启动不了的话，停止keepalived，这样vip就切换走了。
function judge_ge_1 {
if [ "$1" -ge "1" ];then
export result="true"
else
export result="false"
fi
}
function stop_keepalived {
if [ "$1" == "false" ];then
service keepalived stop
fi
}
################# check redis
exist_port=`netstat -lnpt |grep -v grep | grep 6379 |wc -l`
judge_ge_1 $exist_port
if [ "$result" == "false" ];then
/etc/init.d/redis start
fi
exist_port=`netstat -lnpt |grep -v grep | grep 6379 |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result
###################### check mysql
exist_port=`netstat -lnpt |grep -v greo | grep 3306 |wc -l`
judge_ge_1 $exist_port
if [ "$result" == "false" ];then
service mysqld restart
fi
exist_port=`netstat -lnpt |grep -v greo | grep 3306 |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result
################### check http
exist_port=`netstat -lnpt |grep -v grep | grep httpd |wc -l`
judge_ge_1 $exist_port
if [ "$result" == "false" ];then
service httpd restart
fi
exist_port=`netstat -lnpt |grep -v grep | grep httpd |wc -l`
judge_ge_1 $exist_port
stop_keepalived $result
[root@localhost script]# chmod 777 /etc/keepalived/script/check_server.sh # 最后不要忘记添加777的权限，保证具有可执行权限
有问题请随时与我联系，18500777133@sina.cn