1. Highly reliable concept
HA (High Available), high availability cluster is a valid business continuity solutions, generally have two or more nodes, and into the active node and the backup node.
2. Highly reliable software keepalived
keepalive is a software that can achieve high reliability, usually deployed in 2 on the server, is divided into a main one. Keepalived may be made to the detection processes on the machine, once the Master detects a problem with the process, will switch themselves into Backup state, then switched to another node notifies Master state.
3.keepalived installation
Download keepalived official website : http: //keepalived.org
The keepalived extract to / usr / local / src directory
tar -zxvf keepalived-1.2.19.tar.gz -C /usr/local/src
Into /usr/local/src/keepalived-1.2.19 directory
cd /usr/local/src/keepalived-1.2.19
Began to configure
./configure --prefix=/usr/local/keepalived
# Compile and install
make && make install
4. keepalived services added to the system (which can be started with the service command) in
Copy the executable file
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
The init.d files are copied to etc under , adding boot entry
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
Keepalived will copy the file to the etc under
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
Creating keepalived folder
mkdir -p /etc/keepalived
The keepalived copy the configuration file to etc under
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
Add executable permissions
chmod +x /etc/init.d/keepalived
## All of the above one-time command execution:
| cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ mkdir -p /etc/keepalived cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf chmod +x /etc/init.d/keepalived chkconfig --add keepalived chkconfig keepalived on |
Add keepalived to boot automatically activated
chkconfig --add keepalived
chkconfig keepalived on
5. Configure virtual IP keepalived
Modify the configuration file: /etc/keepalived/keepalived.conf
#MASTER node
| global_defs { } vrrp_instance VI_1 { state MASTER # Specify A is provided on the spare node to node is a primary node BACKUP to interface eth0 # Bind virtual IP network interface #VRRP virtual_router_id 51 disposed group name must be the same two nodes to indicate that each node belonging to the same VRRP group priority 100 # priority (master node 1-254 between), the node must be lower than the standby node priority advert_int 1 # multicast transmission interval ( heartbeat detection interval ) , the same two nodes must be provided authentication {# provided authentication information, both nodes must agree auth_type PASS auth_pass 1111 } virtual_ipaddress { #指定虚拟IP(用户可见的ip地址), 两个节点设置必须一样 192.168.33.60/24 #如果两个nginx的ip分别是192.168.33.61,,...62，则此处的虚拟ip跟它俩同一个网段即可 } } |
#BACKUP节点
| global_defs { } vrrp_instance VI_1 { state BACKUP # 备用节点 interface eth0 virtual_router_id 51 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.33.60/24 } } |
#分别启动两台机器上的keepalived
service keepalived start
测试：
杀掉master上的keepalived进程，你会发现，在slave机器上的eth0网卡多了一个ip地址
查看ip地址的命令： ip addr
6.配置keepalived对管理的nginx进行心跳检测
原理：
Keepalived并不跟nginx耦合，它俩完全不是一家人
但是keepalived提供一个机制：让用户自定义一个shell脚本去检测用户自己的程序，返回状态给keepalived就可以了
#MASTER节点
| global_defs { }
vrrp_script chk_health { script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1" # 自定义脚本内容 返回1表示nginx挂了,返回0表示没挂 interval 1 #每隔1秒执行上述的脚本，去检查用户的程序ngnix weight -2 # 如果本机器的nginx挂了，就降低自己的权重2 }
vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 1 priority 100 advert_int 2 authentication { auth_type PASS auth_pass 1111 }
track_script { chk_health # 用户自定义的脚本名 }
virtual_ipaddress { 10.0.0.10/24 }
notify_master "/usr/local/keepalived/sbin/notify.sh master" # 当切换到master状态时，要执行的脚本 notify_backup "/usr/local/keepalived/sbin/notify.sh backup" # 当切换到backup状态时，要执行的脚本 notify_fault "/usr/local/keepalived/sbin/notify.sh fault" # 当出现异常时，要执行的脚本 } |
#添加切换通知脚本
vi /usr/local/keepalived/sbin/notify.sh
| #!/bin/bash
case "$1" in master) /usr/local/nginx/sbin/nginx exit 0 ;; backup) /usr/local/nginx/sbin/nginx -s stop /usr/local/nginx/sbin/nginx exit 0 ;; fault) /usr/local/nginx/sbin/nginx -s stop exit 0 ;; *) echo 'Usage: notify.sh {master|backup|fault}' exit 1 ;; esac |
#添加执行权限
chmod +x /usr/local/keepalived/sbin/notify.sh
| global_defs { }
vrrp_script chk_health { script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1" interval 1 weight -2 }
vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 1 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 }
track_script { chk_health }
virtual_ipaddress { 10.0.0.10/24 }
notify_master "/usr/local/keepalived/sbin/notify.sh master" notify_backup "/usr/local/keepalived/sbin/notify.sh backup" notify_fault "/usr/local/keepalived/sbin/notify.sh fault" } |
#在第二台机器上添加notify.sh脚本
#分别在两台机器上启动keepalived
service keepalived start