7.Nginx_Keepalived高可用配置
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2. 利用keepalived实现高可靠配置(HA)
2.1. 高可靠概念
HA(High Available):高可用性集群,是保证业务连续性的有效解决方案,一般有两个或两个以上的节点,且分为活动节点及备用节点。
2.2. 高可靠软件keepalived
keepalive是一款可以实现高可靠的软件,通常部署在2台服务器上,分为一主一备。Keepalived可以对本机上的进程进行检测,一旦Master检测出某个进程出
现问题,将自己切换成Backup状态,然后通知另外一个节点切换成Master状态。
2.3. keepalived安装
下载keepalived官网:http://keepalived.org
将keepalived解压到/usr/local/src目录下:tar -zxvf keepalived-1.2.19.tar.gz -C /usr/local/src
进入到/usr/local/src/keepalived-1.2.19目录:cd /usr/local/src/keepalived-1.2.19
开始configure(检查安装环境,并指定将来要安装的路径):./configure --prefix=/usr/local/keepalived
#编译并安装:make && make install
2.4. 将keepalived添加到系统服务中
拷贝执行文件:cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
将init.d文件拷贝到etc下,加入开机启动项:cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
将keepalived文件拷贝到etc下:cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
创建keepalived文件夹:mkdir -p /etc/keepalived
将keepalived配置文件拷贝到etc下:cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
添加可执行权限:chmod +x /etc/init.d/keepalived
添加keepalived到开机启动:chkconfig --add keepalived chkconfig keepalived on
2.4. 配置keepalived虚拟IP
1.基本服务器宕机的主从切换配置
机器IP |
安装软件 |
角色 |
虚拟ip |
描述 |
192.168.232.201 |
nginx、keepalived |
Nginx主机 |
192.168.232.203 |
反向代理到tomcat1和tomcat2 |
192.168.232.205 |
Nginx、keepalived |
Nginx备机 |
主机挂了切换虚拟ip 192.168.232.203 |
反向代理到tomcat1和tomcat2 |
192.168.232.200 |
Tomcat |
Tomcat1 |
无 |
|
192.168.232.204 |
Tomcat |
Tomcat2 |
无 |
两台nginx服务器,分别安装keepalived,配置/etc/keepalived/keepalived.conf
主从配置:
主nginx修改配置文件: /etc/keepalived/keepalived.conf
#MASTER节点
#全局配置
global_defs {
notification_email { #指定keepalived在发生切换时需要发送email到的对象,一行一个
XXX@XXX.com
}
notification_email_from Alexandre.Cassen@firewall.loc #指定发件人
smtp_server 192.168.200.1 #指定smtp服务器地址
smtp_connect_timeout 30 #指定smtp连接超时时间
router_id LVS_DEVEL #运行keepalived机器的一个标识
}
vrrp_instance VI_1 {
state MASTER #指定A节点为主节点 备分机上设置为BACKUP即可
interface eth0 #设置实例绑定的网卡
virtual_router_id 51 #VRRP组名,两个节点的设置必须一样,以指明各个节点属于同一VRRP组(同一实例下virtual_router_id必须相同)
priority 100 #主节点的优先级(1-254之间),备用节点必须比主节点优先级低
advert_int 1 #MASTER与BACKUP负载均衡器之间同步检查的时间间隔,单位是秒
authentication { #设置验证信息,两个节点必须一致
auth_type PASS #主从服务器验证方式
auth_pass 1111
}
virtual_ipaddress { #指定虚拟IP, 两个节点设置必须一样
192.168.232.203/24 #如果两个nginx的ip分别是192.168.232.201,,...205,则此处的虚拟ip跟它俩同一个网段即可,24子网掩码(255.255.255.0),可以多个虚拟IP,换行即可
}
}
备nginx
修改备nginx下/etc/keepalived/keepalived.conf文件
配置备nginx时需要注意:需要修改state为BACKUP , priority比MASTER低,virtual_router_id和master的值一致
#BACKUP节点
global_defs {
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.232.203/24
}
}
#分别启动两台机器上的keepalived:tail /var/log/message 查看日志。
service keepalived start
用ip addr查看主从:
主机:
备机:
此时如果主机宕机则(service keepalived stop)备机会顶替主机获得虚拟ip
首先将主机的keepalived关闭:
再次查看主机:ip addr
备机:
至此,基本服务器宕机的主从切换配置完毕
访问虚拟ip是不是还能轮询访问tomcat
2.基于nginx进程死掉的主从切换配置
keepalived是通过检测keepalived进程是否存在判断服务器是否宕机,如果keepalived进程在但是nginx进程不在了那么keepalived是不会做主备切换,所以我们需要写
个脚本来监控nginx进程是否存在,如果nginx不存在就将keepalived进程杀掉。
在主nginx上需要编写nginx进程检测脚本(check_nginx.sh),判断nginx进程是否存在,如果nginx不存在就将keepalived进程杀掉,check_nginx.sh内容如下:
#!/bin/bash
# 如果进程中没有nginx则将keepalived进程kill掉
A=`ps -C nginx --no-header |wc -l` ## 查看是否有 nginx进程 把值赋给变量A
if [ $A -eq 0 ];then ## 如果没有进程值得为 零
service keepalived stop ## 则结束 keepalived 进程
fi
将check_nginx.sh拷贝至/etc/keepalived下,
注意修改/etc/keepalived/check_nginx.sh的可执行权限
修改主nginx的keepalived.conf,添加脚本定义检测:
注意下边红色标识地方:
#全局配置
global_defs {
notification_email { #指定keepalived在发生切换时需要发送email到的对象,一行一个
XXX@XXX.com
}
notification_email_from miaoruntu@itcast.cn #指定发件人
#smtp_server XXX.smtp.com #指定smtp服务器地址
#smtp_connect_timeout 30 #指定smtp连接超时时间
router_id LVS_DEVEL #运行keepalived机器的一个标识
}
vrrp_script check_nginx {
script "/etc/keepalived/check_nginx.sh" ##监控脚本
interval 2 ##时间间隔,2秒
weight 2 ##权重
}
vrrp_instance VI_1 {
state MASTER #标示状态为MASTER 备份机为BACKUP
interface eth0 #设置实例绑定的网卡
virtual_router_id 51 #同一实例下virtual_router_id必须相同
priority 100 #MASTER权重要高于BACKUP 比如BACKUP为99
advert_int 1 #MASTER与BACKUP负载均衡器之间同步检查的时间间隔,单位是秒
authentication { #设置认证
auth_type PASS #主从服务器验证方式
auth_pass 8888
}
track_script {
check_nginx #监控脚本
}
virtual_ipaddress { #设置vip
192.168.101.100 #可以多个虚拟IP,换行即可
}
}
修改后重启keepalived
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