nginx学习（三）——nginx高可用方案nginx+keepalived

upstream testtomcat  {
    server 192.168.126.99:8081 weight=3;
    server 192.168.126.99:8082 weight=1;
    server 192.168.126.99:8083 weight=1;
}
server {
    listen       80;
    server_name  localhost;

    #charset koi8-r;

    #access_log  logs/host.access.log  main;
    location / {
    proxy_pass  http://testtomcat;
    }
}

# 解压keepalived安装包
tar -zxvf keepalived-2.0.19.tar.gz -C /usr/local/server  #解压keepalived到指定目录

#进入解压包
cd /usr/local/server/keepalived-2.0.19

# 执行命令生成MakeFile
./configure --prefix=/usr/local/server/keepalived

# 编译和安装
make && make install

# 创建一个keepalived配置目录， keepalived启动时默认去这个路径加载配置文件
mkdir /etc/keepalived

# 复制配置
cp /usr/local/server/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

#复制 keepalived 服务脚本到默认的地址

cp /usr/local/server/keepalived/sbin/keepalived /etc/init.d/ #2.0.19版本
cp /usr/local/server/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

#拷贝执行文件至 /usr/sbin/ ，可直接根据执行文件在任何地方执行
cp /usr/local/server/keepalived/sbin/keepalived /usr/sbin/ 

# 创建执行文件keepalived的软连接到 /usr/sbin/ 目录中。可在系统任何地方输入keepalived执行。
ln -s /usr/local/server/keepalived/sbin/keepalived /usr/sbin/ 

#设置 keepalived 服务开机启动
chkconfig keepalived on

global_defs {
   router_id keep99;
}

vrrp_script chk_nginx {
 script "/etc/keepalived/nginx_check.sh"
 interval 2 
 weight -20 
}


vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 99
    mcast_src_ip 192.168.126.99
    priority 100
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS  
        auth_pass 1111 
    }

    track_script {
     chk_nginx
    }
    virtual_ipaddress {
        192.168.126.98 
    }
}

#添加keep99主机名
vim /etc/hosts

global_defs {
   router_id keep100
}

vrrp_script chk_nginx {
 script "/etc/keepalived/nginx_check.sh"
 interval 2
 weight -20
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 100
    priority 90
    mcast_src_ip 192.168.126.100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
    chk_nginx
    }
    virtual_ipaddress {
        192.168.126.98
    }
}

global_defs {
 ## keepalived 自带的邮件提醒需要开启 sendmail 服务。建议用独立的监控或第三方 SMTP 
 router_id keep99 ## 标识本节点的字条串，通常与host文件的主机名一致，访问keep99就是访问主机
}
## keepalived 会定时执行脚本并对脚本执行的结果进行分析，动态调整 vrrp_instance 的优先级。如果
脚本执行结果为 0，并且 weight 配置的值大于 0，则优先级相应的增加。如果脚本执行结果非 0，并且 weight
配置的值小于 0，则优先级相应的减少。其他情况，维持原本配置的优先级，即配置文件中 priority 对应
的值。
vrrp_script chk_nginx {
 script "/etc/keepalived/nginx_check.sh" ## 检测 nginx 状态的脚本路径
 interval 2 ## 检测时间间隔
 weight -20 ## 如果条件成立，权重-20
}
## 定义虚拟路由，VI_1 为虚拟路由的标示符，自己定义名称
vrrp_instance VI_1 {
 state MASTER ## 主节点为 MASTER，对应的备份节点为 BACKUP
 interface ens33 ## 绑定虚拟 IP 的网络接口，我的是 ens33
 virtual_router_id 99 ## 虚拟路由的 ID 号，两个节点设置必须一样，可选 IP 最后一段使用, 相
同的 VRID 为一个组，他将决定多播的 MAC 地址
 mcast_src_ip 192.168.126.99 ## 本机 IP 地址
 priority 100 ## 节点优先级，值范围 0-254，MASTER 要比 BACKUP 高
nopreempt ## 优先级高的设置 nopreempt 解决异常恢复后再次抢占的问题
advert_int 1 ## 组播信息发送间隔，两个节点设置必须一样，默认 1s
## 设置验证信息，两个节点必须一致
authentication {
 auth_type PASS
 auth_pass 1111 ## 真实生产，按需求对应该过来
}
## 将 track_script 块加入 instance 配置块
 track_script {
 chk_nginx ## 执行 Nginx 监控的服务
}
## 虚拟 IP 池, 两个节点设置必须一样
 virtual_ipaddress {
    192.168.126.98 ## 虚拟 ip，可以定义多个
 }
}

# 覆盖主节点以及副节点目录 /etc/keepalived/下的keepalived.conf 配置
cp /usr/local/server/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

#!/bin/bash
A=`ps -C nginx –no-header |wc -l`
if [ $A -eq 0 ];then
   # 尝试重新启动nginx  
   # /usr/local/myserver/nginx/sbin/nginx 

   # 此操作睡眠2秒
   # sleep 2

   # 如发现nginx挂掉，直接kill进程
    if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
        killall keepalived
    fi
fi