nginx+keepalived主辅切换（监控脚本在keepalived.conf中执行）

以前写过一篇，nginx+keepalived 双机互备的文章，写那篇文章的时候没有想过如果apache或者nginx 挂了，而 keepalived 或者 机器没有死，那么主辅是不会切换的，今天就研究了一下该如何监控 nginx进程呢，看官方站看到了。vrrp_script 功能，但是用他的方法实在形不通，可能是我的方法不对，或者是个BUG。所以后来我自己写了个小脚本来完成工作。

环境

Server 1  :  ubuntu-server 8.04.4          192.168.6.162

Server 2  :  userver-server 8.04.4          192.168.6.188

软件

Keepalived 1.1.15

nginx-0.8.35

pcre-8.02

1.分别在两台服务器上安装nginx

tar jxvf pcre-8.02.tar.bz2 
cd pcre-8.02 
./configure --prefix=/usr --enable-utf8 --enable-pcregrep-libbz2 --enable-pcregrep-libz 
make 
make install 
tar zxvf nginx-0.8.35.tar.gz 
cd nginx-0.8.35 
--prefix=/usr/local/nginx --with-pcre --user=www --group=www --with-file-aio --with-http_ssl_module --with-http_flv_module --with-http_gzip_static_module --with-http_stub_status_module --with-cc-opt=' -O3' 
make 
make install

2.分别在两台服务器编写配置文件

vim /usr/local/nginx/conf/nginx.conf 

user    www www; 
worker_processes    1; 
error_log    logs/error.log    notice; 
pid                logs/nginx.pid; 
events { 
        worker_connections    1024; 
} 
http { 
        include             mime.types; 
        default_type    application/octet-stream; 
        sendfile                on; 
        tcp_nopush         on; 
        keepalive_timeout    65; 
        gzip    on; 
        server { 
                listen             80; 
                server_name    localhost; 
                index     index.html index.htm; 
                root        /var/www; 
                error_page     500 502 503 504    /50x.html; 
                location = /50x.html { 
                        root     html; 
                } 
        } 
} 

3.分别在两台机器创建测试文件

echo "192.168.6.162" > /var/www/index.html 
echo "192.168.6.188" > /var/www/index.html

4.安装 keepalived 

apt-get install keepalived

5.在server 1服务器编写配置文件

vrrp_script chk_http_port { 
       script "/opt/nginx_pid.sh"         ###监控脚本 
       interval 2                             ###监控时间 
       weight 2                                ###目前搞不清楚 
} 
vrrp_instance VI_1 { 
        state MASTER                            ### 设置为 主 
        interface eth0                             ### 监控网卡    
        virtual_router_id 51                    ### 这个两台服务器必须一样 
        priority 101                                 ### 权重值 MASTRE 一定要高于 BAUCKUP 
        authentication { 
              auth_type PASS             ### 加密 
              auth_pass eric                ### 加密的密码，两台服务器一定要一样，不然会出错 
        } 
        track_script { 
              chk_http_port                     ### 执行监控的服务 
        } 
        virtual_ipaddress { 
             192.168.6.7                            ###    VIP 地址 
        } 
} 

6.在 server 2 服务器 keepalived 配置

vrrp_script chk_http_port { 
        script "/opt/nginx_pid.sh" 
        interval 2 
        weight 2 
} 
vrrp_instance VI_1 { 
        state BACKUP                                ### 设置为 辅机 
        interface eth0 
        virtual_router_id 51                        ### 与 MASTRE 设置 值一样 
        priority 100                                     ### 比 MASTRE权重值 低 
        authentication { 
              auth_type PASS 
              auth_pass eric                    ### 密码 与 MASTRE 一样 
        } 
        track_script { 
              chk_http_port 
        } 
        virtual_ipaddress { 
              192.168.6.7 
        } 
}

7.编写监控nginx监控脚本

vim /opt/nginx_pid.sh 
#!/bin/bash

# varsion 0.0.2

# 根据一网友说这样做不科学，如果nginx服务起来了，但是我把keepalived 杀掉了，我的理由是，如果nginx死掉了，我觉得就很难在起来，再有就是nagios 当然要给你报警了啊。不过这位同学说的有道理，所以就稍加改了一下脚本

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
      /usr/local/nginx/sbin/nginx
      sleep 3
      if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
            killall keepalived                     ## 则结束 keepalived 进程
      fi
fi 

8、测试,分别在两个服务器 启动 nginx 和 keepalived

/usr/local/nginx/sbin/nginx 
/etc/init.d/keepalived start

监控 server 1 的日志

Apr 20 18:37:39 nginx Keepalived_vrrp: Registering Kernel netlink command channel 
Apr 20 18:37:39 nginx Keepalived_vrrp: Registering gratutious ARP shared channel 
Apr 20 18:37:39 nginx Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'. 
Apr 20 18:37:39 nginx Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'. 
Apr 20 18:37:39 nginx Keepalived_healthcheckers: Configuration is using : 3401 Bytes 
Apr 20 18:37:39 nginx Keepalived_vrrp: Configuration is using : 35476 Bytes 
Apr 20 18:37:40 nginx Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE 
Apr 20 18:37:41 nginx Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE 
Apr 20 18:37:41 nginx Keepalived_vrrp: Netlink: skipping nl_cmd msg... 
Apr 20 18:37:41 nginx Keepalived_vrrp: VRRP_Script(chk_http_port) succeeded

监控 server 2的日志 

Apr2018:38:23 varnish Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'. 
Apr 20 18:38:23 varnish Keepalived_healthcheckers: Configuration is using : 3405 Bytes 
Apr 20 18:38:23 varnish Keepalived_vrrp: Using MII-BMSR NIC polling thread... 
Apr 20 18:38:23 varnish Keepalived_vrrp: Registering Kernel netlink reflector 
Apr 20 18:38:23 varnish Keepalived_vrrp: Registering Kernel netlink command channel 
Apr 20 18:38:23 varnish Keepalived_vrrp: Registering gratutious ARP shared channel 
Apr 20 18:38:23 varnish Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'. 
Apr 20 18:38:23 varnish Keepalived_vrrp: Configuration is using : 35486 Bytes 
Apr 20 18:38:23 varnish Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE 
Apr 20 18:38:25 varnish Keepalived_vrrp: VRRP_Script(chk_http_port) succeeded 

看日志可以看出，两台服务器的 MASTRE 和 BACUKUP 已经都正常了

现在我们在 server 1 把 nginx 服务器停到

Server 1 $> killall nginx

这时候看server 1的日志

Apr 20 18:41:26 nginx Keepalived_healthcheckers: Terminating Healthchecker child process on signal 
Apr 20 18:41:26 nginx Keepalived_vrrp: Terminating VRRP child process on signal 

可以看出keepalived 的进程已经停到

这时候看server 2的日志，看是否已经接管

Apr 20 18:41:23 varnish Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE 
Apr 20 18:41:24 varnish Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE 
Apr 20 18:41:24 varnish Keepalived_vrrp: Netlink: skipping nl_cmd msg... 

很明显的看出 server 2 已经接管了，已经变为 MASTER 了

本文出自 “linuxer” 博客，请务必保留此出处http://deidara.blog.51cto.com/400447/302402