nginx

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

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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

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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

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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

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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

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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

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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 

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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

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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

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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

转自：http://deidara.blog.51cto.com/400447/302402