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

nginx+keepalived 双机互备_双机互备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