Nginx+Keepalived实现负载均衡高可用

Nginx+Keepalived实现负载均衡高可用

一、环境
5台虚拟机，分别是：
1台测试机(192.168.2.83);
2台nginx/keepalived(192.168.2.235/192.168.2.236);
2台Web Servers(192.168.2.237/192.168.2.238);
注：VIP设置为 192.168.2.229；

二、安装配置Web Server
由于Web Server的安装与配置非常简单，根据自己喜好，安装一个即可；比如：apache、nginx、tomcat等等。在此就不再详述；

三、安装配置Nginx
yum -y install gcc vim lrzsz pcre-devel kernel-devel openssl-devel wget
wget http://nginx.org/download/nginx-1.9.0.tar.gz
tar xzvf nginx-1.9.0.tar.gz
cd nginx-1.9.0
./configure --prefix=/usr/local/nginx --with-debug --with-http_stub_status_module --with-stream --with-http_ssl_module
make;make install
ln -s /usr/local/nginx/sbin/nginx /sbin/
cd /usr/local/nginx/conf
cp nginx.conf nginx.conf.bak
编辑nginx主配置文件nginx.conf,内容大致如下：
worker_processes 10;
events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
sendfile on;
keepalive_timeout 65;
upstream html_pool {
ip_hash;
server 192.168.2.237:80;
server 192.168.2.238:80;
#server 192.168.2.239:80 backup;
#server 192.168.2.240:80 down;

}
server {
listen 80;
server_name localhost;
location / {
proxy_pass http://html_pool; proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
}
}

注：以上的操作，两台都需要操作；到此，我们的Nginx就安装及配置好了。

四、安装配置Keepalived
wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz tar xzvf keepalived-1.2.15.tar.gz
cd keepalived-1.2.15
./configure --sysconf=/etc/ --with-kernel-dir=/usr/src/kernels/2.6.32-504.23.4.el6.x86_64/
#内核参数，根据不同的操作系统，会不一样，注意更改为您服务器上的内核路径即可；
make
make install
ln -s /usr/local/sbin/keepalived /sbin/
cd /etc/keepalived/
cp keepalived.conf keepalived.conf.bak
编辑keepalive.conf主配置文件，内容大致如下：
! Configuration File for keepalived
global_defs {
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/etc/keepalived/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state MASTER/BACKUP #前主后备
interface eth0
virtual_router_id 60
priority 100/80 #前主后备
advert_int 3
authentication {
auth_type PASS
auth_pass 33333
}
virtual_ipaddress {
192.168.2.229
}
track_script {
chk_nginx
}
}

因为主配置文件里有用到一个检测nginx状态的脚本，所以另外需要创建脚本，内容如下：
# cat check_ngix.sh
#!/bin/bash
nginx_start=`ps -C nginx --no-header |wc -l`
if [ $nginx_start = 0 ]; then
#/etc/init.d/nginx start
/usr/local/nginx/sbin/nginx
sleep 3
nginx_status=`ps -C nginx --no-header |wc -l`
if [ $nginx_status = 0 ]; then
/etc/init.d/keepalived stop
fi
fi

chmod +x /etc/keepalived/check_nginx.sh
注：同样，以上的所有操作，需要两台服务器上一样操作，注意更改主备及优先级即可；到此，keepalive的相关安装与配置即OK了；

五、校验及测试
启动keepalived(两台)：/etc/init.d/keepalived start

在主服务器上随意把nginx或者keepalived服务关闭，观察服务的可用性；

如果飘到备服务器上了，同样，在备服务器上随意把nginx或者keepalived服务关闭，再观察；

最后需要注意的是，如果服务器上有启用安全软件，比如ipatalbes，一定要让服务器间相互访问，不仅仅是ping通；如：iptables -I INPUT -s 192.168.2.0/24 -j ACCEPT