Keepalived+Nginx负载均衡双机热备

作者：zhenliang8  发布日期：2013-09-26 10:28:06

环境描述：
操作系统：CentOS6.4
master-nginx均衡器：192.168.0.202
backup-nginx均衡器：192.168.0.203
后端web1：192.168.0.204
后端web2：192.168.0.205
VTP：192.168.0.200
一、安装nginx

1、安装依赖包和创建用户和组
yum install -y gcc gcc-c++ make kernel-headers glibc-headers zlib-devel openssl openssl-devel pcre-devel
groupadd nginx
useradd -g nginx -s /sbin/nologin nginx
2、安装nginx
tar zxvf nginx-1.4.2.tar.gz
cd nginx-1.4.2
./configure --perfix=/usr/local/nginx --user=nginx --group=nginx --with-http_ssl_module --with-http_gzip_static_module --with-http_stub_status_module
make && make install
二、配置主配置文件

1、vi /usr/local/nginx/conf/nginx.conf

user nginx nginx;
worker_processes 8;
error_log logs/error.log;
pid logs/nginx.pid;
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"';
access_log logs/access.log main; #上面是访问日志格式和记录位置
sendfile on;
tcp_nopush on;
keepalive_timeout 65;
gzip on;
upstream www.test.com {
server 192.168.0.203:80 weight=2;
server 192.168.0.204:80 weight=2;
}
server {
listen 80;
server_name www.test.com;
location / {
root html;
index index.html index.htm; #请求转向mysvr 定义的服务器列表
proxy_pass http://www.test.com;
proxy_headers_hash_max_size 51200;
#设置头部哈希表的最大值，不能小于你后端服务器设置的头部总数。
proxy_headers_hash_bucket_size 6400; #设置头部哈希表大小
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
include proxy.conf;
}
}
2、vi /usr/local/nginx/conf/proxy.conf

proxy_redirect off;
proxy_set_header Host $host; #后端的Web服务器可以通过X-Forwarded-For获取用户真实IP
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
client_max_body_size 10m; #允许客户端请求的最大单文件字节数
client_body_buffer_size 128k; #缓冲区代理缓冲用户端请求的最大字节数，
proxy_connect_timeout 90; #nginx跟后端服务器连接超时时间(代理连接超时)
proxy_read_timeout 90; #连接成功后，后端服务器响应时间(代理接收超时)
proxy_buffer_size 4k; #设置代理服务器（nginx）保存用户头信息的缓冲区大小
proxy_buffers 6 32k; #proxy_buffers缓冲区，网页平均在32k以下的话，这样设置
proxy_busy_buffers_size 64k; #高负荷下缓冲大小（proxy_buffers*2）
proxy_temp_file_write_size 64k; #设定缓存文件夹大小，大于这个值，将从upstream服务器传
三、安装主从keepalived （配置基本一样，主配置文件稍作修改）
1、安装依赖包：
yum install -y pcre pcre-devel openssl-devel lftp libnl-devel popt*
2、wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
tar zxvf keepalived-1.2.7.tar.gz
cd keepalived-1.2.7
./configure /usr/local/keepalived
make && make install
3、keepalived配置成系统服务
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
4、修改keepalived主配置

! Configuration File for keepalived
global_defs {
notification_email {
[e-mail] #故障联系人
}
notification_email_from [e-mail] #故障发送人
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_MASTER #BACKUP上修改为LVS_BACKUP
}
vrrp_script chk_http_port {
script "/usr/local/nginx/nginx_local.sh" #检测nginx脚本路径
interval 2 #监控时间/秒
}
vrrp_instance VI_1 {
state MASTER #BACKUP上修改为BACKUP
interface eth0
virtual_router_id 51
priority 100 #BACKUP上修改为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script { #使用上面检测脚本
chk_http_port
}
virtual_ipaddress { #VTP
192.168.0.203
192.168.0.204
}
}
5、编写nginx_local.sh脚本

#!/bin/bash
NGINX1=`netstat -tupln |grep 80 |wc -l`
if [ $NGINX1 -eq 0 ]
then
/usr/local/nginx/sbin/nginx
NGINX2=`netstat -tupln |grep 80 |wc -l`
if [ $NGINX2 -eq 0 ]
then
service keepalived stop
else
echo "Nginx again running!!!"
fi
fi
语句说明：当NGINX1等于0，也就是nginx关闭时，尝试重启nginx服务，如果启动成功，NGINX1和NGINX2变量是一样作用，则显示Nginx again running!!!，如果启动失败，就关闭keepalived。
6、重新启动：service keepalived restart
/usr/local/nginx/sbin/nginx -s reload

四、其他说明
实验中遇到一个问题，当keepalived或服务器没有DOWN时，主从服务器不会切换，所以就使用vrrp_script功能，写了个简单的检测脚本，nginx服务启动不起来时，就关闭keepalived，从而确保能主从切换。
1.常用命令：
ipvsadm -ln #显示集群中服务器ip信息
ip add #显示VTP绑定在哪个服务器上

/usr/local/nginx/sbin/nginx #启动nginx
/sbin/nginx -s stop #快速终止web服务
/sbin/nginx -s quit #有安排的结束web服务
/sbin/nginx -s reload #重新加载相关配置
echo '/usr/local/nginx/sbin/nginx' >> /etc/rc.local #设置开机启动

2.tail -f /var/log/messger(从日志中可知，主机出现故障后，备机立刻检测到，此时备机变为MASTER角色，并且接管了主机的虚拟IP资源，最后将虚拟IP绑定在eth0设备上)
3.当主LVS恢复后，会切换成主动服务器，如果Keepalived监控模块检测web故障恢复后，恢复的wen主机又将此节点加入集群系统中。