Nginx+Keepalived负载均衡主从
拓扑图：
环境描述：
操作系统：CentOS6.4_x64
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 --prefix=/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
# 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;
}
}
# 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、安装keepalived
# 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 --prefix=/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
# vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
[email protected] #故障联系人
}
notification_email_from [email protected] #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 check_nginx {
script "/usr/local/nginx/check_nginx.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 { #实例引用脚本
check_nginx
}
virtual_ipaddress { #VTP
192.168.0.203
192.168.0.204
}
}
5、编写nginx_local.sh脚本
# vi check_nginx.sh #!/bin/bash Count1=`netstat -antp |grep -v grep |grep nginx |wc -l` if [ $Count1 -eq 0 ];then /usr/local/nginx/sbin/nginx Count2=`netstat -antp |grep -v grep |grep nginx |wc -l` if [ $Count2 -eq 0 ];then service keepalived stop else exit 0 fi else exit 0 fi
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。