Nginx负载均衡（主备）+Keepalived
Nginx负载均衡器的优点:
实现看弹性化操作的架构，压力增大的时候可以临时添加后端Web服务器；
upstream具有负载均衡能力(默认使用轮询)，可以自动判断下面的机器，并且自动踢出不能正常提供服务的机器；
Keepalvied加Nginx监测脚本可保证单个nginx负载均衡器的有效性,避免单点故障
系统
两台Nginx：
CentOS6.7 x86_64
两台Web：
Ubuntu15.04 desktop
拓扑
IP地址
nginx(主LB):192.168.15.132
nginx(备LB):192.168.15.133
VIP地址:192.168.15.135
Real1的IP:192.168.15.128
Real2的IP:192.168.15.130
部署整个环境用到的软件为:
nginx-1.6.3.tar.gz
prce-8.38.tar.gz
zlib-1.2.8.tar.gz
①2台Web主机（Ubuntu）上部署Nginx+PHP-FPM+MySQL，此处省略。
②分别在二台Nginx负载均衡器上安装Nginx，配置
安装GCC编译器等工具：
yum install -y gcc gcc-c++ autoconf automake libtool make openssl openssl-devel
安装Nginx:
wget http://exim.mirror.fr/pcre/pcre-8.38.tar.gz
tar -zxvf pcre-8.38.tar.gz
cd pcre-8.38
./configure
make && make install
wget http://zlib.net/zlib-1.2.8.tar.gz
tar -zxvf zlib-1.2.8.tar.gz
cd zlib-1.2.8
./configure
make && make install
wget http://nginx.org/download/nginx-1.6.3.tar.gz
tar -zxvf nginx-1.6.3.tar.gz
cd nginx-1.6.3/
./configure --prefix=/usr/local/nginx
--sbin-path=/usr/local/nginx/sbin/nginx
--conf-path=/usr/local/nginx/conf/nginx.conf
--pid-path=/usr/local/nginx/logs/nginx.pid \
--with-http_ssl_module \
--with-http_stub_status_module \
--with-http_gzip_static_module \
make && make install
注：查询"./configure --help"相关模块，按需求指定启用
Nginx.conf配置文件，二个nginx负载均衡器的文件一样
user www-data www-data;
worker_processes 1;
error_log /usr/local/nginx/logs/error.log notice;
pid /usr/local/nginx/logs/nginx.pid;
worker_rlimit_nofile 51200;
events {
use epoll;
worker_connections 51200;
}
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;
server_names_hash_bucket_size 128;
client_header_buffer_size 32k;
large_client_header_buffers 4 32k;
client_max_body_size 8m;
sendfile on;
tcp_nopush on;
server_tokens off;
keepalive_timeout 60;
fastcgi_connect_timeout 300;
fastcgi_send_timeout 300;
fastcgi_read_timeout 300;
fastcgi_buffer_size 64k;
fastcgi_buffers 4 64k;
fastcgi_busy_buffers_size 128k;
fastcgi_temp_file_write_size 128k;
gzip on;
upstream backend
{
server 192.168.15.128;
server 192.168.15.130;
}
server {
listen 80;
server_name 192.168.15.135;
location / {
root html;
index index.php index.html index.htm;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
#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-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://backend;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
location /nginx_status {
stub_status on;
auth_basic "NginxStatus";
auth_basic_user_file /usr/local/nginx/htpasswd;
#allow 127.0.0.1;
#deny all;
}
location ~* \.(ini|docx|txt|doc|pdf)$ {
#禁止访问文档性文件
root /usr/share/nginx/html;
deny all;
}
location ~ .*\.(gif|jpg|jpeg|png|bmp|swf|js|html|htm|css)$ {
root /home/image;
proxy_store on;
proxy_store_access user:rw group:rw all:rw;
proxy_temp_path /home/image;
if ( !-e $request_filename) {
proxy_pass http://backend;
}
}
}
}
③在二台Nginx上安装及配置keepalived：
wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz
tar -zxvf keepalived-1.2.15.tar.gz
cd keepalived-1.2.15
./configure --sysconf=/etc/ --with-kernel-dir=/usr/src/kernels/2.6.32-573.8.1.el6.x86_64
make && make install
ln -s /usr/local/sbin/keepalived /sbin/
#这一步很重要，不执行ln -s会报错“Starting keepalived: /bin/bash: keepalived: command not found”
service keepalived start
二台Nginx上keepalived.conf配置文件如下，配置完成后分别service keepalived start启动｡检验keepalived配置是否成功
主：
global_defs {
notification_email {
[email protected]
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_MASTER
}
vrrp_script chk_http_port {
script "/usr/local/src/check_nginx_pid.sh"
interval 2 #（检测脚本执行的间隔）
weight 2
}
vrrp_instance VI_1 {
#state MASTER
state BACKUP
nopreempt
#设置非抢占模式时，需修改“state MASTER”为“state BACKUP”，添加“nopreempt“
interface bond0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_http_port #（调用检测脚本）
}
virtual_ipaddress {
192.168.15.135/24 broadcast 192.168.15.255 dev bond0 label bond0:1
}
}
备：
global_defs {
notification_email {
[email protected]
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_BACKUP
}
vrrp_script chk_http_port {
script "/usr/local/src/check_nginx_pid.sh"
interval 2 #（检测脚本执行的间隔）
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface bond0
virtual_router_id 51
priority 66
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_http_port #（调用检测脚本）
}
virtual_ipaddress {
192.168.15.135/24 broadcast 192.168.15.255 dev bond0 label bond0:1
}
}
以下是针对nginx状态进行检测的脚本，第一次nginx服务死掉时，会重新启动，如果Nginx服务无法正常启动，则杀掉keepalived进程
vim /usr/local/src/check_nginx_pid.sh
#!/bin/bash A=`ps -C nginx --no-header |wc -l` if [ $A -eq 0 ];then /usr/local/nginx/sbin/nginx if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then killall keepalived fi fi
Ok，开始nginx负载均衡测试，停掉其中一台的任何服务，不影响整个系统的运作｡
注：两台LBServer也可分别添加一个VIP①②（Keepalived心跳监控，服务不可用或者宕机，VIP①被备LBServer接管），外部使用智能DNS轮询两个VIP①②，提高硬件资源利用率。