Nginx负载均衡器+Keepalvied双机互备+tomcat集群

Nginx作负载均衡器的优点许多，简单概括为:①实现了可弹性化的架构，在压力增大的时候可以临时添加tomcat服务器添加到这个架构里面去;②upstream具有负载均衡能力，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；而Keepalvied可保证单个nginx负载均衡器的有效性，避免单点故障，整个拓补如下：

nginx(主负载均衡器)：192.168.1.106
nginx(从负载均衡器)：192.168.1.107
VIP地址:                      192.168.1.108
tomcat1的IP              192.168.1.102
tomcat2的IP                192.168.1.103
tomcat3的IP                192.168.1.105

布置整个环境用到的软件为:
apache-tomcat-6.0.20.tar.gz
jdk-6u16-linux-i586.bin
nginx-0.7.17.tar.gz
prce-7.7.tar.gz

①首先分别在3台tomcat主机上布置java环境，安装tomcat，具体步骤为：
apache-tomcat-6.0.tar.gz可在apache.org上下载，jdk-6u16-linux-i586.bin我是用文件挖掘者直接搜索下载的http://www.fdigg.net/search_jdk-6-linux-i586.htm。
第一步，安装java环境。
JDK的安装
#chmod +x jdk-6u16-linux-i586.bin
#./jdk-6u16-linux-i586.bin
到此JDK已经安装完成
建立符号链接
# ln -s /usr/local/jdk-1.6.0-16/bin/java /usr/bin/java
# ln -s /usr/local/jdk-1.6.0-16/bin/javac /usr/bin/javac
ln -s /usr/local/jdk-1.6.0-16 /usr/local/jdk
ln -s /usr/local/jdk-1.6.0-16/jre /usr/local/jre
TOMCAT的安装
#tar zxvf apache-tomcat-6.0.20.tar.gz
#mv apache-tomcat-6.0.20 /usr/local/tomcat

设置环境变量: vim /etc/rc.d/rc.local，以追加的形式添加如下内容
JAVA_HOME=/usr/local/jdk
export JAVA_HOME
JRE_HOME=/usr/local/jre
export JRE_HOME
CLASSPATH=/usr/local/tomcat/common/lib/:/usr/local/jdk/lib:/usr/local/jre/lib
export CLASSPATH
PATH=$PATH:/usr/local/tomcat/bin/:/usr/local/apache/bin:/usr/local/jdk/bin:/usr/local/jre/bin
export PATH
TOMCAT_HOME=/usr/local/tomcat
export TOMCAT_HOME
重启服务器，启动tomcat以检查是否存在错误：
#cd /usr/local/tomcat/bin
#./startup.sh
http://IP地址:8080 可以看到猫头:)成功了。

②分别在二台nginx负载均衡器上安装nginx及配置
下载及安装nginx:
wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-7.7.tar.gz
tar zxvf pcre-7.7.tar.gz
cd pcre-7.7/
./configure
make && make install
wget http://sysoev.ru/nginx/nginx-0.7.17.tar.gz
tar zxvf nginx-0.7.17.tar.gz
cd nginx-0.7.17/
./configure --prefix=/usr/local/nginx --with-http_stub_status_module
make && make install

这里贴上nginx.conf配置文件，不加任何说明，方便用X-shell直接粘贴，很人性化的噢:)二个nginx负载均衡器的文件一样，配置完成后分别用/usr/local/nginx/sbin/nginx启动。
user nobody nobody;
worker_processes 1;
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;
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;
keepalive_timeout 60;
tcp_nodelay on;
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;
gzip_min_length 1k;
gzip_buffers     4 16k;
gzip_http_version 1.0;
gzip_comp_level 2;
gzip_types       text/plain application/x-javascript text/css application/xml;
gzip_vary on;
upstream backend
{
server 192.168.1.102:8080;
server 192.168.1.103:8080;
server 192.168.1.105:8080;
}
server {
listen 80;
server_name www.yuhongchun027.com;
location / {
root /var/www ;
index index.jsp index.htm index.html;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://backend;
}

#location /nginx {
#access_log on;
#auth_basic "NginxStatus";
#auth_basic_user_file /usr/local/nginx/htpasswd;
#}
log_format access '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" $http_x_forwarded_for';
access_log /var/log/access.log access;
}
}

③在二台Nginx机上安装及配置keepalived，做双机互备。
#wget http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
#tar zxvf keepalived-1.1.15.tar.gz
#cd keepalived-1.1.15
#./configure
#make
#make install
将keepalived做成启动脚务，方便管理:
#cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
#mkdir /etc/keepalived
#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
#cp /usr/local/sbin/keepalived /usr/sbin/
#service keepalived start|stop

在二台Nginx上，我分别贴出keepalived.conf配置文件，配置完成后分别用service keepalived start启动。检验keepalived是否成功可用命令ip a
vrrp_instance VI_INET1 {
        state MASTER
        interface eth0
        virtual_router_id 53
        priority 200
        advert_int 1
        authentication {
                auth_type pass
                auth_pass yourpass
        }
        virtual_ipaddress {
                192.168.1.108
        }
}

vrrp_instance VI_INET1 {
        state BACKUP
        interface eth0
        virtual_router_id 53
        priority 100
        advert_int 1
        authentication {
                auth_type pass
                auth_pass yourpass
        }
        virtual_ipaddress {
                192.168.1.108
        }
}

以上三步完成后，就是检测了，大家可任意停掉其中一台的任何服务；在正常结果中大家应该发现，其中任意一台服务器宕机后，不影响整个系统的运作。如对以上实验过程有疑问，欢迎来信交流[e-mail](抚琴煮酒)