nginx+tomcat实现负载均衡，使用redis session共享

环境准备

1、准备一台nginx服务器 ip192.168.1.133 端口81

安装过程：

＃首先安装依赖：
yum -y install gcc-c++ 
yum -y install pcre pcre-devel 
yum -y install zlib zlib-devel 
yum -y install openssl openssl—devel
#注意 ： 安装nginx必须使用 root 用户安装
#创建一个nginx目录
mkdir /usr/local/src/nginx
#进入到nginx目录
cd /usr/local/src/nginx
#下载或上传安装包
wget http://nginx.org/download/nginx.tar.gz 或 rz上传
#解压安装包
tar -xvf nginx.tar.gz
#进入到解压后的目录
cd nginx
# 下面 才开始正式安装
#把nginx安装到指定用户的目录
mkdir -p /ucenter/soft/nginx
#安装配置 prefix为安装目录 user为用户 group为 组
./configure --prefix=/ucenter/soft/nginx --user=ucenter --group=ucenter
#编译
make 
#安装
make install
#在linux系统中由于非root用户不能占用80端口，所以需要使普通用户以root身份启动nginx。 
cd /ucenter/soft/nginx/sbin
#把soft文件下所有的文件所属者修改为ucener -R 表示递归
chown ucenter:ucenter ./soft/ -R
#修改 ./nginx 的所属为root
chown root nginx
#让普通用户可以使用80端口，可以使用root权限启用nginx
chmod u+s nginx
#修改配置文件 在修改配置文件之前 ，要备份该文件
cd conf/
# 要注意nginx 的工作进程，一般根据cpu的核数去修改
vim nginx.conf
#关闭防火墙，打开80端口
service iptables stop
#启动nginx
./nginx
#重启nginx
./nginx -s reload
#关闭nginx
./nginx -s stop

准备一台tomcat服务器，先准备java环境，安装jdk步骤省略

然后分别安装3个tomcat 服务器ip地址：192.168.1.143，tomcat1 8080端口，tomcat2 8081端口，tomcat3 8082端口。

apache-tomcat-7.0.64/conf/server.xml配置文件修改这三个地方，这样端口就不会冲突

修改tomcat ROOT目录下index.jsp，分别增加每个tomcat的标识，以及在页面上显示session ID

<%-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR ConDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --%> <%@ page session="true" %> <% java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy"); request.setAttribute("year", sdf.format(new java.util.Date())); request.setAttribute("tomcatUrl", "http://tomcat.apache.org/"); request.setAttribute("tomcatDocUrl", "/docs/"); request.setAttribute("tomcatExamplesUrl", "/examples/"); %> <%=request.getServletContext().getServerInfo() %> Home--<%=request.getSession().getId() %> documentation Configuration Examples Wiki Mailing Lists Find Help
${pageContext.servletContext.serverInfo}--8080 If you're seeing this, you've successfully installed Tomcat. Congratulations!

Recommended Reading: Security Considerations HOW-TO Manager Application HOW-TO Clustering/Session Replication HOW-TO Server Status Manager App Host Manager
Developer Quick Start

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JDBC DataSources

Examples

Servlet Specifications

Tomcat Versions

Managing Tomcat

For security, access to the manager webapp is restricted. Users are defined in:

$CATALINA_HOME/conf/tomcat-users.xml

In Tomcat 7.0 access to the manager application is split between different users. Read more...

Release Notes Changelog Migration Guide Security Notices documentation Tomcat 7.0 documentation Tomcat 7.0 Configuration Tomcat Wiki

Find additional important configuration information in:

$CATALINA_HOME/RUNNING.txt

Developers may be interested in:

Tomcat 7.0 Bug Database
Tomcat 7.0 JavaDocs
Tomcat 7.0 SVN Repository

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这时候修改nginx配置文件nginx.conf，把三台tomcat的ip地址以及端口号加入进去，使用nginx做代理

#user nobody;
worker_processes 1;

#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;

#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;

 sendfile  on;
 #tcp_nopush  on;

 #keepalive_timeout 0;
 keepalive_timeout 65;

 #gzip on;

 upstream localhost1 { 
  
   #ip_hash; 
   server 192.168.1.143:8080; 
   server 192.168.1.143:8081; 
   server 192.168.1.143:8082; 
 } 

 server {
  listen  81;
  server_name localhost;

  #charset koi8-r;

  #access_log logs/host.access.log main;

  location / {
    proxy_connect_timeout 3; 
    proxy_send_timeout  30; 
    proxy_read_timeout  30; 
    proxy_pass http://localhost1; 
  }

  #error_page 404    /404.html;

  # redirect server error pages to the static page /50x.html
  #
  error_page 500 502 503 504 /50x.html;
  location = /50x.html {
   root html;
  }

  # proxy the PHP scripts to Apache listening on 127.0.0.1:80
  #
  #location ~ .php$ {
  # proxy_pass http://127.0.0.1;
  #}

  # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
  #
  #location ~ .php$ {
  # root   html;
  # fastcgi_pass 127.0.0.1:9000;
  # fastcgi_index index.php;
  # fastcgi_param script_FILENAME /scripts$fastcgi_script_name;
  # include  fastcgi_params;
  #}

  # deny access to .htaccess files, if Apache's document root
  # concurs with nginx's one
  #
  #location ~ /.ht {
  # deny all;
  #}
 }


 # another virtual host using mix of IP-, name-, and port-based configuration
 #
 #server {
 # listen  8000;
 # listen  somename:8080;
 # server_name somename alias another.alias;

 # location / {
 #  root html;
 #  index index.html index.htm;
 # }
 #}


 # HTTPS server
 #
 #server {
 # listen  443;
 # server_name localhost;

 # ssl     on;
 # ssl_certificate  cert.pem;
 # ssl_certificate_key cert.key;

 # ssl_session_timeout 5m;

 # ssl_protocols SSLv2 SSLv3 TLSv1;
 # ssl_ciphers HIGH:!aNULL:!MD5;
 # ssl_prefer_server_ciphers on;

 # location / {
 #  root html;
 #  index index.html index.htm;
 # }
 #}

}

这时候，分别启动三台tomcat以及nginx，访问http://192.168.1.133:81，这时候每次刷新页面，都会随机访问8080或者8081或者8082，而且页面上出现的session id也都是不一样的，我们应该如何让这三台tomcat共享session呢，我们使用redis来做。

这时候，在已经按照三台tomcat的服务器192.168.1.143上，安装redis，安装步骤如下：

$ wget http://download.redis.io/releases/redis-3.2.3.tar.gz
$ tar xzf redis-3.2.3.tar.gz
$ cd redis-3.2.3
$ make MALLOC=libc
#启动redis src前面是安装的路径
$ src/redis-server &

#关闭redis
src/redis-cli shutdown
#使用redis 放入键值对 key value
$ src/redis-cli
127.0.0.1:6379> set foo bar
OK
127.0.0.1:6379> get foo
"bar"
$

安装完redis之后，在三个tomcat的lib文件夹内分别上传这五个所依赖的jar，分别是

commons-pool2-2.0.jar

jedis-2.5.2.jar

tomcat-redis-session-manager1.2.jar

tomcat-juli.jar

tomcat-juli-adapters.jar

所有jar在这里了，下载地址

然后分别修个三个tomcat的context.xml文件，增加如下的配置