nginx+tomcat负载均衡和session复制

小灰灰 2022-07-16 06:07 119阅读 0赞

本文介绍下传统的tomcat负载均衡和session复制. session复制是基于JVM内存的，当然在当今的互联网大数据时代，有更好的替代方案，如将session数据保存在Redis中.

##  1、安装nginx ##

首先下载nginx，我下载的版本是1.11.4版本 .http://nginx.org/download/nginx-1.11.4.zip .

下载后，解压.

![Center][]

安装完成之后，配置下conf目录下的nginx.conf文件.

主要添加了如下内容：

#tomcat的三个服务
          upstream mysite {
          server localhost:18080 weight=5;
          server localhost:28080 weight=5;
          server localhost:38080 weight=5;
            }

proxy_pass http://mysite;  
                #添加如下3个配置后，当一台server宕机,切换速度会很快，此时配置是1秒  
                proxy_connect_timeout   1;   
                proxy_send_timeout      1;  
                proxy_read_timeout      1;

完整的文件如下：

#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  10;
    
        #gzip  on;
        
        
        #tomcat的三个服务
        upstream mysite {
          server localhost:18080 weight=5;
          server localhost:28080 weight=5;
          server localhost:38080 weight=5;
        }
    
        server {
            listen       80;
            server_name  localhost;
    
            #charset koi8-r;
    
            #access_log  logs/host.access.log  main;
    
            location / {
                root   html;
                index  index.html index.htm;
                proxy_pass http://mysite;
                #添加如下3个配置后，当一台server宕机,切换速度会很快，此时配置是1秒
                proxy_connect_timeout   1; 
                proxy_send_timeout      1;
                proxy_read_timeout      1;
            }
    
            #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 ssl;
        #    server_name  localhost;
    
        #    ssl_certificate      cert.pem;
        #    ssl_certificate_key  cert.key;
    
        #    ssl_session_cache    shared:SSL:1m;
        #    ssl_session_timeout  5m;
    
        #    ssl_ciphers  HIGH:!aNULL:!MD5;
        #    ssl_prefer_server_ciphers  on;
    
        #    location / {
        #        root   html;
        #        index  index.html index.htm;
        #    }
        #}
    
    }

## 2、Tomcat配置 ##

下载tomcat之后, 新建三个文件夹tomcat1、tomcat2、tomcat3，把解压后的文件分别复制进这三个文件夹中，更改每个tomcat目录下的server.xml文件.

更改server和Connector端口. tomcat1 中server的端口为18005,Connector端口为18080,；tomcat2的分别是28005,28080；tomcat3分别是38085 ,38080。

为了session复制，还需要对server.xml做如下配置：

（1）取消Cluster节点的注释. （2）保持每个Engine 节点jvmRoute的值是相同的.

如下是tomcat1中的server.xml配置文件:

<?xml version="1.0" encoding="UTF-8"?>
    
    
    <Server port="18005" shutdown="SHUTDOWN">
      <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
      
      
      <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
      
      <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
      <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
      <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />
    
      
      <GlobalNamingResources>
        
        <Resource name="UserDatabase" auth="Container"
                  type="org.apache.catalina.UserDatabase"
                  description="User database that can be updated and saved"
                  factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
                  pathname="conf/tomcat-users.xml" />
      </GlobalNamingResources>
    
      
      <Service name="Catalina">
    
        
        
    
    
        
        <Connector port="18080" protocol="HTTP/1.1"
                   connectionTimeout="20000"
                   redirectPort="8443" />
        
        
        
        
        
        
    
        
        <Connector port="18009" protocol="AJP/1.3" redirectPort="8443" />
    
    
        
    
        
        <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    
          
         
          <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      
    
          
          <Realm className="org.apache.catalina.realm.LockOutRealm">
            
            <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
                   resourceName="UserDatabase"/>
          </Realm>
    
          <Host name="localhost"  appBase="webapps"
                unpackWARs="true" autoDeploy="true">
    
            
            
    
            
            <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
                   prefix="localhost_access_log" suffix=".txt"
                   pattern="%h %l %u %t "%r" %s %b" />
    
          </Host>
        </Engine>
      </Service>
    </Server>

## 3、部署web工程 ##

新建个一个web工程，我这里命名为session\_test, 主要就是web.xml和index.jsp文件，将工程分别部署到tomcat1-3里面. 为了区分各个tomcat服务器,index.jsp稍微不一样.

web.xml ：添加 了<distributable/>

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
      <display-name>session_test</display-name>
      <distributable/>  
      <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
      </welcome-file-list>
    
      <servlet>
        <description>This is the description of my J2EE component</description>
        <display-name>This is the display name of my J2EE component</display-name>
      
    </web-app>

index.jsp

<%@page language="java"%>
    <html>
    <body>
            <h1><font color="red">Session serviced by tomcat</font></h1>
            <table aligh="center" border="1">
                    <tr>
                            <td>Session ID</td>
                            <td><%=session.getId() %>-----tomcat1</td>
                            <% session.setAttribute("abc","abc");%>
                    </tr>
                    <tr>
                            <td>Created on</td>
                            <td><%= session.getCreationTime() %></td>
                    </tr>
            </table>
    </body>
    <html>

![20161008195048942][]

至此，所有配置和部署都完成了.

## 4、启动nginx和tomcat服务 ##

（1）启动nginx服务

打开命令行cmd,切换到nginx安装目录下，运行start nginx 启动服务.

![20161008195830632][]

注:停止nginx服务的命令是 nginx -s stop

(2) 分别启动tomcat1 、tomcat2、tomcat3服务.

直接双击tomcat 下的bin目录的startup.bat文件即可启动对应的tomcat服务.

##  5、测试负载均衡和session复制 ##

打开浏览器输入http://localhost/session\_test ，效果如下，表示访问的是tomcat3服务器

![20161008200715780][]

刷新浏览器，界面变换如下，表示访问的是tomcat1服务器.

![20161008200756636][]

由上面两幅图可以看出，nginx会把每次请求随机分配到不同的tomcat服务器，此为：负载均衡.

每次请求的sessionId值没有变化，表示session复制成功.

[Center]: /images/20220716/0c1d565193de4121ae4e1963e4646e05.png
[20161008195048942]: /images/20220716/bd4f211560374eb6bfb17597ccc3123b.png
[20161008195830632]: /images/20220716/70fb14b49c27428c952cdd403c60371a.png
[20161008200715780]: /images/20220716/377bd71cdf2f46baa0051bccf482a38a.png
[20161008200756636]: /images/20220716/65dfee7dbace4236ad62faf14ece7712.png