nginx_upstream_jvm_route 实验
基础知识：
这个模块通过session cookie的方式来获取session粘性。如果在cookie和url中并没有session，则这只是个简单的round-robin 负载均衡。
jvm_route的原理(from 作者 Weibin Yao)：
1. 一开始请求过来，没有带session信息，jvm_route就根据round robin的方法，发到一台tomcat上面。
2. tomcat添加上session 信息，并返回给客户。
3. 用户再此请求，jvm_route看到session中有后端服务器的名称，它就把请求转到对应的服务器上。
暂时jvm_route模块还不支持默认fair的模式。jvm_route的工作模式和fair是冲突的。对于某个特定用户，当一直为他服务的tomcat宕机后，默认情况下它会重试max_fails的次数，如果还是失败，就重新启用round robin的方式，而这种情况下就会导致用户的session丢失。
总的说来，jvm_route是通过session_cookie这种方式来实现session粘性，将特定会话附属到特定tomcat上,从而解决session不同步问题，但无法解决宕机后会话转移问题。
Jvm_route实验部分：
准备工作：
1.下载apache-tomcat，分别安装到~/apache-tomcat00，~/apache-tomcat01目录下。
2.下载nginx-0.7.65
3.下载nginx-upstream-jvm-route
wget http://nginx-upstream-jvm-route.googlecode.com/files/nginx-upstream-jvm-route-0.1.tar.gz
安装：
进入到nginx-0.7.65安装目录：
#patch –p0 < /path/to/jvm_route.patch
编译安装nginx
#./configure --prefix=/path/to/install/ --with-http_stub_status_module --with-http_ssl_module –add-module=/path/to/jvm_route/
#make
#make install
修改配置：
1. 修改apache-tomcat00/conf/server.xml配置:
修改端口号，避免冲突：
2. 参照1，修改apache-tomcat01
3.分别启动apache-tomcat00，apache-tomcat01
4. nginx配置如下：
user liuxiaoqin liuxiaoqin;
worker_processes 2;
#error_log logs/error.log;
#error_log logs/error.log notice;
error_log logs/error.log info;
pid logs/nginx.pid;
events {
use epoll;
worker_connections 1024;
}
http {
upstream newtomcat {
#ip_hash;
server 127.0.0.1:8080 max_fails=3 fail_timeout=30s srun_id=a;
server 127.0.0.1:8081 max_fails=3 fail_timeout=30s srun_id=b;
jvm_route $cookie_JSESSIONID|sessionid reverse;
}
include mime.types;
default_type application/octet-stream;
log_format access '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" $http_x_forwarded_for';
#log_format main '$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 access;
sendfile on;
tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
#gzip on;
server {
listen 80;
server_name localhost;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm;
}
location /aa/{
proxy_pass http://newtomcat;
proxy_redirect off;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $http_host;
}
location /bb/{
proxy_pass http://newtomcat;
proxy_redirect off;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $http_host;
}
location /Nginxstatus {
stub_status on;
access_log off;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# 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 ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
# ssl_prefer_server_ciphers on;
# location / {
# root html;
# index index.html index.htm;
# }
#}
5.在apache-tomcat00目录/webapps/,
mkdir aa;
创建文件index.jsp.内容如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
a
<%out.print(request.getSession()) ;%>
<%out.println(request.getHeader("Cookie")); %>
6.在apache-tomcat01目录下/webapps/,
mkdir bb;
创建文件index.jsp.内容如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
b
<%out.print(request.getSession()) ;%>
<%out.println(request.getHeader("Cookie")); %>
这样，我们在浏览器中输入127.0.0.1/aa/就可以看到输出， 并且可以观察到无论刷新多少次，输出结果不变。