为了获取更好的性能，我们常常需要将tomcat进行集群部署。下文通过nginx转发实现tomcat集群，并通过nginx-upstream-jvm-route插件保证session的粘滞。
应用场景环境：
server1 服务器上安装了 nginx + tomcat01
server2 服务器上只安装了 tomcat02
server1 IP 地址： 192.168.1.88
server2 IP 地址： 192.168.1.89
安装步骤：
1）在server1 上安装配置 nginx + nginx_upstream_jvm_route
shell $> wget -c http://sysoev.ru/nginx/nginx-*.tar.gz
shell $> svn checkout http://nginx-upstream-jvm-/svn/trunk/ nginx-upstream-jvm-route-read-only
shell $> tar zxvf nginx-*
shell $> cd nginx-*
shell $> patch -p0 < ../nginx-upstream-jvm-route-read-only/jvm_route.patch
shell $> useradd www
shell $> ./configure --user=www --group=www --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module --add-module=/root/nginx-upstream-jvm-route-read-only
shell $> make
shell $> make install
2）分别在两台机器上安装 tomcat和java
设置tomcat的server.xml，在两台服务器的tomcat的配置文件中分别找到：
<Engine name="Catalina" defaultHost="localhost" >
分别修改为：
Tomcat01:
<Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
Tomcat02:
<Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm2">
分别启动两个tomcat
3）设置nginx
shell $> cd /usr/local/nginx/conf
shell $> mv nginx.conf nginx.bak
shell $> vi nginx.conf
配置示例：
worker_processes 4;error_log logs/nginx_error.log crit;pid /usr/local/nginx/nginx.pid;#Specifies the value for maximum file descriptors that can be opened by this process.worker_rlimit_nofile 51200;events{use epoll;worker_connections 2048;}http{upstream backend {server 192.168.1.88:8080 srun_id=jvm1;server 192.168.1.89:8080 srun_id=jvm2;jvm_route $cookie_JSESSIONID|sessionid reverse;}include mime.types;default_type application/octet-stream;#charset gb2312;charset UTF-8;server_names_hash_bucket_size 128;client_header_buffer_size 32k;large_client_header_buffers 4 32k;client_max_body_size 20m;limit_rate 1024k;sendfile on;tcp_nopushon;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_buffers4 16k;gzip_http_version 1.0;gzip_comp_level 2;gzip_types text/plain application/x-javascript text/css application/xml;gzip_vary on;#limit_zone crawler $binary_remote_addr 10m;server{listen 80;server_name 192.168.1.88;ssi on; ssi_silent_errors on; ssi_types text/shtml; index index.html index.htm index.jsp;root /var/www;#location ~ .*\.jsp$location /app/{proxy_pass http://backend;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 $http_host;}location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)${expires30d;}location ~ .*\.(js|css)?${expires1h;}location /Nginxstatus {stub_status on;access_log off;}log_format access '$remote_addr - $remote_user [$time_local] "$request" ''$status $body_bytes_sent "$http_referer" ''"$http_user_agent" $http_x_forwarded_for';# access_log off;}}
4）测试
运行 nginx -t 测试配置的正确性，
可将服务器注释一个，实现服务的热部署，
server 192.168.2.88:8080 srun_id=jvm1;
server 192.168.2.89:8080 srun_id=jvm2;
运行 nginx -s reload 实现热部署。
