Arun Gupta, Miles to go ...

TOTD #81: How to use nginx to load balance a cluster of GlassFish Gem ?

nginx (pronounced as "engine-ex") is an open-source and high-performance HTTP server. It provides the common features such as reverse proxying with caching, load balancing, modular architecture using filters (gzipping, chunked responses, etc), virtual servers, flexible configuration and much more.

1. Download, build, and install nginx using the simple script (borrowed from dzone):
   
   

   ~/tools > curl -L -O http://sysoev.ru/nginx/nginx-0.6.36.tar.gz ~/tools > tar -xzf nginx-0.6.36.tar.gz ~/tools > curl -L -O http://downloads.sourceforge.net/pcre/pcre-7.7.tar.gz ~/tools > tar -xzf pcre-7.7.tar.gz ~/tools/nginx-0.6.36 > ./configure --prefix=/usr/local/nginx --sbin-path=/usr/sbin --with-debug --with-http_ssl_module --with-pcre=../pcre-7.7 ~/tools/nginx-0.6.36 > make ~/tools/nginx-0.6.36 > sudo make install ~/tools/nginx-0.6.36 > which nginx /usr/sbin/nginx

   
   OK, nginx is now roaring and can be verified by visiting "http://localhost" as shown below:
   
   
   
2. Create a simple Rails scaffold as:
   
   

   ~/samples/jruby >~/tools/jruby/bin/jruby -S rails runner ~/samples/jruby/runner >~/tools/jruby/bin/jruby script/generate scaffold runlog miles:float minutes:integer ~/samples/jruby/runner >sed s/'adapter: sqlite3'/'adapter: jdbcsqlite3'/ <config/database.yml >config/database.yml.new ~/samples/jruby/runner >mv config/database.yml.new config/database.yml ~/samples/jruby/runner >~/tools/jruby/bin/jruby -S rake db:migrate

3. Run this application using GlassFish Gem on 3 separate ports as:
   
   

   ~/samples/jruby/runner >~/tools/jruby/bin/jruby -S glassfish Starting GlassFish server at: 192.168.1.145:3000 in development environment... Writing log messages to: /Users/arungupta/samples/jruby/runner/log/development.log. Press Ctrl+C to stop.

   
   The default port is 3000. Start the seond one by explicitly specifying the port using "-p" option ..
   
   

   ~/samples/jruby/runner >~/tools/jruby/bin/jruby -S glassfish -p 3001 Starting GlassFish server at: 192.168.1.145:3001 in development environment... Writing log messages to: /Users/arungupta/samples/jruby/runner/log/development.log. Press Ctrl+C to stop.

   
   and the last one on 3002 port ...
   
   

   ~/samples/jruby/runner >~/tools/jruby/bin/jruby -S glassfish -p 3002 Starting GlassFish server at: 192.168.1.145:3002 in development environment... Writing log messages to: /Users/arungupta/samples/jruby/runner/log/development.log. Press Ctrl+C to stop.

   
   On Solaris and Linux, you can run GlassFish as a daemon as well.
4. Nginx currently uses a simple round-robin algorithm. Other load balancers such as nginx-upstream-fair (fair proxy) and nginx-ey-balancer (maximum connections) are also available. The built-in algorithm will be used for this blog. Edit "/usr/local/nginx/conf/nginx.conf" to specify an upstream module which provides load balancing:
1. Create a cluster definition by adding an upstream module (configuration details) right before the "server" module:
   
   

   upstream glassfish {         server 127.0.0.1:3000;         server 127.0.0.1:3001;         server 127.0.0.1:3002;     }

   
   The cluster specifies a bunch of GlassFish Gem instances running at the backend. Each server can be weighted differently as explained here. The port numbers must exactly match as those specified at the start up. The modified "nginx.conf" looks like:
   
   
   
   The changes are highlighted on lines #35 through #39.
2. Configure load balancing by specifying this cluster using "proxy_pass" directive as shown below:
   
   

   proxy_pass http://glassfish;

   
   in the "location" module. The updated "nginx.conf" looks like:
   
   
   
   The change is highlighted on line #52.
   
5. Restart nginx by using the following commands:
   
   

   sudo kill -15 `cat /usr/local/nginx/logs/nginx.pid` sudo nginx

• nginx Website
• nginx Forum (very useful)
• nginx Wiki
• IRC #nginx

Posted by Arun Gupta in web2.0  |  Comments[8]