I added .ebextensions/start.config file to the root folder of my WAR bundle (as suggested by AWS), deployed it to Elastic Beanstalk, but nothing happened. Where
Snapshot the Logs for your Elastic Beanstalk environment through the online console.
When you view the logs, search for a section beginning "cfn-init.log".
In that section you'll see entries like
2013-08-30 10:25:13,517 [INFO] Command 01-ec2setcomputername-enable succeeded
2013-08-30 10:25:24,516 [INFO] Command 02-install-server-monitor succeeded
2013-08-30 10:25:30,115 [INFO] Command 03-install-agent succeeded
where 01-ec2setcomputername-enable, etc. are the names of the commands in my .config file. If the command fails, you should see the error message here too.