How to know the reason why an environment turns RED health in Elastic Beanstalk?

This is an old question but for the sake of people coming to this website, here is an update. Elastic Beanstalk recently announced support for Enhanced Application health monitoring.

https://aws.amazon.com/blogs/aws/elastic-beanstalk-update-enhanced-application-health-monitoring/

Now along with a health color, you can also discover "causes" which is an english language description for why the health of an environment transition.

You can also read about enhanced health reporting here: http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/health-enhanced.html

AWS is pretty useless on health screen, it only shows "severe" on my screen, that`s it. I can see it on main screen too, I wonder why Amazon coders like to create pretty useless screens. If this happens during deploying your code, there is one reason for that, your instance t1.micro or t2.micro allocated and shared pretty small amount of resource. It looks like resources are not available during your deployment. If you are ready to pay, you will get your resources.