I have my MongoDB deployed in an EC2 instance, nice and steady. I will (hopefully) have my Elastic Beanstalk load-balanced Web App launched soon using Docker. However, I feel like my Database is too sensitive to dockerize or beastalk-ize, so I wanna keep it in a plain EC2 instance.
My issue is with regard to the security groups. How can I create a security group that will only accept MongoDB traffic (port 27017) from the Elastic Beanstalk? Since EC2 instances will get created and destroyed arbitrarily, maybe I can get the least-common subnet of those?