How to link Web App and MongoDB on AWS? Create separate amazon template cloudformation or install on server? Do both work?

How do I link Web App and MongoDB on AWS?

I see 2 options: Create separate amazon template cloud formation or install on server? Do both work?

I have it running locally with MongoDB on my C Drive as a data/db and MongoDB/bin/mongod.exe sort of setup. What is the best way of getting this linked in the cloud?