You can do this using the AWS library or cli tools, combine that with Ansible etc and it works nice. Also, have you checked out Netflix for all their open source tools for AWS? They have a couple that dig into AWS and inventory what you have and allow you to make changes etc.
IIRC, Ansible has an inventory command, you just have to run it per AZ. I don't do the Ansible work everyday so it may be slightly different now.
For our configuration we use Ansible alone with the AWS API library and cli tools. So for example, we have backups scripted via cli tools and shell scripts but those scripts are configured and deployed using Ansible. In other places we have tools deployed via Ansible that use the Node API into AWS to get more information and make some minor setting changes.