I want to use cloudformation to automatically join new instances to AD.
When I googled this it looks like many people just use scripts in there cloudformation templates and pass in credentials- I don't want to do that.
This article shows how this is seamless if you have the AWS Directory setup.
I already have an AD Domain setup with my own DCs, can I just use the AD Connector or something so I can seamlessly join new instances to that like I can with the AWS Directory Service?
AD Connector is a proxy for redirecting directory requests to your existing MSAD without caching any information on AWS. I've only ever used it for user authentication and I'd be curious to know if it'll work to join new instances to the directory.
Next step would be to follow the steps as outlined on https://docs.aws.amazon.com/directoryservice/latest/admin-guide/join_linux_instance.html to join the instances manually adding that information into the Userdata when deploying the server.
Of course, you'd need to set in the appropriate IAM Role.