Better module support

[kddejong]

We've done a lot of work to not fail a template bases on Modules. However there are a lot of things we can do to build out better support.

Reading the registry to determine the parameters and resource types. This allows us to validate naming conflicts, Ref/GetAtt relationships, if a module parameter is being used by a condition which means you can't ref/getatt that value, limits, etc.

Some of the big work to be done include:

• We need to support the Registry schema for the rules describe above.
• We need to download the registry schema from a users account/region. This would include us needing to have credentials to get these files. Today cfn-lint doesn't require credentials and was completely designed to be offline validation. However with Registry Resource Types and Modules we need to think about starting being able to query an account inside cfn-lint.

[PatMyron]

We need to download the registry schema from a users account/region. This would include us needing to have credentials to get these files. Today cfn-lint doesn't require credentials and was completely designed to be offline validation. However with Registry Resource Types and Modules we need to think about starting being able to query an account inside cfn-lint.

Was thinking we could provide a script that could be run separately and allow the output to be passed in similar to https://github.com/aws-cloudformation/cfn-python-lint/pull/1732

[miparnisari]

However with Registry Resource Types and Modules we need to think about starting being able to query an account inside cfn-lint.

+1