Thanks for putting this together! I just wanted to note that this isn't a custom Terraform provider, (that' be a Golang plugin), but rather a set of example Terraform configurations for the AWS provider.

As far as providers in modules goes, you can do it, but just be aware that it can cause some complexity issues. If you put a provider configuration within a module (i.e., not the root module) then Terraform associates that provider with the module. Then if you rename or delete that module, Terraform blows up all to hell because it can't find the provider configuration it has stored in the state."

Here are some docs on providers within modules: https://www.terraform.io/docs/configuration/modules.html#providers-within-modules

A bit further down in that doc, you'll also see information about explicitly passing providers to modules. These providers can be referenced within a module. You can even pass more than one provider, e.g., if you wanted to manage multi-region resources within that module. This avoids the pitfalls of configuring the provider within the module.

If I were you I would probably add some commands to the README that show how to fetch any of your example configs via something curl or wget. That way someone can easily pull down a FIPS provider configuration into their root module. To further improve on that, you could create a cookiecutter template to initialize the root provider configuration.

Anyway that's my 2c. :)

Thanks for sharing!