Module templates

ProviderName
    └── ModuleName
            ├── main.tf
            ├── outputs.tf
            ├── README.md
            └── variables.tf

The list of Providers for Terraform can be found here: https://registry.terraform.io/browse/providers

main.tf : Call modules, locals and data-sources to create all resources
variables.tf : Contains declarations of variables used in main.tf
outputs.tf : Contains outputs from the resources created in main.tf

Do not use a locals.tf in the modules.
Only use that in the environment directory and then pass those as variables to the modules.