Global Terraform code

Stacks allows you to define global Terraform code that's shared across all stacks.

This can be used for use cases like defining a common Terraform state backend template (see this), or iterating through a list of regions to define multiple instances of the same provider (see this).

Global Terraform code must be located in the stacks directory like this:

|-- environments/
`-- stacks/
   |-- ...
   `-- global.tf   # here

Any files named *.tf will work.