Terraform provider/variable sharing in modules

Question

Is there a way of abstracting the provider for all the modules defined in a project.

for example, I have this project

├── modules │   ├── RDS │   └── VPC └── stacks     ├── production     │   └── main.tf     └── staging         └── main.tf 

and it works fine... the problem is with the definition of modules

├── RDS │   ├── README.md │   ├── main.tf │   ├── providers.tf │   └── variables.tf └── VPC     ├── README.md     ├── main.tf     ├── providers.tf     └── variables.tf 

the provider in both of these modules are exactly the same

# providers.tf provider "aws" {   region = "${var.region}"   version = "~> 1.26" } 

and the variables in each module are different but they all have the region variable.

# variables.tf variable "region" {   default     = "eu-central-1"   description = "AWS region." } # other module dependent variables... 

is there a way to define those bits of information on the modules level so that I end up with something roughly like this

├── modules │   ├── providers.tf  <<< include the *shared* provider definition block │   ├── variables.tf  <<< include the *shared* region vaiable definition block │   ├── RDS │   │   ├── README.md │   │   ├── main.tf │   │   └── variables.tf │   └── VPC │       ├── README.md │       ├── main.tf │       └── variables.tf 

one last thing, the modules definitions most of the time have a resource attribute (pulling a module from the terraform registry... therefore I don't know if it's feasible to inherit both the source from the registry and a base module)

Answer 1

Right now it's not possible to achieve that. There were previous discussions on github about the same topic in the following issues:

• https://github.com/hashicorp/terraform/issues/5480
• https://github.com/hashicorp/terraform/issues/4585
• https://github.com/hashicorp/terraform/issues/2714
• https://github.com/hashicorp/terraform/issues/1742
• https://github.com/hashicorp/terraform/issues/1478

TL;DR
the sharing of variables between modules is against terraform core clarity/explicity principles.

Workaround
A workaround is to have the *shared* files in the parent directory and using symlinks to add them to the modules.