title: terraform validate error: The argument "region" is required, but was not set
body: <p>I wrote a custom <code>RDS</code> module for my development team to consume for deploying <code>RDS</code> instances. I am using <code>BitBucket</code> for source control and I am trying to integrate a <code>BitBucket</code> pipeline to run <code>terraform validate</code> on my <code>.tf</code> files to validate syntax before making it consumable to the devs.<code>terraform init</code> runs fine but when I run <code>terraform validate</code> I get the following error: <code>Error: Missing required argument. The argument "region" is required, but was not set.</code> After looking at the documentation, I am confused why this command would check for a declared provider if it is not actually deploying anything? I am admittedly new to writing modules. Perhaps this isn't the right command for what I want to accomplish?</p>
  
  <p><code>Terraform version:</code> <strong>v0.12.7</strong></p>
  
  <p><code>AWS Provider version:</code> <strong>2.24</strong></p>
  
  <p><code>bitbucket-pipelines.yml:</code></p>
  
  <pre><code>image: hashicorp/terraform:full
  
  pipelines:
    branches:
      master:
      - step:
          script:
            - terraform version
            - terraform init
            - terraform validate
  </code></pre>
  
  <p><code>Module tree:</code></p>
  
  <pre><code>├── CHANGELOG.md
  ├── README.md
  ├── bitbucket-pipelines.yml
  ├── main.tf
  ├── modules
  │   ├── db_instance
  │   │   ├── README.md
  │   │   ├── main.tf
  │   │   ├── outputs.tf
  │   │   └── variables.tf
  │   ├── db_option_group
  │   │   ├── README.md
  │   │   ├── main.tf
  │   │   ├── outputs.tf
  │   │   └── variables.tf
  │   ├── db_parameter_group
  │   │   ├── README.md
  │   │   ├── main.tf
  │   │   ├── outputs.tf
  │   │   └── variables.tf
  │   └── db_subnet_group
  │       ├── README.md
  │       ├── main.tf
  │       ├── outputs.tf
  │       └── variables.tf
  ├── outputs.tf
  └── variables.tf
  </code></pre>