title: Custom resource for existing Terraform provider?
body: <p>I've been playing around with writing a custom resource for AWS which combines other resources in a useful way. (It's too complex to achieve effectively with a Terraform module.)</p>
  
  <p>The documentation (starting with the <a href="https://www.terraform.io/docs/plugins/provider.html" rel="nofollow noreferrer">Plugins page</a>) outlines how to create a completely new resource from scratch. However, is it possible to "attach" my custom resource to the AWS provider? This would allow me to:</p>
  
  <ul>
  <li>name my resources e.g. <code>aws_foo</code> instead of <code>awscontrib_foo</code></li>
  <li>presumably, access AWS credentials already defined for that provider</li>
  </ul>