Terraform as a backend (in a compiler sense)

Every time I’ve tried to use terraform proper I have failed. Fundamentally it is a non-composable tool so if you want compostionlity you have to work around its limitations. One way I’ve found to force compositionality is to not rely on any of its high level features. I only use it for managing resource graphs. That’s the only part I think it is good at and that’s the only part that consistently works. If you feed it a resource graph then it will mostly work. This means you’ll have to find some way to generate and feed it the resource graph. There are a few ways to do it and in the past I would have recommended ERB but there is actually a simpler way that just requires generating JSON. You could generate the JSON from anything you are comfortable with that provides the kind of compostionality you expect. I’m going to outline how I use Rake and Ruby to do this for a very basic VPC configuration across several regions and availability zones. Continue reading