Move current terraform into a GCP specific module

[yuvipanda]

We will use completely different terraform code for each cloud provider,
under terraform/<cloud-provider>. This is much simpler than trying to abstract
them away into a 'lowest common denominator' set of modules.

Ref #512

[yuvipanda]

Would love to know what you think of this, @consideRatio @damianavila @sgibson91 @GeorgianaElena

[sgibson91]

This is similar to what I was thinking about over lunch. Each cloud provider we deploy to via terraform has it's own submodule, and we have a top-level variable like cloud_provider that we use in some logic to import the correct module when doing a terraform plan/apply. It means more code to maintain, but as of yet I don't know of a more elegant solution and terraform isn't a truly cloud-agnostic tool (it's dependent on the provider).

[yuvipanda]

Each cloud provider we deploy to via terraform has it's own submodule, and we have a top-level variable like cloud_provider that we use in some logic to import the correct module when doing a terraform plan/apply.

I tried this, and unfortunately you can't use a variable to specify which module to load in terraform :(

[sgibson91]

Boo! :( In which case, I think this solution is good enough.

[consideRatio]

I wonder if @andersy005 or @cmd-ntrf with significant experience with terraform could comment about this for us? Anderson and Félix, do you think it is a reasonable approach to have separate terraform code for deploying infrastructure to separate cloud providers?

[damianavila]

I think this is a sensible proposal. Since terraform is not agnostic from the cloud provider I think any attempt to make that happen will look-like weird and, most likely, difficult if not impossible to do it in a sane way. But, hey, I do not have a lot of experience with terraform and I might be missing something...

[consideRatio]

This LGTM from what I can tell and feel comfortable relying on @yuvipanda's judgement given that it has been explicit deliberation on the decision regarding making room for separate terraform code for different cloud providers.

I went ahead and made some off topic adjustments to the URLs 🙉

[damianavila]

As I said in the specific comment, I think this is a sensible idea.

[yuvipanda]

I think this has enough approval to be merged?

[yuvipanda]

@sgibson91 this might require you to rebase some of the terraform code you are working on wrt private clusters