Feature Request: Support Multiple Environment Deployments with Terraform

[Aghassi]

I've been trying to set this up for the last few days at our company, and I've found that this repo may need a major overhaul to accomplish this. We already have a prod environment, and I went down this road because I tried to setup a staging environment for testing. I've got a working PoC internally that I can base a PR on, but essentially here is what is necessary:

1. Terraform keeps state of the current directory. As such, adding a prefix will not change anything when deploying infrastructure. In fact, it will cause some of the resources to be destroyed and recreated. We don't want this at scale if I want to have both a staging and a prod environment. Nor do I want this if I want to do something like run a CI integration that vets I can always deploy a new version to an environment by creating a test environment and then tearing it down.
2. To solve for this, all resources need to be moved from circleci.tf to modules/ folder, with each subfolder having one module per resource grouping. So, the way I have organized it in my PoC is

modules
├── aws_alb
├── aws_sqs
├── iam_instances
├── legacy-builder
├── legacy-builder-cloudinit-ubuntu-docker-v1
├── nomad
├── nomad-cloudinit-ubuntu-v1
├── s3_bucket
├── services_machine
└── vm_machine

The reason for this is so I can accomplish the next step.

3. Make variables.tf, circleci.tf, terraform.tfvars, files/, and templates/ all "templates" so to speak. Add a section to the Makefile that would allow make environment staging for example. This would then copy all of the afformentioned files to a folder structure like:

environments
├── prod
└── staging

and the sub folder structure would look like

environments/staging
├── files
├── main.tf
├── templates
├── terraform.tfstate
├── terraform.tfstate.backup
├── terraform.tfvars
└── variables.tf

And so on. This allows for me as a consumer to run terraform init/terraform plan on any environment of my choosing in the same AWS infrastructure without colliding or breaking existing infrastructure.