Terraform structure and an empty example.

terraform/README.md

+# Terraform modules
+
+This directory contains Terraform modules and a library of reusable modules
+under `library`. Each module deploys a complete service. Although services will
+be interconnected and there will be dependencies between services, the goal is
+to keep the modules whole so that applying the module deploys the entire
+service.
+
+## A word on environments
+
+Each module has a Terraform variables files (`.tfvars`) and a workspace for each
+environment that service is deployed to. This puts the emphasis on keeping the
+services the same across different environments with little changes, mainly for
+scale (eg. 2 instances instead of 5).
+
+## Common workflow
+
+In this example, deploying to the dev environment. A convention is used for the
+default workflow (have it be prod or dev or just not used).
+
+```
+terraform init
+terraform workspace new dev
+# Or if the workspace is already present:
+terraform workspace select dev
+terraform plan -var-file=dev.tfvars -out=tfplan
+# Review the changes to be applied.
+terraform apply tfplan
+```
+
+## Some more information here (like different providers, other conventions)

terraform/foo/dev.tf

+instance_count = 2

terraform/foo/main.tf

+terraform {
+  backend "s3" {
+    bucket         = "tf-states"
+    key            = "foo.tfstate"
+    region         = "us-east-1"
+    encrypt        = true
+    dynamodb_table = "tf-locks"
+  }
+}
+
+locals {
+  env    = terraform.workspace == "default" ? "prod" : terraform.workspace
+  module = basename(abspath(path.root))
+}

terraform/foo/providers.tf

+provider "aws" {
+  default_tags {
+    tags = {
+      Environment = local.env
+      # Easy to track down which module created a resource.
+      Module      = local.module
+    }
+  }
+}

terraform/foo/staging.tf

+instance_count = 3

terraform/foo/variables.tf

+variable "instance_count" {
+  type        = number
+  description = "The number of instances to deploy."
+  # If the convention is not to use the default workspace, delete the default
+  # value.
+  default     = 5
+}

terraform/library/README.md

+# Terraform module library
+
+A library of reusable modules (not to deployed by themselves).

terraform/library/aws/asg/README.md

+# Auto scaling group