Terraform staging environment

I was looking for a fairly simple way of handling different deployment environments with Terraform. Here are some of my notes on variables, workspaces, environments and variable overrides.

• Use workspaces to separate state files. This is important when using variable overrides to e.g. go from staging to testing by changing namespaces. Without a change of workspace, Terraform will think you want to destroy staging, then set up `testing, instead of having them side by side.
• All files that ends with .tf will be loaded and appended onto each other.
• Resources with the same name will raise validation errors.
• terraform.tfvars and any other files that ends with .auto.tfvars will be automatically loaded, overriding default variables.
• Other .tfvars files may be references when running commands, e.g. terraform plan -var-file=staging.tfvars

Variable files containing overrides (.tfvars) have a simple syntax:

gce_region = "europe-west1-c"
namespace = "myapp-staging"

References

• https://groups.google.com/forum/#!topic/terraform-tool/l6FGol0iXww
• https://www.terraform.io/docs/configuration/variables.html