Terraform Remote State

When using Terraform, I find that storing state remotely has great benefits. If you work with others or on multiple machines, remote state allows re-using Terraform defined infrastructure without copying the state manually to all other users. More importantly, it allows a “core” set of resources to be defined and owned by one project while the root level output resources are re-usable in other related Terraform projects.

To store state remotely, add a backend to store the state such as:

terraform {
  backend "s3" {
    bucket = "<your bucket name>"
    key = "default"
    region = "us-east-1"
  }
}

Then you need to run terraform init after adding the backend to your Terraform config.

To import remote state (say you have a core infrastructure Terraform project), add another resource to import:

data "terraform_remote_state" "core_infrastructure" {
  backend = "s3"
  workspace = "${terraform.workspace}"
  config {
    bucket = "<bucket with state to import>"
    key = "default"
    region = "us-east-1"
  }
}

The core infrastructure that I generally have are definitions for DNS zones (so related projects can import the DNS managed zone identifier and create subdomains), wildcard SSL certificates for test domains, and general repository definitions for where the code is stored.

If you have multiple users, you will need to look into remote state locking solutions as well with your backends,