Mastering terraform_remote_state: Securely Accessing Outputs Across Configurations

In a world where infrastructure is code, sharing outputs between different Terraform configurations is crucial. The terraform_remote_state data source allows you to retrieve root module output values from a specified state backend, solving the problem of inter-module communication. This is particularly useful when you have separate configurations for different parts of your infrastructure, like networking and application layers, and you need to reference outputs from one in another.

How does it work? The terraform_remote_state data source connects to a specified backend to fetch the latest state snapshot. It doesn't require a separate provider configuration since it's built into Terraform itself. You'll need to specify the backend and, optionally, the workspace and configuration settings. For example, you can access outputs from a remote backend like this:

data "terraform_remote_state" "vpc" { backend = "remote" config = { organization = "hashicorp" workspaces = { name = "vpc-prod" } } }

In production, you need to be cautious. While terraform_remote_state is powerful, it exposes the entire state snapshot to anyone with access to the outputs. This means if your configuration deals with sensitive data, you should avoid using it. Instead, consider the tfe_outputs data source for HCP Terraform or Terraform Enterprise, as it provides a more secure way to access outputs without exposing the full state. Always evaluate the security implications before implementing this in your infrastructure.