In the dynamic world of cloud infrastructure, maintaining the desired state of your resources is crucial. Terraform, a powerful Infrastructure as Code (IaC) tool, helps manage your infrastructure declaratively. However, changes made outside of Terraform can cause “drift,” where the actual state of resources diverges from the expected state. Detecting and managing drift is essential for maintaining infrastructure reliability and consistency. In this post, we’ll explore how to detect drift in Terraform-managed infrastructure and discuss alternatives like env0 for enterprise Terraform management. We’ll also touch on how these concepts apply to OpenTofu (formerly known as Terraform Community Edition).

Understanding Drift Detection

Drift detection in Terraform involves comparing the current state of your infrastructure against the state defined in your Terraform configuration. By running terraform plan, you can identify any discrepancies or changes that have occurred outside of Terraform’s management.

Automating Drift Detection with GitHub Actions

To ensure continuous monitoring, we can automate drift detection using GitHub Actions. Below is a script that runs daily to check for drift in your Terraform-managed infrastructure.

GitHub Actions Script for Drift Detection

name: Check Terraform Drift

on:
  schedule:
    - cron: '0 0 * * *' # Runs daily at midnight

jobs:
  terraform:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Terraform
        uses: hashicorp/setup-terraform@v1

      - name: Terraform Init
        run: terraform init
        # run: tofu init (for OpenTofu)

      - name: Terraform Plan
        id: plan
        run: terraform plan
        # run: tofu plan (for OpenTofu)

      - name: Check for drift
        run: |
          if ! grep -q "No changes. Infrastructure is up-to-date." <<< "$"; then
            echo "Drift detected! Please check the plan output."
            exit 1
          else
            echo "No drift detected."
          fi

This script performs the following steps:

  1. Schedules the Job: Runs daily at midnight.
  2. Checks Out the Code: Retrieves your Terraform configuration from your repository.
  3. Sets Up Terraform: Initializes the Terraform environment.
  4. Runs Terraform Init: Initializes the Terraform working directory.
  5. Runs Terraform Plan: Creates an execution plan, showing any changes required to reach the desired state.
  6. Checks for Drift: Parses the plan output to detect drift and exits with an error if drift is found.

Using OpenTofu

For those using OpenTofu, the commands remain largely the same, with minor adjustments to the commands (tofu init and tofu plan).

Alternatives for Enterprise Terraform Management

env0

For enterprises seeking a more robust solution for managing Terraform at scale, env0 offers advanced capabilities such as:

  • Automated Drift Detection: env0 automatically detects drift across your environments, providing notifications and detailed reports.
  • Collaboration Tools: Facilitates teamwork by providing visibility into infrastructure changes and deployments.
  • Policy Enforcement: Integrates policy checks to ensure compliance with organizational standards before changes are applied.
  • Cost Management: Helps track and manage cloud costs associated with Terraform-managed resources.

How env0 Works

env0 integrates with your version control system (VCS) and continuously monitors your infrastructure. It provides a dashboard to view drift, manage deployments, and enforce policies. When drift is detected, env0 can automatically trigger remediation workflows or notify the relevant teams to take action.

OpenTofu and Enterprise Solutions

OpenTofu (formerly known as Terraform Community Edition) supports the same core functionalities as Terraform. For enterprise solutions, tools like env0 are compatible with OpenTofu, offering similar benefits for drift detection, collaboration, and policy enforcement.

Conclusion

Ensuring that your infrastructure remains consistent with your Terraform configuration is vital for maintaining reliability and security. Automated drift detection using tools like GitHub Actions can help maintain this consistency. For larger organizations, solutions like env0 provide comprehensive enterprise features to manage Terraform and OpenTofu environments effectively. By implementing these practices, you can keep your infrastructure in sync and minimize the risks associated with configuration drift.

Next Steps

  • Implement the GitHub Actions Script: Set up the provided script in your repository to start monitoring drift.
  • Explore env0: Consider using env0 for advanced drift detection and management features in enterprise environments.
  • Stay Updated: Regularly update your Terraform or OpenTofu configurations and automation scripts to adapt to new features and best practices.