Automating Terraform with Version Control: Triggering Plan and Apply

In modern DevOps practices, automation is key to achieving efficiency, consistency, and reliability. When it comes to managing infrastructure as code (IaC) with Terraform, integrating it with version control systems (VCS) like GitHub, GitLab, or Bitbucket can take your workflows to the next level.

By triggering the Terraform plan and applying operations automatically through version control, you can ensure that infrastructure changes are reviewed, tested, and deployed consistently. In this article, we’ll explore how to set up version control-based triggering for Terraform and the benefits it brings to your workflow.

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Why Use Version Control with Terraform?

Integrating Terraform with version control offers several advantages:

1. Collaboration: Multiple team members can work on the same infrastructure code.

2. Code Reviews: Changes can be reviewed and approved through pull requests (PRs).

3. Audit Trail: Every change is tracked, providing a clear history of who made what changes and why.

4. Automation: Automate Terraform operations (plan, apply) based on VCS events like PRs or merges.

5. Consistency: Ensure that infrastructure changes are applied consistently across environments.

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How to Set Up Version Control-Based Triggering

Let’s walk through the steps to set up version control-based triggering for Terraform using GitHub and Terraform Cloud.

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Step 1: Set Up Terraform Cloud

1. Create a Terraform Cloud Account: Sign up at Terraform Cloud.

2. Create an Organization: Set up an organization for your team.

3. Create a Workspace: Create a workspace linked to your VCS repository.

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Step 2: Connect Terraform Cloud to GitHub

1. Configure VCS Integration:

   • Go to your Terraform Cloud organization settings.

   • Under Version Control, connect your GitHub account.

   • Authorize Terraform Cloud to access your repositories.

2. Link Your Repository:

   • In your Terraform Cloud workspace, select Version Control as the workflow mode.

   • Choose the repository containing your Terraform configuration.

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Step 3: Configure GitHub Actions (Optional)

If you’re not using Terraform Cloud, you can use GitHub Actions to automate Terraform operations. Here’s an example workflow:

.github/workflows/terraform.yml

name: Terraform Plan and Apply

on:
  pull_request:
    branches:
      - main
  push:
    branches:
      - main

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

      - name: Terraform Plan
        run: terraform plan
        if: github.event_name == 'pull_request'

      - name: Terraform Apply
        run: terraform apply -auto-approve
        if: github.event_name == 'push'

This workflow:

• Runs terraform plan on pull requests to the main branch.

• Runs terraform apply on pushes to the main branch.

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Step 4: Use Pull Requests for Collaboration

1. Create a Feature Branch:

   • Create a new branch for your infrastructure changes.

   • Make changes to your Terraform configuration files.

2. Open a Pull Request:

   • Push your changes to the feature branch and open a PR.

   • Terraform Cloud or GitHub Actions will automatically run terraform plan and post the results in the PR.

3. Review and Merge:

   • Review the terraform plan output to ensure the changes are as expected.

   • Once approved, merge the PR into the main branch.

   • Terraform Cloud or GitHub Actions will automatically run terraform apply.

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Benefits of Version Control-Based Triggering

1. Automated Workflows: Reduce manual steps and human errors by automating Terraform operations.

2. Improved Collaboration: Enable team members to review and approve changes through PRs.

3. Enhanced Security: Ensure that changes are reviewed and tested before being applied.

4. Audit Trail: Track all changes and approvals in your version control system.

5. Consistency: Apply changes consistently across environments using the same workflow.

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Best Practices for Version Control with Terraform

1. Use Separate Workspaces for Environments:

   • Create separate Terraform workspaces for dev, staging, and production environments.

   • Use version control to manage changes across environments.

2. Leverage Branching Strategies:

   • Use feature branches for new changes and PRs for reviews.

   • Protect the main branch to prevent direct pushes.

3. Automate Testing:

   • Use tools like Terratest to write automated tests for your Terraform configurations.

   • Integrate testing into your CI/CD pipeline.

4. Monitor and Alert:

   • Set up monitoring and alerts for your Terraform runs.

   • Use Terraform Cloud’s Sentinel policies to enforce compliance and governance.

5. Document Your Workflow:

   • Document your version control and Terraform workflow for your team.

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Real-World Use Cases

Here are some examples of how version control-based triggering can be used:

• Infrastructure Changes: Automate the deployment of new resources or updates to existing ones.

• Environment Promotion: Promote changes from dev to staging to production using PRs and automated workflows.

• Compliance and Governance: Use Sentinel policies in Terraform Cloud to enforce compliance rules.

• Disaster Recovery: Quickly recreate infrastructure from version-controlled configurations.

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Conclusion

Integrating Terraform with version control systems like GitHub, GitLab, or Bitbucket is a game-changer for managing infrastructure as code. By automating Terraform plan and apply operations through version control, you can improve collaboration, ensure consistency, and reduce manual effort.

Whether you’re using Terraform Cloud, GitHub Actions, or another CI/CD tool, version control-based triggering is a must-have for modern infrastructure workflows.

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