Menttor
Library
LibraryAutomated `terraform apply` for specific branches or tags

Automated `terraform apply` for specific branches or tags

Learn about Automated `terraform apply` for specific branches or tags as part of Terraform Infrastructure as Code Mastery

Table of Contents

Automating Terraform Apply for Specific Branches and Tags

Leveraging Infrastructure as Code (IaC) with Terraform is powerful, but automating its deployment based on your Git workflow can significantly enhance efficiency and reduce manual errors. This module explores how to configure your CI/CD pipelines to automatically run

code
terraform apply
for specific branches or tags, ensuring your infrastructure changes are deployed predictably and reliably.

Why Automate `terraform apply`?

Automating

code
terraform apply
based on Git events offers several key benefits:

  • Consistency: Ensures that infrastructure changes are applied in a standardized manner.
  • Speed: Reduces the time between code commit and infrastructure deployment.
  • Reduced Errors: Minimizes human error associated with manual execution.
  • Traceability: Links infrastructure changes directly to specific Git commits, branches, or tags.
  • Controlled Rollouts: Allows for staged deployments, such as applying changes only to a staging environment from a
    code
    develop
    branch and to production from a
    code
    main
    or
    code
    release
    tag.

Branch-Based Deployments

A common strategy is to tie infrastructure deployments to specific branches. For instance:

  • code
    develop
    branch:     Might trigger
    code
    terraform apply
    to a staging or development environment.
  • code
    main
    or
    code
    master
    branch:     Could trigger
    code
    terraform apply
    to a production environment.
  • Feature branches: May trigger
    code
    terraform plan
    for review but not
    code
    terraform apply
    .

CI/CD pipelines can detect branch changes to trigger Terraform.

CI/CD platforms like GitLab CI, GitHub Actions, or Jenkins can be configured to monitor Git repository events. When a push occurs to a specific branch (e.g., develop), a predefined job can be executed. This job typically involves checking out the code, initializing Terraform, and then running terraform apply.

The core of this automation lies in the CI/CD pipeline configuration. For example, in GitHub Actions, you might define a workflow that triggers on push events to the develop branch. Within this workflow, a step would execute terraform apply. It's crucial to manage Terraform state securely and ensure that the pipeline runner has the necessary permissions and context to interact with your cloud provider.

Tag-Based Deployments

Tag-based deployments are often used for releasing specific, stable versions of your infrastructure. This is particularly useful for production environments where you want to deploy a known, tested state.

Git tags can signal production-ready infrastructure deployments.

When a Git tag is created (e.g., v1.2.0), CI/CD pipelines can detect this event. A job can then be configured to run terraform apply using the code associated with that tag, effectively deploying a specific version of your infrastructure. This provides a clear audit trail for production releases.

Tagging is a robust way to manage releases. A common pattern is to create a release branch from main, tag it (e.g., v1.0.0), and then have the CI/CD pipeline trigger terraform apply for the production environment based on that tag. This ensures that only explicitly versioned infrastructure states are deployed to production, offering a high degree of control and rollback capability.

Conditional Execution in CI/CD

Most CI/CD platforms allow you to define conditions for when jobs should run. This is essential for implementing branch and tag-based strategies.

CI/CD PlatformBranch/Tag Trigger Syntax (Example)
GitHub Actionson: push: branches: [ develop ] tags: [ 'v*' ]
GitLab CIonly: branches: - develop tags: - v*
JenkinsPipeline syntax with 'when' conditions based on SCM branch/tag

Best Practices and Considerations

When implementing automated

code
terraform apply
for branches and tags, consider the following:

  • State Management: Ensure your Terraform state file is stored remotely and securely (e.g., S3, Azure Blob Storage, GCS) and that your CI/CD environment can access it.
  • Permissions: The CI/CD runner must have appropriate permissions to interact with your cloud provider.
  • Environment Variables: Use environment variables for sensitive information like API keys or cloud credentials.
  • code
    terraform plan
    :     It's often a good practice to run
    code
    terraform plan
    first, especially for production deployments, and require manual approval before proceeding with
    code
    terraform apply
    .
  • Rollback Strategy: Have a clear plan for how to roll back infrastructure changes if a deployment fails.

Think of branches as development tracks and tags as milestones. You want to apply changes to the development track automatically, but only deploy to the production milestone after careful consideration and explicit tagging.

Example Workflow: GitHub Actions

Here's a simplified example of a GitHub Actions workflow that applies Terraform to staging on pushes to the

code
develop
branch and to production on pushes of tags starting with
code
v
.

Loading diagram...

This structured approach ensures that your infrastructure evolves predictably with your codebase, making deployments more reliable and manageable.

Learning Resources

GitHub Actions Workflow Syntax for GitHub Actions(documentation)

Official documentation detailing the syntax for creating GitHub Actions workflows, including how to trigger them based on branch and tag events.

GitLab CI/CD Pipeline Configuration(documentation)

Comprehensive guide to GitLab CI/CD YAML syntax, explaining how to define jobs, stages, and triggers for various Git events.

Terraform CI/CD Best Practices(tutorial)

A tutorial from HashiCorp covering CI/CD integration for Terraform, including strategies for automation and state management.

Automating Terraform Deployments with GitHub Actions(documentation)

Information on the official Terraform GitHub Action, which simplifies setting up Terraform in your CI/CD workflows.

Terraform Cloud CI/CD Integration(documentation)

Learn how Terraform Cloud can be integrated with CI/CD systems to manage Terraform runs, including triggers based on VCS events.

Jenkins Pipeline Syntax(documentation)

Official Jenkins documentation on Pipeline as Code, essential for configuring branch/tag-specific triggers in Jenkins.

Managing Terraform State(documentation)

Key concepts and best practices for managing Terraform state remotely, a critical component for CI/CD automation.

Understanding Git Tags(documentation)

A fundamental explanation of Git tagging, crucial for understanding how to version and trigger deployments.

CI/CD for Infrastructure as Code(video)

A video explaining the principles and benefits of CI/CD for IaC, often touching upon automated deployments.

Terraform `apply` command(documentation)

The official documentation for the `terraform apply` command, detailing its options and usage, which is central to automated deployments.