Top 5 Terraform Module Versioning Best Practices

Estimated reading time: 9 minutes

Last updated on October 25th, 2024 at 02:58 pm

Introduction

Importance of Versioning in Terraform Modules

Terraform modules versioning is critical for your infrastructure as a code (IaC) stability and predictability.

Following the “Terraform Module Versioning Best Practices” allows the team to make changes effectively without breaking changes in production, and enables to run the different versions of the same module without conflict.

Common Challenges in Terraform Module Versioning

Terraform module versioning targets some common challenges such as:

1. Managing backward compatibility
2. Document changes
3. Automated versioning process

Without Terraform module versioning best practices in place, the team can face issues with the module conflict and more importantly unexpected behaviour in infrastructure, downtime, and difficulties in tracking changes

Before diving into the “Terraform Module Versioning Best Practices” let’s understand what Terrafromm module versioning and best practices are.

Understanding Terraform Module Versioning

What is Terraform Module Versioning?

Terraform module versioning is the method of assigning unique version numbers to the various releases of a Terraform module.

You might think why do we need the unique version number?

Assigning the unique version number helps track code changes, compatibility, and dependencies on other modules.

Benefits of Proper Versioning

Let’s discuss the benefits of using the proper version of Terraform modules:

• Stability: Ensure the changes do not break anything in the existing infrastructure.
• Traceability: Easily track what code changes were made in each version.
• Collaboration: Encourage team collaboration with clear documentation on which module version to use.

Terraform Module Versioning Best Practices

1. Follow Semantic Versioning (SemVer)

Semantic Versioning (SemVer) is a de-facto standard that is a widely adopted version scheme used to convey meaning about code changes using the version numbers: Major, Minor, and Patch.

Major, Minor, and Patch Versions:

Module version number becomes:

version-number.Major.Minor.Patch

Examples:

• Initial release: v1.0.0
• Backward-compatible feature added: v1.1.0
• Bug fix: v1.1.1
• Patch release: v1.1.2
• Breaking change: v2.0.0

2. Maintain Backward Compatibility

Backward compatibility is a crucial aspect of the Terraform module versioning. Backward compatibility ensures the existing configuration and code will work with the new module version, even if you update to the latest version.

Keep maintaining backward compatibility safeguards for the existing module users promising the latest feature for new users.

Deprecating Warnings:

When you want to discontinue support for certain API or code parts, provide a clear warning in your module output along with the documentation.

output "deprecation_warning" {
  value = "The 'old_feature' will be removed in version 2.0.0. Please switch to 'new_feature'."
}

This makes sure whenever the user runs the Terraform code, this deprecating warning is displayed!

Handling Breaking Changes:

After deprecating the feature now it is time to handle the breaking changes.

Increment the major version of the Terraform module and write the detailed steps to migrate from the old feature to the new one.

Examples:

• From v1.2.5 to v2.0.0 due to breaking API change.

3. Document Version Changes

Document! Document! Document! – This single Terraform module versioning best practices is the most important. Don’t overlook it!

Write the proper documentation of the code changes, how to migrate from one version to another, and known issues to help users understand what changes and how they affect the infrastructure.

Changelog Management:

Opt-in for the changelog management. Maintain the CHANGELOG.md file at the root of your Terraform module and document all the changes.

# Changelog
### 1.1.4
### Released 5/21/2024

#### Features:
-Added support for XXX

#### Bugfixes:
- Fixed issue XXX
- Fixed the display issue XXX

#### Misc:
- Improved XXX

Communicate Updates to Users:

Communicate and notify the users about new releases and deprecated features with the release notes, changelog, and documentation updates.

4. Automate Versioning with CI/CD Pipelines

You can implement all the Terraform module versioning best practices with the automation. Automation will keep the configuration and change consistent in versioning and reduce human errors.

The best practice is integrating it with CI/CD tools like Jenkins, GitHub Actions, or Gitlab CI to automate the versioning.

name: AutoRelease
on:
  push:
    tags:
      - 'v*.*.*'
jobs:
  release:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      - name: Publish module
        run: terraform publish

The sample YML is for the GitHub Action to release and tag version with SemVer v*.*.* automatically.

5. Use Version Constraints in Terraform Configurations

Specify the version number in your Terraform main.tf to fix it and avoid breaking changes due to automatic module upgrades.

Specify the Version Ranges

Define version constraints in your Terraform configuration:

module "aws" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "~> 2.0"
}

Compatibility Check

Test your infrastructure in your local environment with the new module version before applying it in production.

Ensure the compatibility before updating the version constraints.

Terraform Module Versioning Best Practices: Tools & Resources

Terraform module versioning best practices require the right tools and resources, with that you can automate the entire process and consistency. Effectively managing the Terraform module version provides a better experience for the user and developer.

1. Version Control System (Git, GitHub, GitLab)

The version control system is important for managing code changes and versions.

You might be familiar with popular tools such as Git, GitHub, and GitLab, which provide out-of-the-box support for tracking the module version and collaborating with the team members.

Example Workflow for GitHub

# Tagging a new module version
git tag v1.0.0
git push origin v1.0.0

# Creating a release in GitHub
gh release create v1.0.0

2. Terraform Registry

The Terraform registry is a centralized place to store and publish all your Terraform modules. It’s a convenient way to publish and distribute modules with your team members.

Terraform modules published on the Registry make it easy to discover and handle versioning accurately. Registry follows the Terraform module versioning best practices and supports the semantic version making it easy to manage and update.

Publish Terraform Module:

1. Prepare your module: Follow the best practices and documentation.
2. Tag Version: Use Git tags and SemVer to create the version of your module.
3. Publish to Registry: Use Terraform CLI or CI/CD tools to publish your module to the registry.

# Tagging and pushing a new version
git tag v1.2.0
git push origin v1.2.0

# Publishing to Terraform Registry
terraform publish

3. CI/CD Tools (Jenkins, GitHub Actions, GitLab CI)

Integrate with your Continuous Integration and Continuous Deployment (CI/CD) tools to automate the testing, creating new versions and releasing them to the Terraform registry. Test every change and validate before deploying and releasing.

Terraform Module Versioning Best Practices: Common Issues

When you implement the Terraform module versioning best practices, it’s important to keep an eye on the command issues that can jeopardize the stability and predictability of your infrastructure.

Let’s check the most common mistakes and how to prevent them:

1. Ignoring Semantic Version

Semantic Versioning (SemVer) is a widely adopted standard for managing the version and dependencies. Ignoring the SemVer can lead to major issues and make it difficult to update the module.

SemVer Adoption

Define the standard and follow the semantic versioning in your projects. For example, v1.0.0 indicates the first stable release, v1.1.0 indicates features without breaking changes, and v1.1.1 indicates bug fixes.

Educate Team

Educate your development team about SemVer and define standards. Ensure all team members understand and follow the semantic versioning.

Enforce Rule with CI/CD

Use automated ways to enforce the semantic rule with CI/CD. You can create a CI/CD job that can check the version number and the incremented number according to changes.

2. Lack of Documentation

Without proper documentation, users might misunderstand the available attribute and the changes in new modules lead to configuration errors.

Maintain Changelog

Write and keep up to date for the CHANGELOG.md file with all changes, added features, bug fixes, and breaking changes.

Use Release Notes

When you publish the new version of the Terraform module, publish the release notes for each version with detailed changes, migration steps, and depreciation warnings.

3. Lack of Testing Before Release

Terraform module versioning best practices encourage testing the version before release. Releasing the new module without proper testing can lead to unexpected issues in the production environment and potential downtime for service.

Automated Testing

Utilize the automated tests for your module version testing. Use the built-in tools terraform validate, terraform plan, and terraform apply for testing.

Terraform Validate vs Plan: Understanding the Key Differences

Version Testing

Test each version before the release, especially with the existing configuration to ensure backward compatibility.

Terraform Module Versioning Best Practices: FAQs

By following these Terraform module versioning best practices, you can ensure that your Terraform modules are versioned properly, providing stability and predictability to your infrastructure process.