Using Terraform with Git branches to manage environments

In the world of Infrastructure as Code (IaC), the combination of Terraform and Git stands out for its elegance and efficiency. This tutorial aims to delve into how you can leverage Terraform alongside Git branches to manage different environments seamlessly. Whether you’re a beginner looking to understand the basics or an experienced developer seeking to refine your workflow, this guide is structured to offer valuable insights through practical examples.

Understanding the Basics

Before diving into the more complex aspects, it’s crucial to understand the fundamental principles behind using Terraform with Git branches. Terraform, an open-source infrastructure as code software tool created by HashiCorp, enables users to define and provision data center infrastructure using a high-level configuration language known as HCL (HashiCorp Configuration Language). Git, on the other hand, is a distributed version control system that helps developers manage and track changes in their code across different branches and versions.

By integrating these two powerful tools, developers can effectively manage separate environments (development, staging, and production) for their infrastructure projects. This setup not only ensures consistency across environments but also enhances collaboration among team members.

Setting Up Your Repository

To begin, you’ll need to set up a Git repository for your Terraform project. Let’s start with a basic structure:

mkdir terraform-environments 
cd terraform-environments 
git init 
mkdir environments 
cd environments 
mkdir development staging production 
echo "variable 'environment' {}" > variables.tf 
echo 'provider "aws" { region = "us-east-1" }' > provider.tf

This structure introduces separate directories for each environment within an overarching ‘environments’ folder. We’ve also added a basic variables and provider configuration file that applies to all environments.

Branching Strategy

With the repository set up, the next step is to establish a branching strategy that correlates with your environments. A common approach involves creating a branch for each environment.

git branch development 
git branch staging 
git branch production

This strategy implies that changes meant for a specific environment will be made in its corresponding branch. When you’re satisfied with the development and testing in the ‘development’ branch, you can merge those changes into the ‘staging’ branch for further testing and finally into ‘production’ for deployment.

Managing Terraform State

An important aspect of using Terraform with Git branches is managing the Terraform state file. To avoid conflicts and ensure a correct representation of each environment, it’s best to use remote state. Terraform supports various backends for remote state management, such as AWS S3, Google Cloud Storage, or Terraform Cloud.

For example, to configure the AWS S3 backend for your state files, you can add the following to each environment’s main.tf file:

terraform { 
  backend "s3" { 
    bucket = "my-terraform-state-bucket" 
    key    = "environments/<ENV_NAME>/terraform.tfstate" 
    region = "us-east-1" 
  } 
}

Replace <ENV_NAME> with the actual environment name (‘development’, ‘staging’, ‘production’). This setup ensures that each environment’s state file is stored separately and securely.

Workflow Example

Let’s walk through a simple scenario to illustrate how you might manage a change across your environments:

1. Create a new feature branch from the ‘development’ branch and make your Terraform changes.
2. Commit and push the changes to the remote repository.
3. Create a pull request to the ‘development’ branch and merge after review.
4. Once validated in the development environment, create a pull request to merge those changes into the ‘staging’ branch.
5. After staging testing, finally merge into ‘production’.

This workflow keeps your environments in sync and allows for incremental testing at each stage.

Advanced Techniques

As you grow more comfortable with the basics, you can explore advanced techniques like using Terraform workspaces or dynamic environment configuration to further improve your workflow.

Workspaces allow you to manage state files for different environments within the same directory structure, making it simpler to manage multiple environments without requiring a separate backend configuration for each.

Dynamic configurations use variables and Terraform’s conditional expressions to customize resources based on the environment. This can significantly reduce code duplication and streamline the management of your infrastructure code.

Conclusion

Integrating Terraform with Git branches presents a powerful strategy for managing infrastructure across multiple environments. By adhering to a structured branching strategy, utilizing environment-specific configurations, and leveraging Terraform’s capabilities for managing state and deployments, teams can achieve consistent, reproducible, and manageable infrastructure code. Embracing these practices enables smoother development flows and fosters collaboration within teams, ultimately leading to more resilient and scalable infrastructures.