Terraform State File Handling – 😇 or 😈?

/ Azure, Best Practices, Epic, Infrastructure as Code (IaC), Terraform / By
Single “monster”👹
vs.
multiple files?

# Status Quo 💭

HashiCorp Terraform, the open-source “Infrastructure as Code” (IaC) tool, has become a central part of many organizations’ cloud deployment strategies 📊. When it comes to managing cloud resources like on Microsoft Azure, Terraform offers a robust solution for defining and provisioning infrastructure. One powerful feature of Terraform that is often underutilized 😯 is the ability to work with multiple state files within a single project.

This article explains why it is essential to work with multiple Terraform state files in your Azure projects and how it can benefit your infrastructure management.

# What is a Terraform State File? 📄

Before delving into the importance of multiple state files, let’s briefly understand what a Terraform state file is exactly. 📄 In Terraform, the state file is a crucial component that keeps track ✅ of the current state of your Azure infrastructure. It records which resources have been provisioned, their attributes, dependencies, and configurations. This state file is a crucial piece of the puzzle because it allows Terraform to understand what changes need to be made when you run “terraform apply” and ensures the infrastructure’s desired state matches the actual state.

# Challenges of a Single State File 📄

In many Terraform projects, especially small ones, a single state file can suffice. However, as the Azure infrastructure grows, a single state file can become a bottleneck and a source of potential issues. The following list shows some challenges and issues associated with using a single state file:

Increased Complexity

Managing a large and complex infrastructure with many resources in a single state file can become challenging. It can be hard to keep track of resource dependencies and changes, leading to a higher chance of errors. 🚫
⛔👎

Concurrency Issues

When multiple team members work on the same Terraform project concurrently, a single state file can lead to conflicts and synchronization issues. It may result in one person’s changes overwriting another’s. Moreover, the state file is locked during a terraform run. 🏃‍♂️ Executing parallel runs at the same time are not possible and will cause issues.
⛔👎

Resource Dependencies & Low Performance

In a single state file, Terraform must maintain all resource dependencies, which can lead to slower execution times, especially when changes affect only a small portion of the Azure infrastructure. That means, one large state file is way slower, because it has to handle many cloud resources. 🐢
⛔👎

Risk of Corruption

A single state file is more susceptible to corruption, which can be catastrophic if it occurs, as it may lead to data loss or irreversible issues with your infrastructure. The “blast radius” is quite huge in case of file corruption. Therefore, version or backup state files periodically! Make sure that restore scenarios are working as well in a case of disaster!
⛔👎

# Benefits of Multiple State Files 📄📄📄

To address these challenges, Terraform allows to work with multiple state files within a single project. This approach offers several benefits:

Modularity & Better Performance

With multiple state files, you can break down your Azure infrastructure into smaller and manageable pieces. Each state file can represent a specific component or “layer” (e.g., network layer, connection layer, traffic/firewall layer, management layer, monitoring layer, etc.), making it easier to understand and maintain. Furthermore, the terraform runs are way faster, because the state file has to handle a small amount of resources.
✅👍

Improved Collaboration

Teams can work on different components with their own state files without interfering with one another. This reduces the risk of conflicts and simplifies collaboration.
✅👍

Reduced Complexity

Smaller state files are easier to manage. You can focus on a particular component without being overwhelmed by the entire infrastructure.
✅👍

Parallel Execution

Terraform can execute multiple state files in parallel, speeding up resource provisioning and updates. This is particularly beneficial for larger projects with extensive dependencies.
✅👍

Better Isolation

When errors occur, it is easier to pinpoint their source in smaller state files. This speeds up debugging and makes troubleshooting easier in case of an issue.
✅👍

# Best Practices for Using Multiple State Files

Here are some best practices for effectively utilizing multiple state files in your Azure projects:

Plan Your Project Structure

Carefully plan how to break down your Azure infrastructure resources into logical components or layers, each with its own state file. Consider using a modular approach (Link), where each module only manages a specific part of your infrastructure or application.
✔️

Naming Conventions

Use a consistent naming convention for your state files and resources to maintain clarity and organization.
✔️

Remote State Management

Consider using remote state management backends like Azure Blob Storage or Terraform Cloud for improved collaboration and version control. Work with Terraform workspaces (Link) to support multiple configurations and environments.
✔️

Version Control

Store your state files in a version control system (VCS), in an Azure Storage Account (Versioning enabled) or in the Terraform Cloud, so you can track changes and collaborate efficiently. Version, encrypt, and securely share the state files with your team.
✔️

Infrastructure as Code (IaC)

Leverage infrastructure as code principles to define your entire infrastructure using Terraform configuration files, ensuring consistency across your project. Use the Terraform Remote State (Link) to get the outputs from other state files, that can be used during the current/next execution.
✔️

# Conclusion 🙌

Working with multiple Terraform state files in your Azure projects can significantly improve the manageability, scalability, and collaboration of your infrastructure or application resources. By breaking down your project into smaller, modular pieces, you can address the challenges of using a single state file and take full advantage of Terraform’s capabilities. When used effectively, multiple state files empower your team to deploy and manage complex Azure infrastructures with greater confidence and efficiency.

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