30days of Terraform

Creating Production-Grade Infrastructure with Terraform

Dwayne Chima's photo
Dwayne Chima
·

3 min read

Building infrastructure for production environments is more than simply writing Terraform configurations. It entails writing modular, reusable, and testable code that follows best practices. Today, we'll look at how to create production-ready Terraform configurations by concentrating on composability, testing, and validation.

Reusable and Composable Modules

Configurations should be modular to ensure that Terraform code is suitable for production. Instead of duplicating code, you may design reusable modules that contain both logic and resources. These modules may be used to create complex infrastructures while keeping settings tidy and manageable.

For example:

  • A VPC module for networking.

  • A Compute module for EC2 instances or GKE clusters.

  • A Storage module for S3 or GCP Buckets.

By using modules, teams can standardize components and reduce errors during deployments.

Testing Your Terraform Code

Testing infrastructure is critical for production. Terraform supports testing through tools like terraform validate, terraform plan, and frameworks like Terratest.

  1. Validation: Run terraform validate to check your configuration syntax.

  2. Dry-Run (Plan): Use terraform plan to preview changes.

  3. Unit Testing: With Terratest, write automated tests to validate resource behavior.

Testing ensures that changes won’t break your environment and can be integrated into CI/CD pipelines.

Validation with Pre- and Post-Conditions

Terraform configurations include pre and post conditions for resources, which allow validation during runtime.

  • Pre-conditions validate inputs before resource creation.

  • Post-conditions ensure outputs meet expected criteria after creation.

example:

resource "aws_instance" "web" {
  ami           = "ami-123456"
  instance_type = "t2.micro"

  lifecycle {
    precondition {
      condition     = var.instance_count > 0
      error_message = "Instance count must be greater than zero."
    }
  }
}

Terraform also allows combining multiple conditions using logical operators (and, or, and not) in pre-conditions and post-conditions. This makes it possible to enforce more intricate rules during resource creation or validation.

data "aws_ec2_instance_type" "instance" {
  instance_type = var.instance_type
}

resource "aws_instance" "web_server" {
  instance_type          = var.instance_type
  ami                    = data.aws_ami.ubuntu.id

    lifecycle {
    precondition {
      condition = (
        data.aws_ec2_instance_type.instance.free_tier_eligible || 
        var.instance_type == "t2.small" 
      ) && (
        contains(["unsupported"], data.aws_ec2_instance_type.instance.ebs_optimized_support)
        )

      error_message = "Instance must be part of Free tier, or 't2.small', and must not be EBS optimized."
    }
  }
}

Versioning and CI/CD Integration

Production-grade infrastructure must integrate seamlessly into CI/CD pipelines. Here’s how:

  1. Module Versioning: Tag and version your Terraform modules in Git repositories. Use version constraints to manage dependencies.

  2. Pipeline Steps: Automate terraform fmt, validate, plan, and apply steps in CI/CD pipelines.

  3. State Management: Use Terraform backends (like S3 with DynamoDB) to secure and manage state files.

This approach ensures changes are reviewed, tested, and deployed consistently.

Conclusion

Refactoring your Terraform project for production means:

  • Breaking configurations into small, reusable modules.

  • Adding testing and validation.

  • Using pre/post conditions to enforce requirements.

  • Integrating with CI/CD pipelines for automation.

With these principles, your Terraform code becomes robust, scalable, and production-ready.

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