Why IaC Matters in Serverless Applications

Introduction

Serverless is a cloud architectural pattern in which server resources are automatically managed by the cloud provider, enabling developers to focus primarily on application logic rather than infrastructure management.

The Problem

The challenge with serverless architectures is that, if not implemented correctly, they can quickly become difficult to manage. Some common difficulties include:

• Difficulty separating stages (e.g., dev, staging, prod)
• Challenges in implementing automated tests
• Complexities in managing permissions
• Difficulty versioning configuration
• Manual operations via the cloud console are often slower and error-prone

The Solution

The solution is straightforward: Infrastructure as Code (IaC). The idea is to describe your infrastructure using declarative files, such as YAML or Terraform configuration files. By doing this, you can organize both infrastructure and application code, enabling automation, consistency across environments, and easier collaboration between teams.

How IaC Helps in Serverless

Using Infrastructure as Code in serverless architectures addresses the challenges mentioned earlier:

• Stage Management: Define separate configurations for dev, staging, and production, ensuring isolation and reducing human error.
• Automated Testing: Infrastructure can be provisioned in test environments automatically, enabling end-to-end testing before deployment.
• Permissions Management: IAM roles, Lambda policies, and API Gateway permissions are codified, avoiding manual misconfigurations.
• Configuration Versioning: Infrastructure definitions are stored in version control, providing history and traceability of changes.
• Faster Deployments: Manual operations are replaced with automated pipelines, reducing deployment time and minimizing errors.

By codifying both the application and the infrastructure, IaC transforms serverless development from a potentially chaotic process into a structured, scalable, and maintainable workflow.

Exemple: Terraform

Terraform allows you to define your serverless infrastructure as code in a modular and reusable way. Here’s a simplified example of how to deploy an AWS Lambda function with an API Gateway endpoint:

provider "aws" {
  region = "us-east-1"
}

module "get_user_lambda" {
  source           = "./modules/lambda"
  function_name    = "get-user"
  handler          = "src/handlers/get-user/handler.lambda_handler"
  runtime          = "python3.12"
  zip_path         = "${path.module}/../build/get_geofence_routine.zip"
  source_code_hash = filebase64sha256("${path.module}/../build/get_user.zip")
  environment_vars = { STAGE = var.stage }
}

module "geofence_api" {
  source                = "./modules/api_gateway"
  name                  = "api-${var.stage}"
  routes = {
    get_routine = {
      path              = "user"
      method            = "GET"
      lambda_invoke_arn = module.get_user.lambda_invoke_arn
    }
  }
}

Key Points:

• Modular Design: Each Lambda and API Gateway resource is defined as a reusable module.
• Environment Variables & Stages: Easily separate dev, staging, and prod environments using variables.
• Automated Deployment: Terraform ensures that changes are applied consistently and safely.

This approach allows teams to manage hundreds of Lambda functions in a structured and maintainable way, avoiding manual configuration in the AWS console.

Conclusion

Serverless architectures offer incredible scalability and simplicity, but managing them manually can quickly become complex and error-prone. Infrastructure as Code (IaC) solves this problem by enabling automation, consistency, and version control for both infrastructure and application code.

Using tools like Terraform, teams can define, deploy, and maintain hundreds of serverless functions in a structured and reusable way. IaC not only reduces human error but also accelerates development, testing, and deployment workflows, making serverless applications more reliable and easier to scale.

By adopting IaC, developers can focus on building features and improving user experience, while ensuring that the underlying infrastructure remains stable, consistent, and fully versioned.