AWS CloudFormation

What is AWS CloudFormation?

AWS CloudFormation is AWS’s in-house service for Infrastructure as Code (IaC). Instead of manually creating servers, networks and databases via the AWS web interface, you describe the entire infrastructure in a template – a text file in YAML or JSON format. CloudFormation reads this template and automatically creates all the resources described within it.

This turns infrastructure into code: it can be versioned, checked during a code review and recreated identically as often as required. Manual clicking – the most common cause of hard-to-find configuration differences between environments – is eliminated.

How CloudFormation works

• Template: The template declaratively describes the desired target state of the infrastructure.
• Stack: A specific instance of a template – all resources created from it are managed as a single unit.
• Change Set: A preview that shows, before any change is made, exactly what would be created, modified or deleted.
• Drift Detection: Detects when resources have been subsequently modified manually and deviate from the described state.

Advantages of Infrastructure as Code

The declarative approach of CloudFormation offers several tangible benefits. Environments such as staging and production can be created from the same template and are therefore guaranteed to have an identical structure. Every change to the infrastructure is traceable in the version history. And should an entire environment be lost, it can be fully restored from the template in a short time. If a change fails, CloudFormation can automatically reset the stack to its previous state.

CloudFormation and Terraform

CloudFormation specialises in AWS and is deeply integrated with it. The equally widespread Terraform follows the same Infrastructure-as-Code approach, but works across providers. For pure AWS environments, CloudFormation is the obvious choice; in multi-cloud scenarios, Terraform comes into its own. Both tools solve the same fundamental problem.

CloudFormation in SMEs

As soon as an infrastructure outgrows a few resources, Infrastructure as Code is the right foundation. CloudFormation ensures that knowledge of the environment does not exist solely in the minds of individuals, and makes every change verifiable. It is therefore also a key component of automated CI/CD pipelines, in which infrastructure changes are rolled out in a controlled manner.