Book Image

Mastering AWS CloudFormation - Second Edition

By : Karen Tovmasyan
Book Image

Mastering AWS CloudFormation - Second Edition

By: Karen Tovmasyan

Overview of this book

The advent of DevOps and the cloud revolution has compelled software engineers and operations teams to rethink how to manage complex infrastructures and build resilient solutions. With this AWS book, you’ll find out how you can use Infrastructure as Code (IaC) to simplify infrastructure operations and manage the modern cloud with AWS CloudFormation. This guide covers AWS CloudFormation comprehensively, from template structures to developing complex and reusable infrastructure stacks. It takes you through template validation, stack deployment, and handling deployment failures. It also demonstrates the use of AWS CodeBuild and CodePipeline for automating resource delivery and implementing continuous integration and continuous delivery (CI/CD) practices. As you advance, you’ll learn how to modularize and unify your template on the fly using macros or by fixating the version using modules. You’ll create resources outside of AWS with custom resources and catalog them with the CloudFormation registry. Finally, you’ll improve the way you manage the modern cloud environment on AWS by extending CloudFormation through the AWS serverless application model (SAM) and the AWS cloud development kit (CDK). By the end of this book, you’ll have mastered key AWS CloudFormation concepts and will be able to extend its capabilities for developing and deploying your own infrastructure.
Table of Contents (19 chapters)
Free Chapter
1
Part 1: CloudFormation Internals
4
Part 2: Provisioning and Deployment at Scale
9
Part 3: Extending CloudFormation

Validating the template

Whenever we execute aws cloudformation create-stack (or update-stack), CloudFormation will first validate the template, checking whether it is a valid JSON or YAML file (a syntax check) and whether there are any critical issues, such as circular dependencies.

Although template validation is a necessary step before stack deployment, many things will break stack deployment, even if validation succeeds:

  • Missing required resource properties
  • Syntax errors and typos in resource property names
  • Non-existent resource property values

We could continue with this list, but let’s move from theory to practice.

The command that runs template validation is straightforward:

$ aws cloudformation validate-template --template-body file://path_to_your_template

For example, if we want to validate our core template, we need to run the following command:

$ aws cloudformation validate-template --template-body file://core.yaml

If there is...