AWS CloudFormation
- What it is
- infrastructure as code for AWS. Describe resources in a YAML or JSON template; CloudFormation provisions them in the right order.
- Free — you pay only for the resources created.
- Core concepts
- Template — the declarative definition. Stack — the deployed instance of a template. Delete the stack, delete the resources.
- Change sets — preview exactly what will change before applying.
- Drift detection — find resources someone modified manually outside the template.
- StackSets — deploy one template across many accounts and Regions at once.
- Automatic rollback on failure keeps the stack consistent.
- Why it matters for the exam
- Repeatability, version control, disaster recovery (“recreate the whole environment in another Region”), and eliminating configuration drift.
- Not to be confused with
- AWS CDK — write infrastructure in TypeScript/Python; it compiles to CloudFormation.
- AWS Elastic Beanstalk — AWS chooses the architecture for you; CloudFormation is you specifying it exactly.
- Terraform — third-party, multi-cloud equivalent.