1. CloudFormation

Infrastructure as Code (IaC) service — like Ansible or Terraform but native to AWS.

Purpose

• Automates creation, configuration, and management of AWS infrastructure using code (YAML/JSON templates).

Key Concepts

• Template → Declarative file describing resources (EC2, S3, RDS, etc.)
• Stack → A deployed instance of a CloudFormation template.
• Change Set → Preview of what changes will happen before applying.
• Nested Stacks → Reusable modular stacks (for large infra).
• Parameters/Outputs → Variables in templates to make them reusable.

Nuances

• AWS-native, integrates seamlessly with IAM, EC2, ECS, etc.
• State is managed automatically (unlike Terraform which uses a local or remote state file).
• Slow to deploy large infra compared to Terraform but best for AWS-only environments.
• You can use CloudFormation + CDK (Cloud Development Kit) for more readable, code-based definitions (TypeScript/Python).

Best Practices

• Store templates in Git + automate via CI/CD.
• Use Change Sets before updating stacks.
• Split large stacks into nested stacks.