Terraform

• Terraform: A tool for defining and provisioning infrastructure as code, enabling you to create, manage, and update resources in a declarative and repeatable way.
• Terragrunt: A wrapper for Terraform that simplifies managing complex infrastructure setups by promoting DRY principles, automating workflows, and handling environment-specific configurations and dependencies.

Terraform interacts directly with provider APIs to create and manage resources, offering flexibility, speed, and multi-cloud support, while CloudFormation relies on AWS's orchestration engine, which can suffer from limitations like slow updates, fewer customization options, and challenges handling complex dependencies.

Brief key differences with this approach:

• Cloudformation drift detection less comprehensive. Terraform actively detects and reconciles drift.
• Cloudformation fails stack updates and rollback. Terraform errors are granular showing exactly what failed and allows for partial retries
• Cloudformation can re-use resources but takes up front planning. Terraform allows for fine-grain control enabling updates without resource replacement.
• Cloudformation lacks state management. Terraform maintains a explicit state file offering a better control over changes.
• Both serve as infrastructure as code (IaC)

Rough layout based on some of our infrastructure

Generic layout, subject to change.

terraform/
├── modules/
│   ├── s3_cloudfront/           # Module for SPA hosting (S3, CloudFront, OAI)
│   ├── route53/                 # Module for DNS management
│   └── rds/                     # Module for RDS Serverless
├── environments/
│   ├── nonprod/
│   │   ├── dev/
│   │   │   ├── sp-web-app/      # SPA resources for nonprod/dev
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── route53/         # Route53 for nonprod/dev
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── services/        # Services for nonprod/dev
│   │   │   │   ├── nodejs/
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── java/
│   │   │   │       └── terragrunt.hcl
│   │   ├── stage/               # Same structure for stage
│   │   │   └── ...
│   │   ├── perf/                # Same structure for perf
│   │       └── ...
│   ├── prod/
│   │   ├── dryrun/              # Same structure for prod/dryrun
│   │   │   └── ...
│   │   ├── prod/                # Same structure for prod/prod
│   │       └── ...
├── terragrunt.hcl               # Global configuration for shared settings