# AWS Infrastructure

## IaC Strategy

- **SAM** is the default for new serverless stacks (Lambda + API Gateway + DynamoDB)
- **CDK** only for complex infrastructure (ECS, VPCs, multi-service compositions)
- Every deployed resource should be managed by CloudFormation
- No manually-created Lambdas, roles, or other resources outside of IaC

## Lambda Defaults

These apply to every Lambda in every project. Verify, don't assume.

| Setting | Value |
|---|---|
| Runtime | Python 3.12 or Node 22.x |
| Architecture | arm64 |
| Log retention | 60 days (explicit in IaC template) |
| Naming | kebab-case, matching the stack name prefix |

Never rely on the CloudWatch default for log retention. Always set `RetentionInDays` explicitly in the template.

## CloudFormation Outputs

Every stack should export:

- Function ARNs
- Any externally-consumable URLs (API Gateway endpoints, etc.)

## S3

- Every non-CloudFormation bucket must have `Purpose` and `ManagedBy` tags
- Define lifecycle policies in the IaC template
- Use Glacier Deep Archive for archival data

## README

Every repo must have a README that accurately describes:

- Project architecture
- Lambdas and services
- Data flow
- Configuration requirements

Update the README in the same commit where functionality changes. If a README is missing or outdated when you start working on a project, fix it as part of the current work.