engineering-handbook/aws-infrastructure.md
Adam Moussa 4b5d39fb91
Add CDK version policy, update Node 24 and GitHub Actions CI/CD (#6)
* Update CDK version policy, Node 24 runtime, and GitHub Actions CI/CD

- Pin blessed aws-cdk-lib version (2.253.1) with upgrade procedure
- Update Lambda runtime default from Node 22 to Node 24
- Rewrite CI/CD page to reflect GitHub Actions reusable workflows
  (was still referencing CodePipeline/CodeBuild)

* Add pre-push hook for npm ci validation

Catches lock file drift locally before it breaks CI. Includes
install instructions in git-workflow.md.

* Add repo provisioning script

Automates the new-repo checklist: GitHub repo creation, OIDC deploy
role, repo secret, security features, CI/CD workflow stubs, and
pre-push hook installation. Supports both SAM and CDK stack types.

* Add shared VpnEc2Instance CDK construct

Reference construct for the VPN-accessible EC2 pattern used by
file-share and forgejo. Includes VPC/subnet lookup, SG, IAM role,
encrypted EBS, and DLM snapshots. Copy into lib/constructs/.

* Add post-deploy health check template

Template script for project-specific health checks. Copy to
scripts/health-check.sh — CD workflows run it automatically.
2026-05-14 18:39:13 -04:00

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Markdown

# 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 24.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.
## CDK Version Policy
Pin `aws-cdk-lib` to a known-good version. The current blessed version is **2.253.1**.
Why: aws-cdk-lib bundles transitive dependencies (`inBundle: true`). Certain versions (e.g., 2.254.0) break `npm ci` with phantom missing-package errors. npm `overrides` cannot fix bundled deps. Always test `npm ci` locally before pushing a version bump.
When upgrading, verify on a branch first:
1. Update `package.json` to the new version
2. Run `rm -rf node_modules package-lock.json && npm install`
3. Run `npm ci` — if it fails, the version is not safe
4. Run `npx cdk synth` — if it fails, the version is not safe
## 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.