AWS CDK
Overview
Domain expertise for CDK construct authoring, deployment workflows, compliance, drift, importing resources, safe refactoring, and troubleshooting CDK CLI / CloudFormation errors.
When NOT to use: Raw CloudFormation YAML/JSON. SAM. Terraform/Pulumi. CI/CD beyond CDK Pipelines. Use builtin knowledge or specialized skills for these.
Critical Warnings
Deadly embrace: Removing a cross-stack reference deadlocks deployment (Export ... cannot be deleted as it is in use by ...). Preferred fix: weaken the reference first — CrossStackReferences.of($RESOURCE).produce(ReferenceStrength.BOTH) then WEAK, then remove (three deploys). Legacy fallback: two-deploy this.exportValue() recipe. See troubleshooting-deployment.
Construct ID changes cause replacement: Renaming/moving a construct changes its logical ID → CloudFormation replaces the resource (data loss for stateful resources). Always cdk diff before deploy. See refactor-and-prevent-replacement.
UPDATE_ROLLBACK_FAILED: Stack is stuck. Fix with cdk rollback $STACK or cdk rollback $STACK --orphan <LogicalId>. Express mode stacks are the exception — they cannot be rolled back at all. See troubleshooting-deployment.
Hotswap and express mode are development-only: --hotswap / --hotswap-fallback bypass CloudFormation and create drift on purpose; --express reports success before resources stabilize and disables automatic rollback. You MUST NOT use either in production. A failed --express deployment cannot be rolled back — recover by rolling forward with another --express deploy. See fast-deployments.
Non-empty S3 buckets persist after destroy: You MUST set both removalPolicy: DESTROY and autoDeleteObjects: true. Versioned buckets are worse — delete markers persist even after apparent deletion.
Common Workflows
| Task | Quick Command | Details |
|---|---|---|
| Bootstrap | cdk bootstrap aws://$ACCOUNT/$REGION | bootstrap-and-project-setup |
| New TS project | cdk init app --language typescript — use tsx, eslint-plugin-awscdk | bootstrap-and-project-setup |
| New Python project | cdk init app --language python — pin deps, use virtualenv | bootstrap-and-project-setup |
| Deploy | cdk synth --strict → cdk diff → cdk deploy | Always diff before deploy to production |
| Fast dev iteration | cdk deploy --hotswap-fallback, cdk watch, or cdk deploy --express — dev only, never production | fast-deployments |
| cdk-nag | Aspects.of(app).add(new AwsSolutionsChecks()) | compliance-and-drift |
| Drift | cdk drift $STACK (use --fail in CI) | compliance-and-drift |
| Import resource | cdk import (interactive or --resource-mapping for CI), cdk deploy --import-existing-resources | import-and-migrate |
| Refactor safely | cdk refactor --unstable=refactor — no property changes in same deploy | refactor-and-prevent-replacement |
Fast Deployments — Hotswap vs Express (dev only)
Both trade safety for speed and you MUST NOT use either in production.
Choosing between them: Use --hotswap / --hotswap-fallback for the fastest loop when you work mostly with hotswappable resources and drift does not matter. Use --express when drift is unacceptable, or your resources are not hotswappable.
Recovery workflows (hotswap drift via --revert-drift, rolling a failed --express deploy forward), the hotswappable-resource rules, and IAM/monitoring enforcement of the prod prohibition are all in the full guide: fast-deployments.
Troubleshooting
| Error | Cause → Fix |
|---|---|
| DeployFailed / DeploymentError | CDK error isn't the root cause. cdk deploy $STACK --verbose, then cdk --unstable=diagnose diagnose $STACK (CLI ≥ 2.1120.0); else aws cloudformation describe-events --stack-name $STACK --filters FailedEvents=true — the first _FAILED event is the cause. Details |
| NoCredentials / ExpiredToken / AssumeRoleFailed | aws sts get-caller-identity + cdk doctor. Expired SSO, missing env, missing sts:AssumeRole. Details |
| Asset errors (CannotFindAsset, FailedToBundleAsset, AssetBuildFailed, AssetPublishFailed) | Path wrong, Docker not running, or bootstrap bucket perms. Use path.join(__dirname, ...). Details |
| AppRequired | Add "app": "npx tsx bin/my-app.ts" to cdk.json. Details |
| AnnotationErrors | Fix the underlying issue; suppress with NagSuppressions only as last resort. Details |
| ConcurrentReadLock / ConcurrentWriteLock | rm -rf cdk.out then re-run. Parallel CI: --output ./cdk.out.$BUILD_ID. Details |
| BootstrapVersionValidation | Re-bootstrap. Match --qualifier everywhere. Details |
| DependencyCycle | Extract shared resource into third stack or use SSM for late-binding. Details |
| UnresolvedAccount | Set explicit env: { account, region } on stack. Commit cdk.context.json. Details |
| NoStacksMatched | CDK uses logical ID (2nd constructor arg), not CFN name. cdk list to find IDs. Details |
| Cannot find module (synth time) | Run npx tsc --noEmit, check cdk.json app path matches tsconfig.json outDir, delete stale .js files. Python: activate venv. Details |
| V1 import paths / duplicate aws-cdk-lib | V1 @aws-cdk/* imports, wrong Construct import, duplicate lib copies in monorepos. Details |
| Lambda Cannot find module (runtime) | Wrong handler value, missing AWS SDK v3 migration, Python deps not bundled. Details |
| API Gateway multi-stage conflicts | Set deploy: false on RestApi, create Deployment and Stage explicitly. Details |
Change didn't deploy under --hotswap | Changes to non-hotswappable resources are silently ignored and only logged — the command still reports success. Read the output; use --hotswap-fallback to force a CloudFormation deployment instead. Details |
Failed --express deploy / can't roll back | Express mode cannot use the Rollback Stack API, and a standard deploy MUST NOT be used to recover it. Roll forward: fix the cause, then cdk deploy $STACK --express. Details |
| Unexpected drift on a dev stack | Hotswap and cdk watch create drift by design. Until reverted, the live resources — not CloudFormation's records — are authoritative. Reconcile with cdk deploy $STACK --revert-drift, which uses Drift Aware Changesets to bring live resources in line with the template (updates reality to match desired state; does NOT rewrite CF records to match drifted resources). Details |
Construct Patterns
Prefer L2. Use L1 with Mixins/Facades when L2 lacks a property. Escape hatches: node.defaultChild → addPropertyOverride. See construct-patterns.
Additional Resources
- Search AWS documentation for "CDK Developer Guide", "CDK API Reference" and "CDK Pipelines" respectively
Security Considerations
- OIDC for CI/CD credentials (no static keys)
--custom-permissions-boundaryon bootstrapgrant*()for inter-resource IAMcdk-nag+--strictin CI- Stateful resources in own stack with
terminationProtection: true - Commit
cdk.context.json
