cdk-bucket-deployment-memory-unconfigured

What it flags

CDK code that uses BucketDeployment without setting the memoryLimit property, on projects where the memory default is still relevant.

• aws-cdk-lib 2.267.0 or later is not flagged: the default memory limit is 1024 MB there.
• Older pinned versions are flagged with an upgrade recommendation.
• When the aws-cdk-lib version cannot be resolved (for example a caret range without a lockfile), the rule falls back to recommending an explicit memoryLimit. The version is resolved from the committed lockfile when available, then from an exact pin in package.json.

Why it matters

BucketDeployment uses a Lambda-backed custom resource. Before aws-cdk-lib 2.267.0 the default was 128 MB, which can throttle S3 sync to tens of KB/s and cause slow deploys or 15-minute timeouts on non-trivial website assets. aws-cdk-lib 2.267.0 raises the default memory limit to 1024 MB.

Recommended approach

Prefer upgrading, or set memoryLimit explicitly:

new BucketDeployment(this, "Deployment", {
  sources: [Source.asset("./dist")],
  destinationBucket: bucket,
  memoryLimit: 1024,
});

Verification

Compare the deploy step duration before and after upgrading aws-cdk-lib or setting memoryLimit.

Caveats

• Larger values (e.g., 1024–3008 MB) reduce deploy duration but increase cost per invocation.
• The optimal value depends on asset size and deployment frequency.