prefer-cdk-asset-build-concurrency

Flags CI cdk deploy commands that build multiple Docker image assets without --asset-build-concurrency.

Why it matters

• CDK builds Docker image assets serially (build concurrency 1), so a deploy with several images waits for each build in turn.
• The CDK feature request that motivated the flag showed five 10-second images taking over 50 seconds serially versus about 10 seconds in parallel.
• --asset-build-concurrency N parallelizes Docker asset builds.

What it flags

• A repository whose CDK source contains two or more Docker image assets (fromImageAsset(...) or new DockerImageAsset(...)) and whose workflows run cdk deploy without --asset-build-concurrency.

Suggested action

• Add --asset-build-concurrency (for example --asset-build-concurrency 4) to the CI cdk deploy command.

Verification

• Compare cdk deploy wall-clock time before and after enabling --asset-build-concurrency, and watch for container registry rate limits or runner resource contention.

Compatibility notes

• The flag only applies to Docker-based bundling, not to ILocalBundling assets, which are built synchronously during synthesis.
• It requires a recent aws-cdk CLI (introduced in the 2.1099.0-2.1117.0 range). The rule stays silent when no workflow runs cdk deploy, or when the CDK source has fewer than two Docker image assets.