(cli): Add cdk publish command for asset publishing

[hoegertn]

Describe the feature

Add a new cdk publish CLI command that uploads synthesized assets (container images, Lambda bundles, file assets, etc.) to their respective destinations without performing a deployment.

Use Case

In CI/CD pipelines, the recommended best practice is to separate the build/publish phase from the deployment phase:

Synthesize (cdk synth) - Generate CloudFormation templates and asset manifests
Publish - Upload all assets (Docker images, Lambda ZIPs, S3 files) to their destinations
Deploy - Deploy stacks sequentially across stages/environments (without re-uploading assets)

Currently, cdk deploy combines asset publishing and deployment into a single operation. This creates challenges in enterprise CI/CD pipelines:

• Immutable artifacts: Assets should be published once and reused across multiple deployments (dev → staging → production)
• Separation of concerns: Build/publish should complete before any deployment begins
• Reduced deployment time: When deploying to multiple stages, assets only need to be uploaded once
• Atomic releases: All assets are verified to be published before any deployment starts
• Pipeline structure: Most CI/CD systems (GitHub Actions, GitLab CI, CodePipeline, Jenkins) work best with distinct publish and deploy stages

The only way to achieve this workflow today is by installing and using the cdk-assets package directly:

This approach has drawbacks:

• Requires an additional dependency
• Not well documented in the main CDK documentation
• The API and usage is less discoverable than built-in CLI commands
• Users must understand the internal asset manifest structure

Proposed Solution

Add a cdk publish command to the CDK CLI.

Other Information

• This aligns with the CDK Pipelines concept where assets are published before deployment
• The underlying functionality already exists in cdk-assets - this would expose it as a first-class CLI command

If this is implemented, it would be also beneficial to have an option in the cdk deploy command to skip publishing during the deploy step.

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.x

Environment details (OS name and version, etc.)

all

[hoegertn]

@mrgrain as discussed at RIV