CodePipeline pipelines created by the codepipeline.Pipeline class will automatically generate an S3 bucket to store artifacts in and a KMS key (CMK) to encrypt the objects in that bucket, if the bucket isn't specified via the artifactBucket property.

It would be helpful if one could specify an alias to assign to the autogenerated CMK so that other account users have an indication that the CMK is used for the pipeline. This could also help dissuade administrators from accidentally marking the CMK for expiration, which would render the pipeline unusable.