Design image type

[bobcatfish]

The work for this task is to design this feature and present one or more proposals (before implementing).

Expected Behavior

One of the features we want the Pipeline to have is to have strong typing around concepts that will be used commonly in k8s centric CI/CD pipelines.

One of the concepts we want to have strong typing around is a "container image", which is something that could be produced by a Task as an output, and published to an artifact store, and may be used by subsequent Tasks for testing or deploying.

Some attributes we'd probably like include:

• name
• tag
• digest (could be unknown until the image is built)

Actual Behavior

This concept only exists theoretically, but in this example pipeline we have a builtImage attribute on an artifact store binding, declaring what we'd like the built image to be called:

Additional Info

• Digests are more reliable than tags since they are immutable!
• See Design: Ensure same sources/inputs used throughout pipeline #11 re. ensuring we are using the same image throughout our pipeline.
• See discussion around build artifacts note doc visible to members of knative-dev@googlegroups.com

[bobcatfish]

Closing this issue as @pivotal-nader-ziada and @shashwathi added an initial version of the image type at https://github.com/knative/build-pipeline/blob/1c4deea8de70d40ded6cab8d64fe303d65ce2970/pkg/apis/pipeline/v1beta1/image_source.go in #39 !