Allow users to stop public Docker images from getting cached

This feature request is to add the ability for users to stop their public Docker images from being cached in the Pipeline or provide them an option to invalidate the specific Public images being cached.

The Pipeline cache the public images for better performance so that the next time when the same image is being used, it uses the image from the cache instead of pulling the image from the registry and saving the network bandwidth. However, when the users make their image from Public to Private in the registry, the Pipeline build doesn't pull the image from the registry (irrespective of authentication provided or not for the registry in the Pipeline configuration) instead they get the older image from the cache which is a bug in the system. This is an issue with the Pipeline and builds using the older image.

There are few workarounds available until the feature is implemented or the bug is fixed for the users to provide an option to stop their public images from being cached or provide an option to invalidate the specific images:

• Make the image Public again, pull the image from the Pipeline build, and make the image back to Private. This workaround has its own security problem
• Create a new tag of the image, push it into the registry and use this new tag in the Pipeline build. Since this is a new tag, Pipeline will not use the cached image from the registry instead it will use the image from the Private registry using the credentials provided.