[ic4l]

We tried this initially

  FROM mirror.gcr.io/{image_name}

We received

  failed to resolve source metadata for mirror.gcr.io/

So it looks like these services may not be true mirrors, and just functioning as a library proxy with a cache.

If you're image is not cached on one of these then you may be SOL.

[da768]

During the last Docker Hub outage we found Google mirrors lost all image tags after a while. Image digest references would probably work