I think you're not the only one that mentioned this omission, I'll throw in since it seems to be pretty poorly highlighted and has some surprising failure modes

I think you're not the only one that mentioned this omission, I'll throw in since it seems to be pretty poorly highlighted and has some surprising failure modes: When you use the USER directive to set up a working user in Dockerfile, be explicit about UID and use the numeric UID. What works 99% of the time is to use alpha username in the "USER" directive. You can get some surprising artifacts if the container runtime hits this rare bug[1]. There are likely several other great ways this can go wrong, as well. Somewhere deep in the manual, it is suggested that you should only use a numeric UID, even though USER accepts an alphanumeric username most of the time, but if you look at container images built by OpenShift and other pro docker-ers, you will see they always do this with a numeric UID. [1]: https://forums.docker.com/t/unable-to-find-user-root-no-matching-entries-in-passwd-file/26545 https://forums.docker.com/t/unable-to-find-user-root-no-matc...