Dynamic userns=keep-id:uid for container USER

[KenMacD]

When running rootless containers that have a USER line in their Containerfile I often have to add an argument like:

--userns=keep-id:uid=1000,gid=1000

This works fine provided the UID/GID in the container is 1000:1000, but will fail in cases where another id is used, or in cases where there's no USER line (or it's overridden by --user).

I'd like to know if there's a way to dynamically select the container user id for the keep-id option, and if not perhaps suggest it be added

[eriksjolund]

I wrote a Bash script to detect the need for --userns=keep-id:uid=1000,gid=1000.
The container is started and then the script checks the ownership of files created in anonymous volumes.
https://github.com/eriksjolund/podman-detect-option
Status: It's a bit half-baked. I think I have forgotten to add --user 0:0 in a few places.