support systemd: `dynamicUser=yes`

[dvdsk]

Systemd supports dynamic users:

UNIX user and group pair is allocated dynamically when the unit is started, and released as soon as it is stopped. The user and group will not be added to /etc/passwd or /etc/group, but are managed transiently during runtime.

I do not know how uzers is implemented however from the test suite it seems to read /etc/passwd. When I query for the primary group from a program started by systemd as a service with dynamic user turned on I get None.

I think it would be nice to support this but it is an edge case. I would fix it myself if I had the time.

I feel its reasonable to close this with "wontfix".

[gierens]

It uses libc::getpwent to iterate over users. Afaik this goes beyond /etc/passwd alone, since it can retrieve SSSD users (at least with GLIC and not MUSL: #20). Are you using MUSL or GLIC? ... In any case, I added a help wanted tag as I probably won't find the time right now.

[dvdsk]

Are you using MUSL or GLIC?

I was using MUSL.

In any case, I added a help wanted tag as I probably won't find the time right now.

👍

[gierens]

I was using MUSL.

Ah, then this could actually be a MUSL issue, that it just doesn't support systemd dynamic users. It's the same for the SSSD issue I linked. Can you maybe try with a GLIBC build just to be sure? If that is actually the case, then my recommendation would be the same as in the other issue. If anyone has the time to actually reprogram these GLIBC features to work with MUSL then go ahead but it's an edge case and probably not that easy, otherwise the MUSL developers would have already included it there. But as I said, I added the help wanted tag for that.