Issues using "fakeroot" in Singularity

I am trying to build a singularity image within which I can act as root using the “–fakeroot” flag. However I get this error:

gercek@cpu288:~$ singularity build --fakeroot iblcore.sif docker://bdgercek/iblcore
FATAL:   could not use fakeroot: no mapping entry found in /etc/subgid for gercek

This was not an issue a few months ago when I’d been able to use fakeroot successfully. Did something change about the way Singularity is administered?


Update: This issue only occurred when I was trying to build on a compute node. When running the same command on the login node (:scream:) it runs fine.

Additionally, even when I build the container on the login node and attempt to run on compute nodes the fakeroot option fails.

Hi @Berk.Gercek

You are right to be horrified, as you know and everyone should know, computing on the login node is forbidden.

The problem should be solved /etc/subgid was not synchronized on compute nodes, could you try again, and give me a feedback about it?

Yes the command now works just fine (for both singularity build and singularity run) on compute nodes as well. Thanks!

So another issue that is related to this, is that when I do run a container with the “fakeroot” option, it takes roughly 10-20x longer to boot into the container than using a vanilla singularity command. The only hint I have as to why this occurs might be this warning:

WARNING: underlay of /etc/localtime required more than 50 (84) bind mounts

which appears each time. Any suggestions here?