LHC@home

It may be confusing but Apptainer is just a new name for the software package formerly known as Singularity.
See: https://github.com/apptainer/apptainer

At least on Opensuse Tumbleweed the Apptainer package distributed with the TW repository runs (nearly) out of the box with ATLAS native.
The only ToDo is to add the BOINC user account running ATLAS tasks to the new apptainer group and restart the BOINC service:

[sudo] usermod -a -G apptainer boinc

Apptainer is also available in the ATLAS CVMFS area at

/cvmfs/atlas.cern.ch/repo/containers/sw/apptainer/x86_64-el7/current/bin/apptainer

At the moment the functionality is identical to Singularity but it may diverge at some point. In the future ATLAS tasks will all have to switch to Apptainer instead of Singularity, so I will update the ATLAS scripts to be able to use both, then at a later date Singluarity will be phased out.

David,
we have this discussion https://lhcathome.cern.ch/lhcathome/forum_thread.php?id=5813
about CentOS9 and CVMFS, do you know something about this new CentOS inside Cern-IT?

We are now testing using apptainer instead of singularity on the dev project

The idea is to use apptainer if it exists and works, and if it doesn't work fallback to singularity if it is installed locally. This means tasks should still work for people using a local singularity. If you would like to help out with testing please send me a private message for an invitation code to the dev project.

https://lhcathome.cern.ch/lhcathome/show_host_detail.php?hostid=10677417
[2022-09-11 04:56:22] apptainer is not installed, using version from CVMFS
[2022-09-11 04:56:22] Checking apptainer works with /cvmfs/atlas.cern.ch/repo/containers/sw/apptainer/x86_64-el7/current/bin/apptainer exec -B /cvmfs /cvmfs/atlas.cern.ch/repo/containers/fs/singularity/x86_64-centos7 hostname
[2022-09-11 04:56:23] apptainer isnt working: ERROR : Failed to create user namespace: user namespace disabled
[2022-09-11 04:56:23] 
[2022-09-11 04:56:23] It looks like user namespaces are not enabled, which are required when running apptainer from CVMFS.
[2022-09-11 04:56:23] Please run the following command as root to enable them:
[2022-09-11 04:56:23] echo "user.max_user_namespaces = 15000" > /etc/sysctl.d/90-max_user_namespaces.conf; sysctl -p /etc/sysctl.d/90-max_user_namespaces.conf
05:06:23 (6066): run_atlas exited; CPU time 0.254583