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May 8 – 12, 2023
Norfolk Waterside Marriott
US/Eastern timezone

Apptainer Without Setuid

May 9, 2023, 5:45 PM
Marriott Ballroom IV (Norfolk Waterside Marriott)

Marriott Ballroom IV

Norfolk Waterside Marriott

235 East Main Street Norfolk, VA 23510
Oral Track 7 - Facilities and Virtualization Track 7 - Facilities and Virtualization


Dykstra, Dave


Apptainer (formerly known as Singularity) since its beginning implemented many of its container features with the assistance of a setuid-root program. It still supports that mode, but as of version 1.1.0 it no longer uses setuid by default. This is feasible because it now can mount squash filesystems, mount ext2/3/4 filesystems, and use overlayfs using unprivileged user namespaces and FUSE. It also now enables unprivileged users to build containers, even without requiring system administrators to configure /etc/subuid and /etc/subgid unlike other “rootless” container systems. As a result, all the unprivileged functions can be used nested inside of another container, even if the container runtime prevents any elevated privileges.

Consider for long presentation No

Primary author

Presentation materials

Peer reviewing