Transition from sys-cluster/singularity to app-containers/apptainer
In autumn 2021 the Singularity project joined the Linux Foundation and changed its name to Apptainer . The change has been reflected in the renaming of files and environment variables, as well as a reset of version numbers back to 1.0.0.
Apptainer packages include compatibility symlinks to old Singularity executables, provide bash-completion rules for both the old and the new name, continue to honour old environment variables, and will upon the first run import user data from Singularity directories. Therefore, for most users it will be sufficient to deselect the old package and install the new one, e.g.:
emerge --deselect sys-cluster/singularity emerge app-containers/apptainer
However, customisations made to system-wide configuration in /etc/singularity will have to be applied to /etc/apptainer by hand.