Remote sites that support Singularity will default to running jobs in FermiGrid-like containers starting Wednesday, Oct. 16

WHAT ARE WE DOING?
Computing will be enabling the ability to select Singularity images for grid jobs on all sites that support Singularity, including FermiGrid. This change will make it easier for all users to run additional workflows offsite.

Singularity is an open-source computer program that performs operating-system-level virtualization known as containerization. Singularity containers enable users to run applications in a Linux environment of their choosing.

WHEN WILL THIS OCCUR?
Wednesday, Oct. 16, 2019; at noon Central Time

WHAT IS THE IMPACT TO YOU?
• After this change, jobs running on sites that support Singularity will run inside a Singularity container that is identical to a FermiGrid worker node by default. Users can override the container choice with appropriate jobsub options (see below).
• Jobs that run on FermiGrid will not be affected, unless a specific Singularity image is chosen by the user via the mechanism below.
• Note that this does NOT guarantee that your job will run in a Singularity container on all sites by default (only those sites that support Singularity).
• This change will not affect CMS jobs; it will only affect jobs submitted with jobsub.

WHAT DO YOU NEED TO DO?
If you wish to use a different Singularity image, you can override the default image with the following additional jobsub option (be careful to observe all quotes and backslashes):

–lines=’+SingularityImage=\”/full/path/to/image\”‘

Note that the path to the image must be visible on the work nodes. We thus strongly encourage you to use images in the /cvmfs/singularity.opensciencegrid.org repository.

Also, note that this does not guarantee that your job will run in a Singularity container. If you want to ensure that your job does so, add the following to your jobsub submission options:

–append_condor_requirements='(TARGET.HAS_SINGULARITY==true)’

That will prevent it from starting in a slot that does not support Singularity.

Please send an email to the Containers mailing list at containers@fnal.gov if you have any questions.