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Minos-singularity

Motivation

Minos does not have the resources to build and test our software under SL7,
and support for RedHat 6 ends in November 2020.
We plan to continue running under SL6 by using the Singulrity SL6 container provided by Fermilab.

Singularity runs as a user-space non-privileged image, so should be useful on any future systems.

This is key to our short term analysis needs, as well as Data Preservation concerns.

Running

To run in a Singularity SL6 environment on Fermilab systems, run the script

/minos/app/script/sing

Then source your .profile or .bashrc file.

You should then be able to run standard loon jobs, and build and run test releases.

We do not yet have a Centos 8 host available for testing Singularity.

Grid

From Art Kreymer issue 24897(https://cdcvs.fnal.gov/redmine/issues/24897):

According to the document https://cdcvs.fnal.gov/redmine/projects/fife/wiki/Singularity_jobs

it seems we need to start submitting jobs with

-l '+SingularityImage=\"/cvmfs/singularity.opensciencegrid.org/fermilab/fnal-wn-sl6:latest\"'
--append_condor_requirements='(TARGET.HAS_SINGULARITY=?=true)'

instead of

--OS=SL6

Working with a Test Release

From Art Kreymer issue 24897(https://cdcvs.fnal.gov/redmine/issues/24897):

The Singularity image does not have a functional /etc/krb5.conf file,
so you cannot kinit or ssh from this environment.
Hence no access to CVS.

I have created a workaround :
We need to set an environment that uses a current krb5.conf,
and that does ssh with the appropriate default options.

export KRB5_CONFIG=/minos/app/scripts/krb5.conf
export CVS_RSH=/minos/app/scripts/cvsrsh

Support

See development discussions in https://cdcvs.fnal.gov/redmine/issues/24897

We were guided by a talk by Marco Mambelli
https://indico.fnal.gov/event/20902/contributions/59849/attachments/37476/45542/FIFE_Singularity-190530.pdf
the overall Singularity documentation at
https://sylabs.io/docs/

and work by Annie, see notes on

Building
https://cdcvs.fnal.gov/redmine/projects/annie_experiment/wiki/Building_Containers_at_Fermilab

Submitting
https://support.opensciencegrid.org/support/solutions/articles/12000024676-docker-and-singularity-containers#submitting-your-docker-container-to-
the-open-science-grid-repository

Using
https://cdcvs.fnal.gov/redmine/projects/annie_experiment/wiki/ANNIE-GPVM_Singularity_Containers

The /minos/app/scripts/sing script is quit primitive, and does not source your .bashrc or .profile

NOvA is also using Singularity, via a more powerful script
https://cdcvs.fnal.gov/redmine/projects/novaart/repository/entry/trunk/setup/sl6.sh