Idea: Providing our stack within a docker/singularity container

[mboisson]

Idea suggested by @preney

[mboisson]

@rptaylor may have some insight on this.

[rptaylor]

There are various ways to mount CVMFS repos as an unprivileged user.
Could try e.g. https://github.com/cvmfs-contrib/cvmfsexec
So there should be some options for doing this in a container.
Some more info: https://indico.cern.ch/event/813800/contributions/3830191/attachments/2031830/3401805/PreGDBCvmfsexec20200504.pdf

[rptaylor]

That being said, to the maximum extent possible it is better to set up CVMFS on the host outside the container, and mount the repos into the container when you start it, so that the cache can be shared and persisted. Starting up an empty CVMFS cache inside your container for a private CVMFS client in the container is not very efficient.

Possibly an intermediate option would be to keep a persistent shared cache somewhere on the node, bind mount it into the container, and have the CVMFS client run in the container.

[rptaylor]

The new "pre-mount" feature may also help:
https://cvmfs.readthedocs.io/en/stable/cpt-releasenotes.html#pre-mounted-repository
https://cvmfs.readthedocs.io/en/stable/cpt-configure.html#sct-premount

Also described on slide 15 here:
https://indico.cern.ch/event/813800/contributions/3830185/attachments/2031899/3400849/cvmfs-pregdb2005.pdf

[mboisson]

@preney, do you think you will have some time to try this soon ?

[mboisson]

Some information that is relevant to this :
EESSI/filesystem-layer#10

[mboisson]

This has been done by EESSI :
https://eessi.github.io/docs/pilot/

@preney, can you look at reproducing this for our stack ?

[mboisson]

The docker file is here : EESSI/filesystem-layer#35