Make GaudiExec prepare virtual

[mesmith75]

We should have the option to run the GaudiExec build in a container if need be so we can submit very old slc5 stacks

[egede]

I seem to remember that there is some support available for this within the LHCb software stack already. Can we just hook into that?If it relies on singularity, we might unfortunately hit the intermittent problems about running singularity on lxplus. The long standing bug-report I have had about it was closed with wont fix, use podman instead a few weeks back.

[mesmith75]

Unfortunately the LHCb software stack is not quite there. You can use lb-run with a container quite nicely (lb-run --container=singularity DaVinci/v32r2p18) but unfortunately not lb-dev. There is lb-docker-run but that needs you to have docker running. The best solution I have is

singularity exec -e --bind /cvmfs docker://gitlab-registry.cern.ch/lhcb-core/lbdocker/slc5-build:latest bash -c ". $LBENV_ENTRYPOINT
> lb-dev DaVinci/v32r2p18
> cd DaVinciDev_v32r2p18
> make"

but its not super nice. I'll have a look at the LHCb scripts and see if it would be straightforward to implement a singularity type thing.

[mesmith75]

Superseded by #2320