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3.17 Singularity Support

Note: This documentation is very basic and needs improvement!

Here’s an example configuration file:

  # Only set if singularity is not in $PATH.  
  #SINGULARITY = /opt/singularity/bin/singularity  
 
  # Forces _all_ jobs to run inside singularity.  
  SINGULARITY_JOB = true  
 
  # Forces all jobs to use the CernVM-based image.  
  SINGULARITY_IMAGE_EXPR = "/cvmfs/cernvm-prod.cern.ch/cvm3"  
 
  # Maps $_CONDOR_SCRATCH_DIR on the host to /srv inside the image.  
  SINGULARITY_TARGET_DIR = /srv  
 
  # Writable scratch directories inside the image.  Auto-deleted after the job exits.  
  MOUNT_UNDER_SCRATCH = /tmp, /var/tmp

This provides the user with no opportunity to select a specific image. Here are some changes to the above example to allow the user to specify an image path:

  SINGULARITY_JOB = !isUndefined(TARGET.SingularityImage)  
  SINGULARITY_IMAGE_EXPR = TARGET.SingularityImage

Then, users could add the following to their submit file (note the quoting):

  +SingularityImage = "/cvmfs/cernvm-prod.cern.ch/cvm3"

Finally, let’s pick an image based on the OS – not the filename:

  SINGULARITY_JOB = (TARGET.DESIRED_OS isnt MY.OpSysAndVer) && ((TARGET.DESIRED_OS is "CentOS6") || (TARGET.DESIRED_OS is "CentOS7"))  
  SINGULARITY_IMAGE_EXPR = (TARGET.DESIRED_OS is "CentOS6") ? "/cvmfs/cernvm-prod.cern.ch/cvm3" : "/cvmfs/cms.cern.ch/rootfs/x86_64/centos7/latest"

Then, the user adds to their submit file:

  +DESIRED_OS="CentOS6"

That would cause the job to run on the native host for CentOS6 hosts and inside a CentOS6 Singularity container on CentOS7 hosts.

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