[HTCondor-users] Docker invalid image name

[Roberto Calandra <pkrmc@xxxxxxxx>]

Hello,
I just started using HTCondor because I would like to set up an infrastructure for performing scientific experiments using HTCondor + Docker (and in the future + GPUs).
In this moment I am kind of stuck because after installing and configuring HTCondor and Docker, in the moment when I try to submit a test job to condor, such as the following:

universe                = docker
docker_image            = ubuntu
executable              = /bin/cat
arguments               = /etc/hosts
should_transfer_files   = IF_NEEDED
when_to_transfer_output = ON_EXIT
output                  = out.$(Process)
error                   = err.$(Process)
log                     = log.$(Process)
request_memory          = 100M
queue 1

I get an error saying "Cannot start container: invalid image name: ubuntu".
I could find a similar errors mentioned in the tutorial here: https://research.cs.wisc.edu/htcondor/HTCondorWeek2015/presentations/ThainG_Docker.pdf
And I think that the problem is that the image is not automatically downloaded from docker-hub.
Now, is it normal that the image is not automatically downloaded? Is there some configuration file I need to modify? Or do I necessarily have to manually place a copy of the docker image in the submitting machine?

Thank you for you help!
-Roberto