1. Finding a Theory of the Universe with
Docker and Volunteer Computers
Marius Millea
Lagrange Postdoctoral Fellow
Institut Lagrange de Paris

2. About Me
• I'm a cosmologist
• ...but I've always been really into
computers
• I work on analyzing data from a
satellite called Planck
• I'm the main developer at
Cosmology@Home

3. Thanks to...
Ben Wandelt Rom Walton Cam Boehmer
Original creator of
Cosmology@Home
A BOINC developer Introduced me to
Docker
...and many others

4. • Cosmology@Home is a volunteer-based computer cluster
Active computers:
(as of July 2015)

5. • Our aim is to better understand our universe
(in particular the mass of the neutrino particle)
Server
Volunteers
Possible universes

6. Outline
• Measuring the mass of the neutrino
particle with Planck
• Cosmology@Home and how Docker has
helped
• Future Docker use at Cosmology@Home
and in the field of physics in general

7. Why the science?
• Show you a definite
example of the type of
calculations we do
• Give you a sense of their
ever-changing nature

8. “For the discovery of neutrino oscillations, which
shows that neutrinos have mass”
So what is the mass?

9. neutrinos
Created in nuclear
power plants
Created in the sun
Created by the big bang
nasa.gov
wikipedia.org
Known particles

10. ●
Neutrinos interact very weakly
●
Makes measuring their mass difficult
Neutrinos emitted from the sun,
as seen through the earth Super-Kamiokande

11. Source Detector
DetectorSourceBacklight

12. The History of the Universe (backwards)

13. The History of the Universe (forwards)

14. The Planck satellite

18. Cold (-270.3999˚C) Hot (-270.4001˚C)

19. Cold (-270.3999˚C) Hot (-270.4001˚C)

20. DetectorSourceBacklight

21. Summary thus far
• We measure the distortion of the CMB due
to neutrinos released from the big bang to
infer the mass of the neutrino particle
• Our volunteer computers simulate
different hypothetical universes with
different neutrino masses to tell us how
much distortion we would expect, then we
compare to data

22. Outline
• Measuring the mass of the neutrino
particle with Planck
• Cosmology@Home and how Docker has
helped
• Future Docker use at Cosmology@Home
and in the field of physics in general

23. From the user's POV

24. z
http://www.cosmologyathome.org

25. https://boinc.berkeley.edu

30. From our POV

31. Regular apps
• Compile executable for each platform
• Either statically link or include all necessary libraries
• Link against the BOINC libraries and manage user
requests for suspend/checkpoint/resume, etc…
• BOINC takes care of sending it each host, running it, etc...

32. Cosmology@Home computers

33. VM apps
• Just create one VM image, works on all platforms
• BOINC handles suspend/checkpoint/resume
• Still some downsides
– Its clunky to create a VM image
– New app version, user has to redownload whole thing?

34. Cosmology@Home internet connections

35. Docker apps
+Debian base image (~40Mb compressed)
+our app (~3Mb compressed)
BOINC
BOINC Virtualbox wrapper
“boinc2docker” ISO
Docker container
handles pause/resume
generally “BOINC things...”
lightly modified to interact with BOINC

36. Persistence
Logging
Startup script
boot2docker ISO modifications
#!/bin/sh
/etc/init.d/docker stop
tar cf /root/scratch/boinc2docker_persistence.tar /var/lib/docker/*
/etc/init.d/docker start
#!/bin/sh
docker inspect $IMAGE || { docker pull $IMAGE && save_docker.sh; }
docker run --rm -v /root/shared:/root/shared $IMAGE
via Virtualbox guest-logging, logs are uploaded to our DB

37. What running jobs now looks like
• Create the Docker image which runs my
calculation and push to Docker hub
docker build -t cosmohome/mytheory .
docker push cosmohome/mytheory
...
FROM debian:wheezy
RUN apt-get update &&
apt-get -y install libgfortran3 libgomp1 &&
rm -rf /var/lib/apt/lists/*
COPY ["camb", "HighLExtrapTemplate_lenspotentialCls.dat", "/root/"]

38. What running jobs now looks like
• Submit workunit on Cosmology@Home
server pointing to my image
./create_work --app boinc2docker
boinc_app
params
e.g. neutrino mass = X...
A short script like you saw
before which does a
docker run cosmohome/mytheory

39. End result
• Its easy!
• I can spend my time being a physicist,
not a programmer
Previously
Planck

40. Outline
• Measuring the mass of the neutrino
particle with Planck
• Cosmology@Home and how Docker has
helped
• Future Docker use at Cosmology@Home
and in the field of physics in general

41. Docker and volunteer computing

42. “BOINC is the #5
super-computer in
the world. What if
it ran Docker?”
4
2

43. Docker and volunteer computing
Cosmology@Home:
• “Higher fidelity” simulations of the universe
Generally:
• An “IPython Parallel”-like interface to BOINC
• “Service to scientists”
• Swarm, Tutum..?

44. • From the top: the most computer savvy
physicists know of and may use Docker
• From the grassroots: more work needed
– Good news: physicists develop, ship, and
modify code
– Docker and MPI (e.g. see “Shifter” at NERSC)
Docker and scientific computing

45. Summary
• Cosmology@Home, a cluster of volunteer
computers, now runs Docker
• Docker allows us to spend our time being
physicists
• If anyone is looking for open source
projects to contribute to, we welcome
helpers, find me or our
github.com/marius311/cosmohome

46. Thank you!
Marius Millea
mariusmillea@gmail.com