Feedback on Docker Image Provided

Dear ROOT Developers,

  1. I would like to use the Docker Image you provide to use it with pyROOT Unfortunately, if I launch the image, I am inside the ROOT shell immediately. If I try to exit (.q), the Docker Image is closed. Is there a way to use it for testing pyROOT files?

  2. Further, the Docker images are not tagged. Would you mind adding such a feature? I think this would be very helpful to be able to also go back to other versions.

  3. I tried to build my own Docker image of ROOT 6.18 basing it on Ubuntu. I get following error when compiling ROOT:

CMake Error at cmake/modules/SearchInstalledSoftware.cmake:830 (message):
  Alien API not found and is required.  Set the variable ALIEN_DIR to point
  to your Alien installation,or include the installation of Alien in the
Call Stack (most recent call first):
  CMakeLists.txt:159 (include)

Do you have an idea what the issue might be?

Please find the Dockerfile and packages I used attached.

Dockerfile.txt (1.3 KB) packages.txt (642 Bytes)

Coming back to point 1. I managed to run the image without entering ROOT via

sudo docker run -it --entrypoint=/bin/bash  rootproject/root:latest

However, if I then do

$ python
>>> from ROOT import RDataFrame
Error in <TCling::RegisterModule>: cannot find dictionary module libPyROOT_rdict.pcm

Is there something I can do to use pyROOT?

  1. You already found out, but you can just run sudo docker run -it rootproject/root bash to enter the image in a regular shell.
  2. We have no control over which version is officially packaged in Fedora, which is the distribution the official image is currently based. Ubuntu doesn’t have ROOT packaged officially, unfortunately. We are going to get the other images in automated as well eventually, and add images with tagged versions of ROOT compiled from source, so that will make it easier for you to test.
  3. That’s probably due to having -Dall=ON -Dfail-on-missing=ON in the configuration. Just add options to disable the things that fail (-Dalien=OFF in the case above), and you will be able to continue.


thank you for the reply! Concerning

  1. As mentioned above, I get following error when doing as you propose with Docker
    $ python
    >>> from ROOT import RDataFrame
    Error in <TCling::RegisterModule>: cannot find dictionary module libPyROOT_rdict.pcm
    Is there any solution or workaround to avoid the error?
  2. Sorry, I was not being clear. I meant tagging the ROOT version, not the Fedora one. As far as I can tell, this is not done right now.
  3. Thank you, that was helpful. I had to change a couple of other parameters ( -Dcuda=OFF, -Dvecgeom=OFF,-Dtmva-gpu=OFF, -Dqt5web=OFF), too. It’s compiling now.
  1. Sure, I will add tagged images at some point. Fedora only has 6.16 and 6.18 at the moment, though. I may have to go to older Fedora versions for older releases of ROOT. Which versions are you interested in? You can also go back to ROOT 6.16 with the current image by calling
# yum downgrade --allowerasing root-6.16.00


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This is now fixed in Fedora, and therefore in the official docker image of ROOT. Cheers,