Jupyter on Triton


Quick link

Triton’s Jupyter is available via Open OnDemand, https://ondemand.triton.aalto.fi (Jupyter app).


For new users

Are you new to Triton and want to access Jupyter? Triton is a high-performance computing cluster, and JupyterHub is just one of our services - one of the easiest ways to get started. You still need a Triton account. This site has many instructions, but you should read at least:

If you want to use Triton more, you should finish the entire tutorials section.

Jupyter notebooks are a way of interactive, web-based computing: instead of either scripts or interactive shells, the notebooks allow you to see a whole script + output and experiment interactively and visually. They are good for developing and testing things, but once things work and you need to scale up, it is best to put your code into proper programs (more info). You must do this if you are going to large parallel computing.

Triton’s standard Jupyter environment is available at https://ondemand.triton.aalto.fi (the Jupyter app).

You can always run notebooks yourself on your own (or remote) computers, but on Triton we have some facilities already set up to make it easier.

How Jupyter notebooks work

  • Start a notebook

  • Enter some code into a cell.

  • Run it with the buttons or Control-enter or Shift-enter to run a cell.

  • Edit/create new cells, run again. Repeat indefinitely.

  • You have a visual history of what you have run, with code and results nicely interspersed. With certain languages such as Python, you can plots and other things embedded, so that it becomes a complete reproducible story.

JupyterLab is the next iteration of this and has many more features, making it closer to an IDE or RStudio.

Notebooks are without a doubt a great tool. However, they are only one tool, and you need to know their limitations. See our other page on limitations of notebooks.

Jupyter via Open OnDemand


JupyterHub is replaced by Open OnDemand (OOD) since 2024 April. The “Jupyter” app has been set up to reproduce the previous general-use Jupyter environment.

Connecting and starting

Log in to Open OnDemand: https://ondemand.triton.aalto.fi.

Once you log in, select the Jupyter app. Then, you must start your single-user server. Your server runs in the Slurm queue, so the first start-up takes a few seconds but after that it will stay running even if you log out.

The resources you request are managed by slurm: if you go over the memory limit, your server will be killed without warning or notification (but you can see it in the output log, output.log in the session). The Jupyter server nodes are oversubscribed, which means that we can allocate more memory and CPU than is actually available. We will monitor the nodes to try to ensure that there are enough resources available, so do report problems to us. Please request the minimum amount of memory you think you need - you can always restart with more memory. You can go over your memory request a little bit before you get problems. When you use Jupyter via this interface, the slurm billing weights are lower, so that the rest of your Triton priority does not decrease by as much.


Once you get to your single-user server Jupyter running as your own user on Triton. You begin in a convenience directory which has links to home, scratch, etc. You can not make files in this directory (it is read-only), but you can navigate to the other folders to create your notebooks. You have access to all the Triton filesystems (not project/archive) and all normal software.

The log files for your single-user servers can be found in the OOD session directory, see output.log.

For reasons of web security, you can’t install your own extensions (but you can install your own kernels). Send your requests to us instead.

Software and kernels

A Jupyter Kernel is the runtime which actually executes the code in the notebook (and it is separate from Jupyter itself). We have various kernels automatically installed:

  • Python (module scicomp-python-env)

  • Matlab (latest module)

  • Bash kernel

  • R (a default R environment you can get by module load scicomp-r-env. (“R (safe)” is similar but tries to block some local user configuration which sometimes breaks things, see FAQ for more hints.)

  • Kernels (and software in kernels) may be updated over time - create your own environment for reproducibility.

Since these are the normal Triton modules, you can submit installation requests for software in these so that it is automatically available.

Installing kernels from virtualenvs or Anaconda environments

If you want to use Jupyter with your own packages, you can do that. First, make a conda environment / virtual environment on Triton and install the software you need in it (see The scicomp python env and conda environments or Python: virtualenv). This environment can be used for other things, such as your own development outside of Jupyter.

You have to have the package ipykernel installed in the environment: Add it to your requirements/environment, or activate the environment and do pip install ipykernel.

Then, you need to make the environment visible inside of Jupyter. For conda environments, you can do:

$ module load jupyterhub/live
$ envkernel conda --user --name INTERNAL_NAME --display-name="My conda" /path/to/conda_env

Or for Python virtualenvs:

$ module load jupyterhub/live
$ envkernel virtualenv --user --name INTERNAL_NAME --display-name="My virtualenv" /path/to/virtualenv

Installing a different R module as a kernel

Load your R modules, install R kernel normally (to some NAME), use envkernel as a wrapper to re-write the kernel (reading the NAME and rewriting to the same NAME), after it loads the modules you need:

## Load jupyterhub/live, and R 3.6.1 with IRkernel.
$ module load r-irkernel/1.1-python3
$ module load jupyterhub/live

## Use Rscript to install jupyter kernel
$ Rscript -e "library(IRkernel); IRkernel::installspec(name='NAME', displayname='R 3.6.1')"

## Use envkernel to re-write, loading the R modules.
$ envkernel lmod --user --kernel-template=NAME --name=NAME $CONDA_PREFIX r-irkernel/1.1-python3

Installing a different R version as a kernel

There are two ways to install a different R version kernel for jupyter. One relies on you building your own conda environment. The disadvantage is that you will need to create a kernel, the advantage is that you can add additional packages. The other option is to use the existing R installations on Triton.

You will need to create your own conda environment with all packages that are necessary to deploy the environment as a kernel.:

## Load mamba module before creating your environment - this provides mamba that is used to create your environment
$ module load mamba

Create your conda environment, selecting a NAME for the environment.:

## This will use the latest R version on conda-forge. If you need a specific version you can specify it
## as r-essentials=X.X.X, where X.X.X is your required R version number
$ mamba create -n ENVNAME -c conda-forge r-essentials r-irkernel
## If Mamba doesn't work you can also replace it with conda, but usually mamba is a lot faster

The next steps are the same as building a Kernel, except for activating the environment instead of loading the r-irkernel module, since this module depends on the R version. the displayname will be what will be displayed on jupyter

## Use Rscript to install jupyter kernel, you need the environment for this.
## You need the Python `jupyter` command so R can know the right place to
## install the kernel (provided by jupyterhub/live)
$ module load jupyterhub/live
$ source activate ENVNAME
$ Rscript -e "library(IRkernel); IRkernel::installspec(name='ir-NAME', displayname='YOUR R Version')"
$ conda deactivate ENVNAME

## For R versions before 4, you need to install the kernel. After version 4 IRkernel automatically installs it.
$ envkernel conda --user --kernel-template=ir-NAME --name=ir-NAME ENVNAME    TODO: full path?


Installing R packages for jupyter

Installing packages via jupyter can be problematic, as they require interactivity, which jupyter does not readily support. To install packages therefore go directly to triton. Load the environment or R module you use and install the packages ineractively. After that is done, restart your jupyter session and reload your kernel, all packages that you installed should then be available.

Install your own kernels from other Python modules

This works if the module provides the command python and ipykernel is installed. This has to be done once in any Triton shell:

$ module load jupyterhub/live
$ envkernel lmod --user --name INTERNAL_NAME --display-name="Python from my module" MODULE_NAME
$ module purge

Install your own kernels from Singularity image

First, find the .simg file name. If you are using this from one of the Triton modules, you can use module show MODULE_NAME and look for SING_IMAGE in the output.

Then, install a kernel for your own user using envkernel. This has to be done once in any Triton shell:

$ module load jupyterhub/live
$ envkernel singularity --user --name KERNEL_NAME --display-name="Singularity my kernel" SIMG_IMAGE
$ module purge

As with the above, the image has to provide a python command and have ipykernel installed (assuming you want to use Python, other kernels have different requirements).


Julia: currently doesn’t seem to play nicely with global installations (so we can’t install it for you, if anyone knows something otherwise, let us know). Roughly, these steps should work to install the kernel yourself:

$ module load julia
$ module load jupyterhub/live
$ julia
julia> Pkg.add("IJulia")

If this doesn’t work, it may think it is already installed. Force it with this:

julia> using IJulia
julia> installkernel("julia")

Install your own non-Python kernels

  • First, module load jupyterhub/live. This loads the conda environment which contains all the server code and configuration. (This step may not be needed for all kernels)

  • Follow the instructions you find for your kernel. You may need to specify --user or some such to have it install in your user directory.

  • You can check your own kernels in ~/.local/share/jupyter/kernels/.

If your kernel involves loading a module, you can either a) load the modules within the notebook server (“softwares” tab in the menu), or b) update your kernel.json to include the required environment variables (see kernelspec). (We need to do some work to figure out just how this works). Check /appl/manual_installations/software/jupyterhub/live/miniconda/share/jupyter/kernels/ir/kernel.json for an example of a kernel that loads a module first.

From Jupyter notebooks to running on the queue

While jupyter is great to interactively run code, it can become a problem if you need to run multiple parameter sets through a jupyter notebook or you need a specific resource which is not available for jupyter. The latter might be because the resource is sparse enough that having an open jupyter session that finished a part and is waiting for the user to start the next is idly blocking the resource. At this point you will likely want to move your code to pure python and run it via the queue.

Here are the steps necessary to do so:

  1. Log into Triton via ssh ( Tutorials can be found here and here ).

  2. In the resulting terminal session, load the jupyterhub module to have jupyter available ( module load jupyterhub )

  3. Navigate to the folder where your jupyter notebooks are located. You can see the path by moving your mouse over the files tab on jupyterlab.

  4. Convert the notebook(s) you want to run on the cluster ( jupyter nbconvert yourScriptName.ipynb --to python).

    • If you need to run your code for multiple different parameters, modify the python code to allow input parameter parsing (e.g. using argparse, or docopt ) You should include both input and output arguments as you want to save files to different result folders or have them have indicative filenames. There are two main reasons for this approach: A) it makes your code more maintainable, since you don’t need to modify the code when changing parameters and B) you are less likely to use the wrong version of your code (and thus getting the wrong results).

  5. (Optional) Set up a conda environment. This is mainly necessary if you have multiple conda or pip installable packages that are required for your job and which are not part of the normal Sc module. Try it via module load scicomp-python-env. You can’t install into the scicomp environment provided by the scicomp-python-env module and you should NOT use pip install --user as it will bite you later (and can cause difficult to debug problems). If you need to set up your own environment follow this guide

  6. Set up a slurm batch script in a file e.g. simple_python_gpu.sh. You can do this either with nano simple_python_gpu.sh (to save the file press ctrl+x, type y to save the file and press Enter to accept the file name), or you can mount the triton file system and use your favorite editor, for guides on how to mount the file system have a look here and here). Depending on your OS, it might be difficult to mount home and it is anyways best practice to use /scratch/work/USERNAME for your code. Here is an example:

    #SBATCH --cpus-per-task 1       # The number of CPUs your code can use, if in doubt, use 1 for CPU only code or 6 if you run on GPUs (since code running on GPUs commonly allows parallelization of data provision to the GPU)
    #SBATCH --mem 10G               # The amount of memory you expect your code to need. Format is 10G for 10 Gigabyte, 500M for 500 Megabyte etc
    #SBATCH --time=01:00:00         # Time in HH:MM:SS or DD-HH of your job. the maximum is 120 hours or 5 days.
    #SBATCH --gres=gpu:1            # Additional specific ressources can be requested via gres. Mainly used for requesting GPUs format is: gres=RessourceType:Number
    module load python-scicomp-env  # or `module load mamba` if you use your own environment.
    source activate yourEnvironment # if you use your own environment
    python yourScriptName.py ARG    

    This is a minimalistic example. If you have parameter sets that you want to use have a look at array jobs here)

  7. Submit your batch script to the queue : sbatch simple_python_gpu.sh This call will print a message like: Submitted batch job <jobid> You can use e.g. slurm q to see your current jobs and their status in the queue, or monitor your jobs as described here.

Git integration

You can enable git integration on Triton by using the following lines from inside a git repository. (This is normal nbdime, but uses the centrally installed one so that you don’t have to load a particular conda environment first. The sed command fixes relative paths to absolute paths, so that you use the tools no matter what modules you have loaded):

$ /appl/manual_installations/software/jupyterhub/live/miniconda/bin/nbdime config-git --enable
$ sed --in-place -r 's@(= )[ a-z/-]*(git-nb)@\1/appl/manual_installations/software/jupyterhub/live/miniconda/bin/\2@' .git/config

FAQ/common problems

  • My server has died mysteriously. This may happen if resource usage becomes too much and exceed the limits - Slurm will kill your notebook. You can check the output.log file in the OOD session directory.

  • My R kernel keeps dying. Some people seem to have global R configuration, either in .bashrc or .Renviron or some such which globally, which even affects the R kernel here. Things we have seen: pre-loading modules in .bashrc which conflict with the kernel R module; changing RLIBS in .Renviron. You can either (temporarily or permanently) remove these changes, or you could install your own R kernel. If you install your own, it is up to you to maintain it (and remember that you installed it).

See also

Our configuration is available on Github. Theoretically, all the pieces are here but it is not yet documented well and not yet generalizable. The Ansible role is a good start but the jupyterhub config and setup is hackish.