Create custom kernel for Jupyter Hub

This is how you can setup your JLab jupyterhub notebook to run inside a python virtual environment. This is useful for installing python packages via pip from your own account without needing admin privliges (which you don't have). The following will need to be run from a terminal on a CUE computer. I recommend doing this via a terminal launched via jupyterhub since you can use a python version available there that should have all necessary system libraries installed.

• The JLab firewall will prevent pip from downloading packages using default options. The easiest thing to do is setup a pip configuration file in the home directory of your CUE account that sets the necessary options so you don't have to type them with every pip command. Create a file named "~/.config/pip/pip.conf" and write the following into it:
;
; Options to allow pip install to work from behind
; the hallgw firewall
;

[install]
trusted-host =
pypi.org
files.pythonhosted.org

[search]
trusted-host =
pypi.org
files.pythonhosted.org

• NOTE: To create a venv that works with jupyterhub you must use the /opt/conda/bin/python3.7 version and NOT the one installed in /apps. This directory is not available on the ifarms so you must execute the commands below in a terminal launched in jupyterhub itself. However, if you wish to run the same code on the ifarm machines (including sciml machines) and jupyterhub, then you can obtain a mirrored version of your venv on jupyterhub by following the steps shown at the bottom of this tutorial in Optional section.
• In order to use GPUs with your custom kernel, you need to follow steps shown in the Advance section below.
• Create a python virtual environment in the directory of your choosing with:
/opt/conda/bin/python3.7 -m venv venv
• Source the new environment so it will be used for all subsequent pip commands:
source venv/bin/activate.csh
• Upgrade the pip package itself to see that everything is working:
pip install --upgrade pip
• Install python packages you want:
pip install tensorflow keras pandas matplotlib
• Install the ipykernel into the venv and the venv into your list of kernels:
pip install ipykernel
python -m ipykernel install --user --name=venv
• At this point a new option for "venv" should be there in your launcher for both "Notebook" and "Console".
• The virtual environment is now part of a "kernel" and you can switch existing notebooks to using it via a menu in the upper right-hand corner of the notebook. (you may need to close and reopen the notebook to see the new kernel in the menu)
• You can list available kernels via command line using "jupyter kernelspec list"
• You can remove an old kernels using "jupyter kernelspec uninstall old-kernel"
• Note: We have not tested these steps with different systems and we do not provide support for custom kernels.

• Activate your venv on ifarm and run the following command to save requirements.txt to your home directory.
pip freeze > ~/requirements.txt
• Now in jupyterhub terminal, activate your custom kernel virtual environment and run following command to install all the same set of libraries with exact version numbers in the kernel.
pip install -r ~/requirements.txt
Advance: To use GPUs with your custom kernel, go to ~/.local/share/jupyter/kernels/venv. Inside this directory there's a file named kernel.json that must look like as follows, please add env variable to this as highlighted below. NOTE: currently, jupyterhub only supports cuda 10 (compatible with tf 2.3.x).
{
"argv":[
"< path to the python source >",
"-m",
"ipykernel_launcher",
"-f",
"{Connection_file}",
],
"display_name": "venv",
"language": "python",

"env": {"LD_LIBRARY_PATH":"/apps/cuda/10.1/lib64:/usr/local/lib:/.singularity.d/libs"}

}