Installing almond to /usr/share/jupyterlab (ie. for all users) doesn't work

[qbouvet]

Hi,

I want to install almond to use it in jupyterlab. I would like to install it for all user. Unfortunately, I can't get it to work.

The issue

I want to install almond it to /usr/share/jupyter/kernels, instead of installing to ~/.local/share/jupyter/kernels/scala for a single user. My other kernels (like python3) are indeed located in /usr/share/jupyter/kernels and work fine. So, I install almond with the following command:

$ sudo coursier launch --fork almond:0.10.9 --scala 2.13.1 -- --install --jupyter-path /usr/share/jupyter/kernels/
>>> ... downloads ...
>>> Installed scala kernel under /usr/share/jupyter/kernels/scala

After that, I can start jupyter-lab and the option to create a scala notebook indeed appears. If I create a notebook, the kernel fails to connect (status "Connecting", then "Disconnected" at the bottom left of the web interface). In the console, I have the following error messages:

[I 2021-01-28 16:47:11.133 ServerApp] Kernel started: b1c696f1-0ac7-4096-8733-21d2c6907b21
Error: class almond.ScalaKernel not found
[I 2021-01-28 16:47:14.135 ServerApp] KernelRestarter: restarting kernel (1/5), new random ports
Error: class almond.ScalaKernel not found
[ ... 4 more times]

What is weird is that almond works perfectly if I install it for one user with:

$ coursier launch --fork almond:0.10.9 --scala 2.13.1 -- --install
>>> Installed scala kernel under $HOME/.local/share/jupyter/kernels/scala

Why does it matter ?

The big picture is that I am trying to fix the almond package for arch linux. When packaging, one must install in /usr/local which is the standard location for packages that all users have access to.

System

Kernel: linux-5.4.92-1-lts
Java: Oracle JDK 11 (also tried with Oracle JDK 8)
Coursier: 2.0.7, JVM version from the AUR (although I also tried with 2.0.9 native version from get-coursier)

---

Could you help me out with this ? Let me know if you need any additional info

Best

[potoo0]

Got some problem.

[potoo0]

Error: class almond.ScalaKernel not found, just because cache path was not specified during installation, so it will use default cache path ~/.cache/coursier/v1, other users will not find the jar in the cache path.

open launcher.jar/coursier/bootstrap/launcher/bootstrap-jar-urls will find:
file:/https/jitpack.io...
...

If we want to install global, must override cache path.

demo:

# create folder for global cache
mkdir /usr/share/coursier/cache
# add to bashrc for all users who want to use kernel
export COURSIER_CACHE=/usr/share/coursier/cache

# install kernel
coursier launch --fork almond:0.10.0 --scala 2.12.11 -- --install --jupyter-path /usr/share/jupyter/kernels/

# change perm for all users who want to use kernel, let's say jupyter group
chgrp -R jupyter /usr/share/coursier
chmod -R g+rwxs /usr/share/coursier

# add kernel read perm for user
chmod -R +r /usr/share/jupyter/kernels/

[tingjhenjiang]

Error: class almond.ScalaKernel not found, just because cache path was not specified during installation, so it will use default cache path ~/.cache/coursier/v1, other users will not find the jar in the cache path.

open launcher.jar/coursier/bootstrap/launcher/bootstrap-jar-urls will find:
file:/https/jitpack.io...
...

If we want to install global, must override cache path.

demo:

# create folder for global cache
mkdir /usr/share/coursier/cache
# add to bashrc for all users who want to use kernel
export COURSIER_CACHE=/usr/share/coursier/cache

# install kernel
coursier launch --fork almond:0.10.0 --scala 2.12.11 -- --install --jupyter-path /usr/share/jupyter/kernels/

# change perm for all users who want to use kernel, let's say jupyter group
chgrp -R jupyter /usr/share/coursier
chmod -R g+rwxs /usr/share/coursier

# add kernel read perm for user
chmod -R +r /usr/share/jupyter/kernels/

I confirmed that this solution works for jupyterhub, conda environments following the jupyterhub installation guide(the difficult way) and the command ./coursier launch --fork almond:0.11.1 --scala 2.13.4 -- --install --id "almond" --jupyter-path "/opt/jupyterhub/share/jupyter/kernels". One must check the correct almond-scala version pairs here.

[qbouvet]

The solution does work. Closing.