Jupyter - problems with dotnet-try

Since .NET Try supports F# officially I wanted to switch over my Jupyter notebook instance to use that instead of IFsharp. But I ran into a couple of frustrating issues that I wanted to document in case anyone else hit them and didn't know how to debug the issue.

Issue 1. dotnet-try installs but isn't usable

I followed Scott Hanselman's instructions to install dotnet-try, but when I tried to execute dotnet try jupyter install it seemed as though dotnet-try wasn't installed at all:

$ dotnet tool install dotnet-try --global
You can invoke the tool using the following command: dotnet-try
Tool 'dotnet-try' (version '1.0.19553.4') was successfully installed.

$ dotnet try jupyter install
Could not execute because the specified command or file was not found.
Possible reasons for this include:
  * You misspelled a built-in dotnet command.
  * You intended to execute a .NET Core program, but dotnet-try does not exist.
  * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.

After a lot of head scratching I dug into the actual docs and learned that both .NET Core 3.0 and .NET Core 2.1 SDKs should be installed, while I only had .NET Core 3.1's SDK So after a quick sudo apt install dotnet-sdk-3.0 dotnet-sdk-2.1 I was successfully able to install the kernel and list it:

$ jupyter kernelspec list
Available kernels:
  .net-csharp    /home/notebook/.local/share/jupyter/kernels/.net-csharp
  .net-fsharp    /home/notebook/.local/share/jupyter/kernels/.net-fsharp
  mit-scheme     /usr/local/share/jupyter/kernels/mit-scheme
  python3        /usr/local/share/jupyter/kernels/python3

Issue 2. Jupyter can't run dotnet-try

However even though it was installed, each time I tried to create a new F# notebook Jupyter would give an error saying that it was unable to connect to the kernel. After taking a quick look at my logs I saw the same error as before!

Feb 09 13:19:11 aviemore jupyter[837]: [I 13:19:11.169 NotebookApp] KernelRestarter: restarting kernel (1/5), new random ports
Feb 09 13:19:11 aviemore jupyter[837]: Could not execute because the specified command or file was not found.
Feb 09 13:19:11 aviemore jupyter[837]: Possible reasons for this include:
Feb 09 13:19:11 aviemore jupyter[837]: * You misspelled a built-in dotnet command.
Feb 09 13:19:11 aviemore jupyter[837]: * You intended to execute a .NET Core program, but dotnet-try does not exist.
Feb 09 13:19:11 aviemore jupyter[837]: * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.
Feb 09 13:19:14 aviemore jupyter[837]: [I 13:19:14.180 NotebookApp] KernelRestarter: restarting kernel (2/5), new random ports
Feb 09 13:19:14 aviemore jupyter[837]: Could not execute because the specified command or file was not found.
Feb 09 13:19:14 aviemore jupyter[837]: Possible reasons for this include:
Feb 09 13:19:14 aviemore jupyter[837]: * You misspelled a built-in dotnet command.
Feb 09 13:19:14 aviemore jupyter[837]: * You intended to execute a .NET Core program, but dotnet-try does not exist.
Feb 09 13:19:14 aviemore jupyter[837]: * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.

I restarted the service, the server, checked and it took a while to realise the root cause. What happened was, even though dotnet-try was in PATH when I switched over to my jupyter use, it wasn't the case when I ran it via systemd. It seems that /etc/profile - which runs all the scripts in /etc/profile.d, one of which adds the ~/.dotnet/tools dir to PATH - is not used when systemd starts the service. I don't know the correct way to address this, but I wrote a quick script to setup PATH correctly and added an EnvironmentFile to the [Service] section my notebook.service file to use it:

EnvironmentFile=/home/jupyter/config/notebook-config

After I set this up and restarted notebook.service it was able to access dotnet-try and spin up the F# kernel correctly.