VSCode on Triton

VSCode is a text editor and IDE (Integrated Development Environment). It is very popular these days, partly due to it’s good usability.


If you are using on Triton, it’s available as a web app through Open OnDemand, see below.

It can also be installed on your own computer, which might be good to do anyway. If you do this, make sure you turn off telemetry if you don’t want Microsoft to get reports of your activity. Search “telemetry” in settings to check and disable (note that this doesn’t fully turn it off).

VSCodium is an open-source build of VScode (like “chromium” is an open-source build of Google Chrome) that disables all telemetry by default and removes non-open source bits. It is essentially the same thing, but due to Microsoft licenses it can’t use the same extension registry as VSCode. It does have a stand-alone extension registry, though.

Usage warnings

VS Code on clusters have some issues you should avoid. VS Code is still useful, but you need to use it smartly:


  • Only open specific project directories. Don’t open your whole home directory, whole $WRKDIR work directory, or all /scratch/, or any directories with a huge number of files: it will scan all files and use a huge amount of CPU.

  • We recommend against Jupyter computations in VS Code. The kernels won’t stop if your connection ends, and continue to use memory (and possibly CPU). See the below point. The strategies in OOD or interactive jobs” is OK though since it isolates resources.

  • Don’t run heavy computations or use too much memory. It can use up all your allocated resources and prevent other logins (because of how we limit resources per user). If you find you can’t log in, contact us. The strategies in OOD or interactive jobs” is OK though since it isolates resources.

Security and extensions

As always when using user-contributed extensions, be cautious of what extensions you install. A malicious extension can access and/or delete all of the data available via your account.

VSCode through Open OnDemand

See also

Open OnDemand

Update: Not available on Triton since May 2024 (yet), please ask us if this is important to you

VSCode is available through Open OnDemand, and with this you can select whatever resources you want (memory, CPU, etc) and run directly in the Slurm queue. This means you can directly perform calculations in that VSCode session and it runs properly (not on the login node).

This is useful for getting things done quickly or do simple debugging, but running in a web browser can be limited in some cases (interface, lifetime, etc.). Another limitation is OOD VSCode does not support GPU computing.

VSCode remote SSH

“Remote SSH” is a nice way to work on a remote computer and provides both editing and shell access, but everything will run directly on the login node on Triton. This is OK for writing code and editing, but not for main computations (see the section above or below). To repeat: don’t use this for running any big computations.

Screenshot saying "SSH: triton".

If you see this in the lower left corner (or whatever the name of your cluster SSH config is), you are connected to the login node (and again, should not do big calculations). It’s possible the exact look may be different for others.

You can see connection instructions (including screenshots) at the Sigma2 instructions.

VSCode can use a regular OpenSSH configuration file, so you may as well set that up once and it can be used for everything - see SSH for the full story. The basics of SSH to Triton are in Connecting via ssh. A SSH key can allow you to connect without entering a password every time.

VSCode remote SSH host directly to interactive job


Sometimes you want more resources than the login node. This section presents a way to have VSCode directly connect to a job resource allocation on Triton - so you can do larger calculations / use more memory / etc. without interfering with others. Note that for real production calculations, you should use Serial Jobs, and not run stuff through your editor, since everything gets lost when your connection dies.

This section contains original research and may not fully work, and may only work on Linux/Mac right now (but Windows might work too since it uses OpenSSH).

In your ~/.ssh/config, add this block to define a server triton-vscode. For more information .ssh/config, including what these mean and what else you might need in here, see SSH:

Host triton-vscode
    ProxyCommand ssh triton /appl/manual_installations/software/ssh-node-proxycommand --partition=interactive --time=1:00:00
    StrictHostKeyChecking no
    UserKnownHostsFile /dev/null

# You also need a triton alias here:

Host triton
    HostName triton.aalto.fi
    # ... any other thing you need for connecting to triton.

Now, with VSCode’s Remote SSH, you can select the triton-vscode remote. It will ssh to Triton, request a job, and then directly connect to the job. Configure the job requirements in the ProxyCommand line (see Job submission - you can have multiple Host sections for different types of requirements).

Possible issues which may affect usage:

  • If the ssh connection dies, the background job will be terminated. You will lose your state and not be able to save.

  • If the job dies due to time or memory exceeded, the same as above will happen: your job will die and there is no time to save.

  • If you srun from within the job, then it gets messed up because the environment variable SLURM_JOB_ID is set from the interactive job that got started. It’s hard for us to unset this, so if you are using the terminal to srun or sbatch, you should unset SLURM_JOB_ID first. (Note there are many other variables set by Slurm. Make sure that they don’t interfere with jobs you may run from this vscode session).

  • If you request a GPU node or other high resources, this is reserved the whole time even if you aren’t using them. Consider this before reserving large resources (unless you close the jobs soon), or you might get an email from us asking if we can help you improve research usage.