Open OnDemand

Published

December 16, 2025

What it is

Open OnDemand (OOD) is a browser-based portal for launching interactive sessions on ADA without local SSH setup. It provides web terminals, a file browser, and ready-made apps such as RStudio, JupyterLab, and VS Code.

  • Portal: https://ondemand.labs.vu.nl
  • Access: available on campus or via the VU VPN.
  • Scheduler: all sessions run as SLURM jobs on compute nodes.

Resources and persistence

ImportantChoose resources explicitly

For every session you must request resources: partition, CPUs, memory, and walltime. The scheduler will start your app when suitable nodes are available.

  • Sessions keep running until the requested walltime expires, even if you close the browser tab or switch computers. Reconnect from “My Interactive Sessions”.
  • Please stop sessions when finished to free resources for others.

System apps (RStudio, JupyterLab, VS Code)

  1. Open the OOD portal and click the app icon (for example RStudio, JupyterLab, or VS Code).
  2. Fill in the resource form: partition/queue, CPUs, memory, walltime (and any optional parameters).
  3. Click “Launch”. OOD submits a job; when it starts, click “Connect”.
  4. Return later via “My Interactive Sessions” to reconnect, or “Stop” to end early.

Notes:

  • File access mirrors your cluster home and project storage.
  • If a session stays queued, reduce resources or select another partition; consult the SLURM page for tips.

Custom software via Apptainer (optional)

If you need a custom RStudio Server or JupyterLab environment, package it as an Apptainer (.sif) image and point the app to your image at launch.

  • Build the image locally or on ADA (compute nodes) following the Apptainer docs and our container guidance: see Apptainer Containers.

  • In the OOD app form, select the Apptainer image” option and browse to your .sif in your home directory.

  • Test the image on a compute node before using it in OOD:

    apptainer exec /path/to/your.sif jupyter-lab --version

References: - Apptainer quick start: https://apptainer.org/docs/user/main/quick_start.html

Develop your own OOD apps (advanced)

User app development is enabled. You can create and publish your own interactive apps for your projects.

  • Follow the official guide: https://osc.github.io/ood-documentation/latest/
  • For inspiration, inspect the definitions of the system apps installed on ADA. These are located on the inter04 node under /var/www/ood/apps/sys/ path (jupyter and rstudio_server folders).
WarningNo app requests

We do not build or maintain user-specific OOD apps. You are responsible for your app definitions and containers.

Troubleshooting

  • Session stuck in “Queued/Pending”: your request doesn’t fit current availability. Try a different partition or smaller CPU/memory/walltime; see SLURM.
  • Session reports errors: open the job output/logs from the session card, and include those when requesting help.
  • Need to reconnect: go to “My Interactive Sessions” and click “Connect”. Sessions persist until walltime.