OSs

These apps are lightweight apptainer containers designed for specific use cases. Within these containers, users can obtain root permissions to install their own software, though they cannot access software pre-installed on the cluster. Typical applications include (but are not limited to):

• Installing specialized software not easily available on the cluster
• Working in a fully isolated environment
• Ensuring future reproducibility of your work

At the moment, we support two versions of Ubuntu LTS: 22.04 and 24.04. Below, we outline the procedure of working with one (24.04) on the cluster. The same procedure exactly applies for the other version.

Submitting an OS job

Most fields in the OS form are identical to those in other apps. You must select your desired partition (choose the short partition if you need internet access or plan to install software) and the required resources.

If this is your first submission, you need a persistence overlay file system (hereafter image for simplicity) and will see:

which you should select "Yes". Then you need to specify a name for your image according to the designated pattern. We call it ubuntu2404-splash.img, sine we want to use it as an example.

Finally, you need to specify a size for your image.

Press the Launch button. After a while the "Launch Ubuntu 24.04" button should be appeared. Notice since a 1 GB image is being created in your blkdir, it may take longer than usual for the final launch button to appear.

Installing software inside the OS

We now proceed to install multiple software packages in the container image generated in the previous step.

Example: Installing Splash

• Open a terminal in the session and run the following commands:

  apt update
  apt install splash
  

• It tells you ~ 5 MB disk space you need. This value is important and must be lower than the image size you had specified (1 GB in this case), otherwise you will encounter errors.

• OK! Let’s proceed with pressing y.

• Splash should be installed, now.

You can keep using this session if you still need internet access or if the time and resource limits of the short partition are sufficient for your work. However, before this session ends, you must save any changes you’ve made to the container file system.

Saving your changes

Currently, the OS app is designed so that when you log out of the session, all changes to the file system, including:

• Software installed via apt,
• Changes to system paths like /opt, /etc, or /usr

will be saved to the image created when the job started (see above) in your blkdir. This does not include what you've created or modified in you home, wrkdir and blkdir directories, as they are in your cluster storage.

Data lost

To ensure your changes are saved, you must log out properly. Otherwise, all unsaved system changes will be lost.

Do not cancel your job

When you log out of the session, the system begins saving your image. Please:

• Wait until the job status shows "Completed"
• Do not cancel the job during this time

Re-using your image

Most of the time, you’ll likely need more resources and a longer time limit than what the short partition offers. In such cases, you should run your image in a more suitable partition. Here’s how to use your ubuntu2404-splash image:

Select the Ubuntu 24.04 app from the Interactive Apps menu. Then in the form, choose your desired partition, computation resources and time limit.

Since you don’t need to create a new image, select No when prompted, as shown below:

Select your desired image you had created between the existing ones from the drop-down menu and launch.

Launch your app when it becomes ready.

Let's test Splash on an astrophysical simulation output and see the results.