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gssi-training

VSC training: Getting Scientific Software Installed

European Environment for Scientific Software Installations (EESSI)

This exercise aims to give you hands-on experience with the European Environment of Scientific Software Installations (EESSI). EESSI can be used as a central software stack on HPC but also as a software stack on your laptop or in the cloud. The exercises indicated with recomended should approximately take 30 minutes to complete. For people interested in other scenarios they can follow the links to other trainings and the EESSI documentation.

relevant links:

Using EESSI

In the following excercise we will show how to check whether EESSI is available on the system. And how to start using it.

# Check if EESSI is available
ls /cvmfs/software.eessi.io

This will return the following on all systems at VSC sites.

README.eessi  host_injections  init  versions

If EESSI is on the system you can initialize the EESSI environment.

source /cvmfs/software.eessi.io/versions/2025.06/init/lmod/bash

If you are on another system and you get the following return. EESSI is not available and you should follow the instructions below.

ls: /cvmfs/software.eessi.io: No such file or directory

EESSI not available

If EESSI is not available on the system you want to use it on their are a number of options. If you have root permissions on the system you can do a native installation of CernVM-FS, which is the delivery machanism for software in EESSI. If you do not have root permissions you can also use cvmfsexec or a container.

Check out the EESSI documentation for the different instructions on making EESSI available:

Excercise

EESSI already has a wide range of software available over its 3 supported versions (2023.06, 2025.06 and 2026.06). You can look at the EESSI software overview page to see if the software and specific version you require is already available. You can also use the module command once EESSI is inatialized.

To get access to different EESSI versions you can run:

module purge
module load EESSI/2025.06

EESSI provides a number of demo’s for software that is already available in the stack. Feel free to run any of the scripts in the demo repository. Below we will go through the steps of running the tblite example.

git clone https://github.com/EESSI/eessi-demo.git
module purge
module load EESSI/2025.06
cd eessi-demo
cd tblite
./run.sh
   --------------------------------------------------------------
   Cycle       total energy       energy error     density error 
   --------------------------------------------------------------
       1    -31.30086746450     -3.1478794E+01     3.3527172E-01
   ...
      18   -31.716155889120     -1.8267450E-09     1.5041592E-05
   --------------------------------------------------------------
   Total:                        0.074 sec
   -31.71658891203904

Building on top of EESSI

If the software you require is not yet in EESSI you can relly on the already existing software stack and build on top of it with EasyBuild, Python venv, spack, … For instructions:

Contributing to EESSI

If you want your software to be available on wide range of systems and it is not yet in EESSI, You can contribute it yourself, see Overview of adding software to EESSI.