This GitHub Action sets up the European Environment for Scientific Software Installations (EESSI) for use in GitHub Workflows. EESSI is like a streaming service for software installations: you have access to a large catalogue of software provided by EESSI, however the installations are only cached on your system once you try to access them.

You load the software by use of the Lmod implementation of environment modules with commands such as module load CMake. The action also supports the use of direnv, which allows you to define a software environment via a .envrc file inside a directory (i.e., your repository). Coupled with EESSI, this can provide a complete and reproducible build environment for your project without the need for to perform any installations of dependencies. Such a .envrc file might look like:

module purge  # Make sure we are in a clean environment
export FOO=foo  # Export an environment variable that I need when building my project
module load CMake/3.20.1-GCCcore-10.3.0  # Load a dependency of my project (CMake version 3.20.1 built with GCC 10.3.0) 

Another example of a .envrc file can be found in the .envrc included with this repository.

You can use this GitHub Action in a workflow in your own repository with uses: eessi/github-action-eessi@v2.

A minimal job example for GitHub-hosted runners of type ubuntu-latest:

jobs:
  ubuntu-minimal:
    runs-on: ubuntu-latest
    steps:
    - uses: eessi/github-action-eessi@v2
    - name: Test EESSI
      run: |
        module avail
      shell: bash

The following parameters are supported:

• eessi_stack_version: version of the EESSI stack to use (defaults to latest)
• eessi_config_package: location of the EESSI CernVM-FS configuration package (defaults to https://github.com/EESSI/filesystem-layer/releases/download/latest/cvmfs-config-eessi_latest_all.deb).

The following minimal example, which is similar to a workflow in this repository at .github/workflows/minimal-usage.yml, sets up EESSI and initiates the stack.

name: Minimal usage
on: [push, pull_request]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: eessi/github-action-eessi@v2
    - name: Test EESSI
      run: |
        module avail
      shell: bash

This GitHub Action installs the EESSI software stack, making it available to subsequent bash commands. This means one can create workflows such as:

name: GROMACS usage
on: [push, pull_request]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: eessi/github-action-eessi@v2
    - name: Test EESSI
      run: |
        module load GROMACS
        gmx --version
      shell: bash

where the gmx command was only available to run after the loading the necessary environment module GROMACS. Note that I have not given the version of GROMACS which means the latest available version will be loaded.

In order to trigger the initialisation of the EESSI environment and direnv, we leverage the environment variable BASH_ENV. As a result, this action is (currently) only supported with a bash shell.

This GitHub Action is only expected to work in workflows that run on ubuntu. This currently excludes the windows and macOS targets.

This GitHub Action leverages cvmfs-contrib/github-action-cvmfs to set up the CernVM File System which acts as our distribution layer. The available software packages are limited by what we distribute, user input for extensions to this set can be provided by opening an issue at https://github.com/EESSI/software-layer.

In case your workflow uses docker containers, the cvmfs directory can be mounted inside the container by using the flag -v /cvmfs:/cvmfs:shared. You may also need to pass through the BASH_ENV variable using the flag -e BASH_ENV.