Café Guix : Reproducible computation using Guix and CWL
Nov 18, 2025
Online
Tuesday, 25 November at 1:00 p.m.
Arun Isaac will be talking to us about workflow and Guix. This event will be held in English and can be accessed via the following link: https://meet.univ-grenoble-alpes.fr/b/cel-dyj-m93-arv.
Abstract : Traditionally, HPC jobs are submitted as bash scripts to a batch
scheduler. These scripts invariably involve specifics of the HPC system,
and are not reproducible. This approach also requires micro-management
and manual bookkeeping of input, output and temporary files—it is not at
the right level of abstraction for scientists thinking about their
science.
Guix, the functional package manager that we love and use, offers strong
reproucibility guarantees and precise tracking of software provenance.
Workflow languages such as the Common Workflow Language (CWL) abstract
away the manual bookkeeping, and provide a description of the workflow
that is easily reproduced on other systems. In addition, CWL being a
specification, it is easy to implement runners that are standards
compliant but run on different execution environments—single machine,
HPC cluster and cloud alike.
In this talk, I will describe and demo a reproducible computational
stack built on ccwl, ravanan and Guix. ccwl, the Concise Common Workflow
Language, is a workflow language that compiles to the Common Workflow
Language. ravanan is a CWL runner that runs on HPC clusters and uses
Guix to facilitate reproducible computation. ravanan caches all
intermediate outputs. And, thanks to Guix’s robust hashing of the entire
dependency tree, ravanan’s cache is guaranteed to never go stale: thus
you never have to recompute any step and never fear that your cache may
be stale.
Café Guix is a monthly informal gathering for discussion about the GNU Guix software environment manager. Students, researchers, system administrators, IT support staff from laboratories or computing centres—everyone is welcome to attend this monthly one-hour meeting, where we discuss questions brought up by participants about Guix and its use in a broad sense.
These webinars usually take place on the last Tuesday of the month from 1 p.m. to 2 p.m. at this link: https://meet.univ-grenoble-alpes.fr/b/cel-dyj-m93-arv. You can view the programme for the coming year (as well as the address of a dedicated Mattermost channel) on the page dedicated to Guix cafés.