This week, Sylabs announced that they will end-of-life SingularityPRO, Singularity Enterprise, and SingularityCE on October 25, 2026, coinciding with the end of their engineering in the SingularityCE project and Singularity ecosystem.
We at CIQ want to recognize and thank Sylabs for concluding their work on SingularityPRO and Singularity Enterprise by releasing as open source functionality previously reserved for their commercial offerings. This is the best way to ensure that these features live on, and I wouldn't be surprised to see them picked up and maintained by the Apptainer community.
Singularity began, as many things have, as one of Gregory Kurtzer's projects at Lawrence Berkeley National Laboratory. At the time (the long, long ago year of 2015), containerization was the hot new thing, and everyone wanted to run Docker on their HPC cluster. But Docker's security model was built for hosting system services, not for multiple users on a shared cluster. Singularity was built for that multi-user use case, allowing anyone to benefit from the growing container ecosystem without needing special privileges. Greg originally founded Sylabs in 2017 to develop Singularity and the growing ecosystem around it.
Singularity was my first experience with containers, too, running an HPC cluster at the University of Colorado Boulder. I had a user who wanted to run an Ubuntu-only application on our Enterprise Linux cluster. I had vaguely heard of this containerization thing before, and I thought it might be a way to solve this researcher's need. I was pleasantly surprised when, only a few hours later, I had a working Ubuntu container with their application built and ready to go as a single SIF image that they could run anywhere in our environment.
Today, containerization has only grown in popularity, underpinning the entire "cloud native" movement, particularly via the Kubernetes ecosystem and the Open Container Initiative, as well as CIQ's own Fuzzball. Containers' pervasive use in multi-tenant environments has made them a frequent target for security research, particularly in this era of AI code analysis. (Interestingly, much of this research has rediscovered the same issue that motivated building Singularity in the first place: that containers aren't really a sufficient privilege boundary.)
In 2021, the Singularity open source project joined the Linux Foundation under its new name, Apptainer. Since then, the Apptainer open source project and community have been led by Dave Dykstra ("Dr. Dave") from Fermi National Accelerator Laboratory, with support from a number of committed contributors in the community (including CIQ). Meanwhile, Sylabs continued their own development of Singularity as SingularityCE, along with their commercial offerings.
While Sylabs has announced the end of their suite of Singularity products, the Apptainer community and project continues on from the original open source foundation. Current Singularity users should feel right at home: Apptainer still provides the singularity command for backwards-compatibility, and it runs the same SIF images. Apptainer is also available from CIQ, including as part of the Warewulf Pro cluster management offering. And for teams that need more than the runtime itself, we've announced Apptainer Pro, which will add long-term support releases, preflight compatibility checks, execution records and cluster image distribution on top of open source Apptainer. We're taking early customers now, with priority for organizations moving from Singularity, with wider availability coming soon.
The Apptainer project has a long life ahead of it, and I'm thankful to Dr. Dave and the rest of the community for all the work they continue to put into developing and maintaining such an important part of our software ecosystem.
If you're interested in getting involved with, or just learning more about, the Apptainer project, you can join the Slack community or mailing list. Or, if you're already a Singularity or Apptainer user and are looking for the assurances of a commercially supported product, take a look at our Apptainer Pro early customer program.
And to everyone at Sylabs: I hope for nothing short of the very best for you in your next endeavor, and we look forward to the next incredible thing you’ll build.
~ Jonathon Anderson
