TL;DR: The general availability release of Singularity 3.2 has been issued here; it includes significant enhancements to the software – from a plugin framework and support for multistage builds, to enhancements elsewhere in the container ecosystem.  

About a month ago, we announced the availability of the first release candidate for Singularity 3.2. Because our April 12, 2019 post provided the details, we’re only offering a brief summary here of the new features and functionalities that are now generally available:

• Plugin Framework – Designed to ensure that it is extensible and customizable in a modular, effective, and efficient way, this implementation of Singularity provides a basic framework for creating and managing plugins. Through a new command group, plugins can be compiled, installed/uninstalled, enabled/disabled, listed, and inspected. For a demonstration of the plugin framework, we encourage you to view Michael Bauer’s talk here or below from the March 2019 inaugural meeting of the Singularity User Group (SUG).
• Multistage Builds – Purpose-built, lean containers result from the use of Singularity definition files with support for multistage builds. The most sensible way to create and maintain images for use by Singularity now benefits from the ability to leverage multiple container base images from a single definition file. For a representative example, and pointers to additional details, please review our post from April here.
• Ecosystem Support – Endpoints such as the Sylabs Cloud Container LIbrary, and cryptographic keys employed to sign and verify Singularity Image Format (SIF) files, can each be managed via new command groups.

From harmonizing the macOS-specific enhancements with the existing Singularity code base, to the preservation of preexisting Open Containers Initiative (OCI) configuration data (“config.json”) within a SIF file, various additional enhancements complete this release.

The GA release of Singularity 3.2 can be cloned from the project’s GitHub repository. We look forward to your feedback on this release – especially with respect to the new features and functionalities it delivers!

Michael Bauer’s SUG talk on plugin support in Singularity 3.2 is available below and here.