Charliecloud

What Charliecloud is

Charliecloud is free, open source container software for high performance computing applications on Linux. Its fully unprivileged workflow uses Linux user namespaces to run containers without privileged operations or daemons, with minimal configuration changes on computing center resources. Users can build images, push and pull them to registries, and use accelerators such as GPUs.

The ch-image tool supports registry authentication and works with registries including GitLab Container Registry. For builds, Charliecloud parses Dockerfiles using a formal grammar and uses a layer-free cache based on Git rather than union mount filesystems and tarballs. At runtime, ch-run can inject host resources through the Container Device Interface, including NVIDIA GPUs and Cray networking. Installation options include building from a release tarball or Git checkout, or using package managers such as Spack and Fedora/EPEL. The software is distributed under Apache License, Version 2.0. It requires Linux user namespaces for its unprivileged workflow and has been run on x86-64, ARM, and Power; current testing covers x86_64 and ARM. The project supports only the current release and relies on the Linux kernel and userland for security enforcement.