Charliecloud vs LXD

Charliecloud is free, open-source container software for high-performance computing on Linux. It runs containers without privileged operations or daemons by using Linux user namespaces, with minimal configuration changes on computing-center resources. Users can build images, push and pull them to registries, and use accelerators such as GPUs. Its layer-free build cache is based on Git rather than union-mount filesystems and tarballs, and Dockerfiles are parsed with a formal grammar. The ch-image tool supports registry authentication and registries including GitLab Container Registry. At runtime, ch-run can inject host resources through the Container Device Interface, including NVIDIA GPUs and Cray networking. Installation is available from a release tarball, Git checkout, Spack, or Fedora/EPEL. Charliecloud requires Linux user namespaces and has been run on x86-64, ARM, and Power; current testing covers x86_64 and ARM. It is distributed under Apache License, Version 2.0. The project supports only the current release and provides no internal security boundary.

LXD is an open-source platform for managing system containers and virtual machines on Linux. It brings LXC-based containers and KVM-based virtual machines together, with images for many Linux distributions and Windows virtual machines. Management options include a command line, REST API, web UI and third-party tools; the same HTTP API supports local and remote access. An official web UI is available by default starting with LXD 5.21.0 LTS. Features include resource limits, scheduled and expiring snapshots, projects, hardware passthrough, live migration and advanced networking. Containers run unprivileged by default, and virtual machines support UEFI Secure Boot and vTPM. LXD can run from a laptop to a data-center deployment; documentation describes clusters of up to 50 servers with thousands of instances. LXD is free, with the open-source plan listed at free. Ubuntu Pro Personal is also free for up to five physical Ubuntu systems. Enterprise workstation and server subscriptions are $25 a year and $500 a year, respectively.