Best of Bootc

Red Hat dedicated an episode of Into the Terminal to bootable containers. Episode 202, Bootable Container Fundamentals (bootc), walks through the whole loop an engineer needs to get started: building a bootable container image, authenticating to a registry, deploying, and then updating and rolling back.

Reading and Watching

• bootc and overlays: the r/silverblue community discusses deriving an image as the replacement for layering with rpm-ostree once Silverblue moves to bootc.
• Amutable Foundations: A Technical Overview: Lennart Poettering, Michael Vogt and Joaquim Rocha describe an image-based OS assembled from a handful of signed EROFS/dm-verity disk images, combined with sysext and confext and built from Fedora packages, with a control plane to update and verify a fleet. Not bootc, but a neighboring design worth following.

Community Builds

• deskos-ubuntu-bootc: DeskOS is filling the gap left by the lack of official bootc images from Ubuntu by offering a 26.04 image with GNOME. This is a great place to start for anyone who wants to build on bootc without leaving Ubuntu.

Releases

• bootc 1.17.4: in a minor but important docs change, jmarrero points out that bootc doesn't grow the root filesystem to fill a larger disk; if your base image doesn't, add a service that does.
• Bazzite 45: the most popular bootc desktop distribution follows Fedora to 45.
• composefs-rs 0.10.0: jmarrero fixed GHSA-8j99-gv74-3j76, where a pinned composefs= digest could be satisfied by a different image through images/refs/, and made the kernel command line, not the unsigned meta.json, decide whether fs-verity is enforced. bootc picks this up in its next release (bootc#2629).

In Case You Missed It

• bootc Sealed Images Series: John Eckersberg explained the design and usage of sealed images with Secure Boot over a series of four posts in May. Parts 2, 3 and 4.