bootc - A new project for bootable containers

Colin Walters

March 23, 2023


  • Colin Walters, Red Hat, Inc. - Fedora/OpenShift/RHEL/CoreOS engineer
  • Why: Computing essential to society, FOSS essential to control computing


  • Transactional background OS upgrades to keep computers up to date
  • Separating applications into containers helps upgrades (of host, but also apps)

Previously at (virtual 2022)

  • Presented and demoed work on bootable containers that can be transactionally updated
  • At the time it was classified as experimental

So what changed in the last ~year?


  • The name “rpm-ostree” is very literal and suddenly becomes misleading when we’re talking about containers
  • While “ostree native container” makes sense…actually it’s also a toplevel goal to “hide” ostree

Hmmm…this is a big change in direction

  • All the work to handle “client side” customization in rpm-ostree (package layering) is no longer a focus (but it will continue to work)
  • It just makes sense to align with containers more and more at a technical and branding level

Introducing bootc!

How do I use it?

Less is more!

  • No dependency on rpm
  • ostree is a hidden implementation detail; if you have to understand it we have failed

No operating system left behind

  • Seamless in-place switch from existing ostree systems!

bootc install: Actually there is more

  • bootc started out around 500 LoC; most heavy lifting is in ostree-rust and skopeo
  • Solving “how do I use it”: podman run --privileged ... bootc install /dev/nvme0n1
  • (Though, now there’s ~3200 LoC)

bootc install: How it works

  • Creates ESP, installs grub, etc. Only handles simple cases!
  • Opinionated install of root filesystem; can boot into target OS and dynamically create other partitions
  • There’s something neat going on here: Your custom OS container image comes with a free installer!
  • Demo time

Also bootc install-to-filesystem

  • RAID, Stratis, dm-multipath: Use a separate installer
  • We’re not going to ship a GUI obviously; but those can use this as a backend
  • Both of these things are (vaguely) planned for e.g. Anaconda

What’s next

Belated status

  • This project is mainly just me, in my 12.7% time
  • I use it to update my desktop, but…probably not “production ready” yet
  • The CLI may change! (Though unlikely)

What will the next year bring?

  • I think current trajectory may be able to stabilize by EOY?
  • Obviously, hoping to gather other interested people (and OS/distros) to contribute!