Beginning of the story
Shortly after the Questing Quokka was released, the Rockcrafters team got a new mission: to introduce the wild-type Resolute Raccoon to the Medusa, who would turn it into a firmly built, mineral-rich rock.
However, to reach out to a Greek Gorgon is not an easy job, and especially to let that Gorgon shed a proper gaze at the Resolute Raccoon, since our raccoon breed doesn’t even have a kernel (surely, as it is a container image).
Therefore, the Rockcrafters came up with a two-phase approach to petrify this very raccoon in a controlled manner.
Before the journey starts, the Rockcrafters would like to share a bit of the background knowledge on the origin of this raccoon breed.
Before the Rock — The beginning of the Resolute Raccoon
The very first trace of Resolute Raccoon was spotted (the name reveal) on 6th October, 2025, when the Ubuntu engineers were putting the last chip of the puzzle to release the Questing Quokka.
Reported by Docker Hub, the first kernel-less Resolute Raccoon was seen on the first day of November, 2025. Although the Rockcrafters would like to find such a Resolute Raccoon in a rock format, this Resolute Raccoon had nothing to do with being a rock, up until that point.
So, what makes a container image a rock? Firstly, it should be an OCI-compliant container image whose structure is defined by the OCI Specification. Secondly, a Pebble should be embedded there, sitting as the housekeeper of the services inside this rock, especially for derivative downstream builds based on this Ubuntu base rock. Finally, it should be petrified by Medusa. Well, as the Gorgon isn’t necessarily willing to spend her time with our mascots, we did obtain a handy oracle from her, which is Rockcraft.
To create a concise build recipe tailored for a petrified Resolute Raccoon, it is important to understand how the existing ones are brought to life before we start the petrifying process.
The build recipe behind the existing Resolute Raccoon
The root filesystem of the non-petrified Resolute Raccoon was built by live-build. This mighty tool builds almost all kinds of Ubuntu live systems, including server, desktop, and base container images.
When an image is built inside Canonical’s machinery, `live-build` is invoked to build the images of different types and find out what packages need to be installed on top of a minimal base image.
The packages to be installed for each Ubuntu image are determined by the seeds of Ubuntu.
livecd-rootfs, a wrapper around live build, obtains a list of the packages to be installed from a corresponding seed by calling Germinate, and installs these packages once a base system (a runnable root filesystem) is bootstrapped by live-build, which calls into debootstrap for the heavy-lifting.
debootstrap sits in the core position of the whole build process. It bootstraps the root filesystem from the void with two major phases:
- In the first phase,
debootstrapfetches all the packages marked with thePriority: requiredfrom the archive, extracts them into the target root filesystem, and sets up the required system directories (e.g.,/etc) for the second phase. At this point, the target root filesystem is already capable of beingchrooted into and running basic commands. - The second phase,
debootstrapfeigns the installation of all the packages extracted in the first phase, unpacks and configures the required packages with thechrooted invokes of thedpkginside the target root filesystem, overwrites the feigneddpkgstatus files, and finally installs the additional packages required to form the complete base system.
Keeping the oath that minimization is the core philosophy behind creating a base container image, we should limit the number of packages to be installed to the absolute minimum. Therefore, no more packages were installed for the Resolute Raccoon base container image.
Finally, the wrapping scripts and hooks from livecd-rootfs are applied to the Resolute Raccoon, further minimizing its size and giving it the enlightenments (initial configurations, e.g., archive sources and the default user) to ensure it works right out of the box.
The first step of petrifying the Resolute Raccoon
We’ve conducted a pilot work to adapt the Resolute Raccoon to be encapsulated in a rock, and accustom the future keepers of the Resolute Raccoon to spawning it as a rock.
We kept the build mechanism of its root filesystem untouched, but packed the Resolute Raccoon with Rockcraft, which served as an alternative to the Docker Buildkit in the existing build pipelines.
Following a community review, the Resolute Raccoon rock is now available on Docker Hub starting from the serial 20260312.
The Resolute Raccoon container image, fully petrified
Across different cultures, there exists a shared connection between stone and mythologies. In ancient Greece, the Gorgon Medusa has the capability of turning anyone who looks upon her to stone, while in the Chinese literature Journey to the West, the main character Sun Wukong is a monkey born from a stone under the supernatural powers acquired through Taoist practices.
In the Ubuntu culture, Rockcraft enables developers to create rocks – a new generation of secure, stable, and OCI-compliant container images, based on Ubuntu.
Since the Resolute Raccoon was successfully tamed and trapped in a rock, the Rockcrafter wondered if it was possible to have its complete lifecycle – from bootstrap to the packed artifact – all happen in the context of a rock.
To let the Resolute Raccoon become a rock completely, a decent amount of jobs were conducted, not in a quarry, but in the build recipe of the Resolute Raccoon rock — the rockcraft.yaml file.
Given that the base container images don’t need any packages other than the ones with the required priority, and the Advanced Package Tool (apt), the build process could be drastically simplified by stripping down the germination process, which was already done when putting up the archive. The logic from the live build tools handling the booting, the kernel, and the extra configurations could also be safely disregarded. This results in a compact build recipe that only depends on the debootstrap, supplemented by some scripts to post-process the base system.
The epilogue
Now, the Resolute Raccoon is successfully containerized in a rock, utilizing the latest rockcrafting technology from Canonical, unable to escape from the gaze of Merciless Medusa.
The successful petrification of the Resolute Raccoon relied on the massive power provided by Rockcraft, and the Rockcrafters wish the readers: May the force of crafting be with you.