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Wyrcan: the Container Bootloader Saga

Nathaniel McCallum

Title: Wyrcan: the Container Bootloader Saga
Author: Nathaniel McCallum
Date: July 31, 2022

Wyrcan is a bootloader that boots into a container. That's all it does.

But of course, that's not the only thing that Wyrcan implies. Using Wyrcan to boot a container also means that you can use a tried and trusted software packaging ecosystem to have a bare-metal OS that is:

  • Stateless: Booting a container with Wyrcan means that nothing is installed on the disk. There is no state to manage except the state you put into your container. You never have to worry about whether packages are updated: you can schedule reboots to make sure you always have the latest OS. And if all your mounts of local storage are noexec, you can just reboot when compromised.
  • Memory-Resident: The full operating system is resident in RAM. That means it is fast. However, you can also set up swap in your container so that unused pages are written to disk, saving memory for your application.
  • Declarative: Your bare-metal operating system is developed using the same delarative tooling that you have come to expect from the container development pipeline. But your OS config in git. Host it in your favorite git forge (GitHub, GitLab, Bitbucket, etc). Build the images automatically. Host them in your favorite container repo.

Source: SCALE 19x 2022