[easton]

> We created a CLI that creates a rootfs from a Docker image. It pulls the image, creates a container and then extracts the fs from it to an ext4 disk.

You guys don't happen to have a public writeup about how this works, do you? Maybe it's as simple as it sounds, but Fly and CodeSandbox both have some magic to turn Docker images into VM disks that I'd like to know how to build :)

[electroly]

Fly is doing fancy stuff to avoid using docker entirely, but with docker you can just run "docker export" to dump an image to a .tar file that contains the whole filesystem. Built-in feature. I use this as a convenient way to grab a foreign platform sysroot for clang cross-compilation; just pick a Docker image and rip the filesystem out.

[phmx]

There's been a writeup on this topic by the Fly team -- https://fly.io/blog/docker-without-docker/