Docker in "Docker" on Fly

Hi all!

I’m curious if anyone has tried running Docker in “Docker” on Fly.io and had any success. “Docker” is in scare quotes because as I understand Fly is running OCI images in Firecracker VMs, which is why I’m curious to know if it’s somehow possible to run docker containers within my Fly application. Or podman containers.

For instance, say I wanted to run an API that allowed users to specify a container image to run, and my app would run their container and send back stdout. Or if I wanted to use Fly for a CI solution.

Would this be possible? Are there any obvious reasons why something like this would be not possible (or a silly idea)?

Patrick

At the risk of being completely off the mark… :sweat_smile:

This sounds a lot like a request for a user-friendly API over Fly-managed firecracker-containerd or kata-containers.

I hope Fly’s answer to this brings out some detail about what they’re going to migrate to, from Nomad.

I’ve been running my docker engine on fly for at least 4 months now. Docker on m1 macs sucks. GitHub - fly-apps/docker-daemon: A Docker daemon to run in Fly and access via a WireGuard peer.. This is possible because Fly.io is actually running firecracker microVMs out of your container’s rootfs.You can find more nerd content in this blog post: Docker without Docker · Fly.

TLDR: You can run almost anything that can be bundled into a docker image on Fly. And yes you have root access in your VM.

2 Likes