firecracker-containerd VS kata-containers

My team is working on multi-cloud AWS Bottlerocket remix (Azure, GCP) with opt-in support for [firecracker-containerd](https://github.com/firecracker-microvm/firecracker-containerd) for our in-house CNCF distro, investigating microkernels applicability (tldr; they are not production-ready). We test kubernetes compat and migration plans for over 40+ cherry-picked solutions, and facing numerous compat issues for every k8s update. We do have support for Container Managed Control Planes described above, as well.

You could use a container sandbox like gVisor, light virtual machines as containers (Kata containers, firecracker + containerd) or full virtual machines (virtlet as a CRI).

There is this project, which I have never used, but seems promising. https://github.com/firecracker-microvm/firecracker-container...

Exactly, it is about secure multi-tennancy. If I recall correctly firecracker doesn't replace containerd, microVMs still runs some sort of it. Anyway, you still need a base OS because container doesn't have the whole OS image. Also I think you can have multiple containers in a single Fargate task so they have to be isolated too.

How does that compare to firecracker-containerd?

https://github.com/firecracker-microvm/firecracker-container...

This repository enables the use of a container runtime, containerd, to manage Firecracker microVMs. Like traditional containers, Firecracker microVMs offer fast start-up and shut-down and minimal overhead. Unlike traditional containers, however, they can provide an additional layer of isolation via the KVM hypervisor.

https://github.com/firecracker-microvm/firecracker-container...

I bet the first thing you think that it is a bug. There is an issue on GitHub where someone thought the same. The fact is that Kata containers are different and there are Limitations. The first I noticed too, that there is no way to share process or network namespaces between Docker containers. The fact that you cannot use the process namespace or network namespace of the host is easily understandable because we have a VM and not just a host kernel isolating our processes.

> I actually wonder how much "overhead" a VM actually has. i.e. a linux kernel that doesn't do anything (say perhaps just boots to an init that mounts proc and every n seconds read in/prints out /proc/meminfo) how much memory would the kernel actually be using?

There's already some memory sharing available using DAX in Kata Containers at least: https://github.com/kata-containers/kata-containers/blob/main...

Seems like Fly.io Machines are trying reimplement Kata Containers with the Firecracker backend [0].

Kata has a guest image and guest agent to run multiple isolated containers [1].

[0] https://katacontainers.io/

[1] https://github.com/kata-containers/kata-containers/blob/main...

> Last time I looked (a few months ago), the documentation was pretty sparse or outdated.

It still is, though it works somewhat seamlessly when installing with https://github.com/kata-containers/kata-containers/blob/main...

Though only one of the hypervisors works well.

Better to use a secure VM, can even get container-like VMs with kata-containers

As I understand,Kata Containers

Kubernetes using Kata containers as a containerd backend

https://github.com/kata-containers/kata-containers/blob/main...

My home k8s cluster is now "locked down" using micro-vms (kata-containers[0]), pod level firewalling (cilium[1]), permission-limited container users, and mostly immutable environments. Given how quickly I rolled this out; the tools to enhance cluster environment security seem more accessible now than my previous research a few years ago.

I know it's not exactly a production setup, but I really do feel that it's the most secure runtime environment I've ever had accessible at home. Probably more so than my desktops, which you could argue undermines most of my effort, but I like to think I'm pretty careful.

In the beginning I was very skeptical, but being able to just build a docker/OCI image and then manage its relationships with other services with "one pane of glass" that I can commit to git is so much simpler to me than my previous workflows. My previous setup involved messing with a bunch of tools like packer, cloud-init, terraform, ansible, libvirt, whatever firewall frontend was on the OS, and occasionally sshing in for anything not covered.

[0] https://github.com/kata-containers/kata-containers