sysbox VS distrobuilder

You are probably referring to Sysbox (https://github.com/nestybox/sysbox), which I believe will meet your requirements (systemd, inner containers, security, etc).

Btw, Sysbox is already supported in Docker-Desktop (business tier only), so you can easily do what you want with this instruction:

$ docker run -it --rm -e SYSBOX_SYSCONT_MODE=TRUE nestybox/ubuntu-focal-systemd-docker:latest bash

Disclaimer: I'm Sysbox's co-creator and currently working for Docker.

One project in this space that looked quite promising to me is sysbox[0]. I've used them once for a gitlab runner set-up similar to what is described in their blog[1].

It's currently working great and I have not had any major crashes/incidents for at least the past 8 months.

[0]: https://github.com/nestybox/sysbox

[1]: https://blog.nestybox.com/2020/10/21/gitlab-dind.html

Today, things are very different. Docker-in-Docker has a more secure and safe approach with rootless containers and freemium tools like sysbox. Tools like sysbox let you run Docker-in-Docker without the -privileged flag and optimizes specific scenarios, like running multiple nodes of a Kubernetes cluster as ordinary containers.

Right now I am going with sysbox rootless containers. https://github.com/nestybox/sysbox

We’ve been using Sysbox (https://github.com/nestybox/sysbox) for our Buildkite based CI/CD setup, allows docker-in-docker without privileged containers. Paired with careful IAM/STS design we’ve ended up with isolated job containers with their own IAM roles limited to least-privilege.

A good alternative to the VM approach is to use Kubernetes + Sysbox (a next-gen "runc", free, open-source).

But nowadays there is an option to run such software in containers securely. It's called Sysbox, and it's a new "runc" (the piece of software that creates the containers). I am one of the developers, so I am biased, but I think you'll find it helpful.

LXC

which is what docker/podman/containerd use. If you want full system emulation look into LXC/LXD.

LXD is a manager for Linux Containers (LXC), which lets me spin up a kind-of lightweight VM for any distro, instantly. I use it to run proprietary software isolated from the rest of my system (such as Steam); disposable environments for trying stuff out, and running software that doesn't jive well with Nixos.

Check this thread on linuxcontainers LXD forum. Half way down Simos points to the eventual solution:

I found this website https://linuxcontainers.org/ and I am going to test that out for server just to see how it works.

Up to now the best documentation I have come across is the official one at linuxcontainers.org.

Containers, like LXC or Docker.

After five years managing physical servers, then another four years working with VM clusters, the value of Linux Containers(LXC) and their eventual productization as Docker appealed to me.

Docker introduced container images to the technology world, making container images a standardized delivery unit. In fact, before Docker, containerization technology already existed. Let's talk about a more recent technology, LXC (Linux Containers) in 2008. Compared to Docker, LXC is less popular since Docker provides container images, which can be more standardized and more convenient to migrate. Also, Docker created the DockerHub public service, which has become the world's largest container image repository. In addition, containerization technology can also achieve a certain degree of resource isolation, including not only CPU, memory, and other resources isolation, but also network stack isolation, which makes it easier to deploy multiple copies of applications on the same machine.