woah that's actually awesome. I feel like adding uh storage usage limits could also be easy as well.

But the one thing that I always wonder is about (virtualization?) in the sense of something like docker just for containerizing or some sort of way of running them in some sort of sandbox without much performance issues or something, I am kinda interested in knowing what might be the best way of doing so (is podman the right way or some other way like bubblewrap?)

Edit: just discovered in the comment below the (parents parents?)comment that there is systemd isolation too, that sounds very interesting and the first time I personally heard of it hmm

You can achieve similar results with podman and bubblewrap, but podman handles things like networking, resource and image management that bubblewrap doesn't by itself

Bubblewrap really is more for sandboxing "transient" containers and being able to separate specific things from the host (such as libraries), with other applications handling the image management, which makes sense because its primary user is Flatpak and Steam. Once the application inside the container is exited, the sandbox is destroyed, it's job is done.

Podman is a Docker clone, it's for development or persistent containers. It will monitor containers, restart them, can pull image updates, setup networks between them etc.

They both use namespacing and cgroups under the hood, but for different results and purposes.

Your right that systemd has sandboxing too, and it also uses the same features as the kernel. Podman can also export it's services to be managed by systemd.

There's literally so much choice when it comes to making containers on Linux.

I'm fairly confident that systemd, docker, podman, bubblewrap, unshare, and probably other tools are all wrapping the same kernel features, so I'd expect a certain degree of convergence in what they provide.

I wrote my comment before I saw yours, but you'll probably be interested in it[0].

The best thing about systemd is also the worst thing: it's monolithic. You can containarize applications lightly all the way to having a full fledged VM. You can run as user or root. You can limit system access like CPU, RAM, network, and even the physical hardware. You even have homed which gives you more control over your user environments. There's systemd mounts[1], boot, machines, timers, networks, and more. It's overwhelming.

I think two commands everyone should know if dealing with systemd services is:

  - `systemctl edit foo.service` to create an override file which sits on top of the existing service file (so your changes don't disappear when you upgrade)
  - `systemd-analyze security foo.service` which will give you a short description of the security options and a score specifying your exposure level.

I've replaced all my cron jobs with systemd jobs now and while it is a bit more work up front (just copy paste templates...) there are huge benefits to be had. Way more flexibility in scheduling and you're not limited to such restrictions as your computer being off[3]

[0] https://news.ycombinator.com/item?id=45318649

[1] I've found mounts really helpful and can really speed up boot times. You can make your drives mount in the background and after any service you want. You can also set timeouts so that they will power down and automount as needed. That can save you a good amount on electricity if you got a storage service. This might also be a good time to remind people that you likely want to add `noatime` to your mount options (even if you use fstab)[2].

[2] https://opensource.com/article/20/6/linux-noatime

[3] You can have it run the service on the next boot (or whenever) if it was supposed to run when the machine was powered off.

Kubernetes is also this but for the cloud. CPU/Mem/Storage limits