bubblewrap VS ostree

Nothing nix specific but you may be interested in https://github.com/containers/bubblewrap

Recently, I came across Chainguard and wrote the article How to build Docker Images with Melange and Apko. As a fervent supporter of Kubernetes and GitLab CI, I was eager to experiment with building images using Melange in this particular setup. GitLab's shared Runners work seamlessly with Bubblewrap, eliminating the need for additional configurations. This post is intended for enthusiasts like myself, interested in hosting their own Kubernetes Runners and leveraging the Kubernetes Runner Type of Melange.

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This is basically manually invoking what Flatpak does:

https://github.com/containers/bubblewrap

This is also useful for more than just security. E.G., you can test how your app would behave on a fresh install by masking your user configuration files. I personally also have a tool that uses it to basically bundle all dependencies from an entire Linux distribution in order to make highly portable AppImages— Been meaning to post that, will get around to it eventually maybe.

The flags above should hide your user data (`--tmpfs`), disable network access (`--unshare-all`), hide/virtualize devices and OS state (`--dev` and `--proc`), and make the rest of the root filesystem read-only (`--ro-bind`­— Including the insecure X11 socket in `/tmp`, which you might want to expose for GUI apps).

Check them against `bwrap --help`; I might have omitted one or two more things you'd need.

While trying to find out more comparison information, found this light on details issue:

https://github.com/containers/bubblewrap/issues/81

It mentions nsjail and minijail.

Ansible makes mutable changes to the OS, task by task.

Nix is immutable. A new change is made entirely new, and only after the build is successful, all packages are "symlinked" to the current system.

Fedora Silverblue is based on ostree [1]. It works similarly like git, but on your root tree. But it requires you to reboot the whole system for the changes to take effect. Since Nix is just symlinked packages, you don't need to reboot the system.

More detailed explanation here [2].

[1]: https://github.com/ostreedev/ostree

[2]: https://dataswamp.org/~solene/2023-07-12-intro-to-immutable-...

This one is for the ostree bug currently ongoing: https://github.com/ostreedev/ostree/issues/2900

This sounds related to the ostree bug.

I definitely agree that immutability offers considerable value in regards to improving security. But arguably it's insufficient to pull the win over mutable Fedora due to the losses caused by the inability to install the kernel-hardened package and the lack of UKI (Unified Kernel Image) support.

Other hardening guides mention a Unified Kernel Image as another measure to further improve security. Unfortunately, once more, this is (currently) not supported on Fedora Silverblue. I haven't seen it being done on openSUSE Aeon either. Though, once again, I'd love to be corrected!

The fedora crew is working on it through ostree though, so both fedora Silverblue and flatpak will be getting it (as well as true immutability) in the future: https://github.com/ostreedev/ostree/issues/2867

Aside from what has already been mentioned, Unified Kernel Image isn't supported (yet).