Bubbles - lightweight Linux working environments

Quick: Starts up in just a few seconds

Disposable: Do not break your host; Break your bubble and discard it

Isolated: Strong KVM isolation boundary

Immutable: Includes Nix to enable version-controlled, reproducible work environments

Mutable: If Nix is too strict, fall back on Debian's apt or install any other package manager

Atomic Desktop Friendly: Works within e. g. Fedora Atomic desktops

Rootless: Does not require host root access

Integrated: Wayland windows are managed on the host compositor

Getting started

Required libraries:

• libwayland-client
• libcap
• glibc

These libraries are present on usual distributions (and NixOS via nix-ld), but their need should be removed in later releases.

Download the flatpak file for the latest app-v* release from releases.

Install it:

flatpak install --bundle $HOME/Downloads/de.gonicus.Bubbles.flatpak

Run

Start "Bubbles" via desktop, then:

1. Press image download button, await completion
   • This downloads a pre-built VM image (disk.tar.gz) published as a GitHub Release artifact, verifies its checksum, and extracts it locally.
2. Press VM creation button, enter name, confirm
3. Start VM, await startup and initial setup
4. Press Terminal button
5. Enjoy mutable Debian+Nix Installation
6. (Optional, yet recommended: Setup Nix home-manager, see "Cheat Sheet")

The installed system is a Debian Trixie with preinstalled...

• Gnome Console (kgx)
• Nix
• sommelier
• starship (configured for nerdfonts)
• bubbles-agent (simple agent for serving needs of the UI)

On first boot, it will fetch a nerdfont.

Cheat sheet

Install home-manager (recommended, it's worth it)

$ /opt/home-manager-bootstrap init
$ /opt/home-manager-bootstrap switch
# Home Manager is initialized!
$ vim ~/.config/home-manager/home.nix # Add packages from nixpkgs
$ home-manager switch

Change default terminal

• sudo update-alternatives --config x-terminal-emulator

Enforcing Wayland

• Chromium: chromium --ozone-platform=wayland
• Firefox: WAYLAND_DISPLAY=wayland-0 firefox
• VS Code:
  • mkdir -p ~/.config/Code/User && echo '{"window.titleBarStyle": "custom"}' > ~/.config/Code/User/settings.json
  • code --ozone-platform=wayland

Sound socket forwarding

1. On host: socat VSOCK-LISTEN:11112,fork UNIX-CONNECT:$XDG_RUNTIME_DIR/pulse/native
2. On guest: mkdir $XDG_RUNTIME_DIR/pulse && sudo chown user: $XDG_RUNTIME_DIR/pulse && socat UNIX-LISTEN:$XDG_RUNTIME_DIR/pulse/native,fork VSOCK-CONNECT:2:11112

Comparisons

Compared to distroboxes...

Pro Bubbles:

• allows straight-forward use of containers
• provides isolation

Contra Bubbles:

• not as host-integrated as distroboxes

Compared to devcontainers...

Pro Bubbles:

• allows straight-forward use of containers (hence also devcontainers)

Contra Bubbles:

• not part of devcontainer ecosystem

Compared to allround VM solutions like Gnome Boxes...

Pro Bubbles:

• does not require stepping through OS installers
• opinionated networking etc.
• allows Wayland integration

Contra Bubbles:

• does not support traditional VM handling use cases

Using the work in...

• crosvm + sommelier
• Relm4
• rust-gtk4
• passt
• distrobuilder
• ...