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

Right now, bubbles is distributed via a container outputting the required binaries into $HOME/bubbles.

Requirements:

• podman/docker for installation
• passt
• qemu-img
• curl

Loose Recommendation:

• btrfs as backing filesystem (seems to optimize for disk image deduplication under the hood)

Install

mkdir $HOME/bubbles
# May be different for non-SELinux systems: skip ":Z"
# May be different for docker: You may need to chown files afterwards
podman run -v "$HOME/bubbles:/output:Z" ghcr.io/gonicus/bubbles/bubbles:841f165307e5d15b789cd8fc1aab40b7ecef6f3e
# For .desktop file:
cat > ~/.local/share/applications/bubbles.desktop <<EOF
[Desktop Entry]
Type=Application
Version=1.0
Name=Bubbles
Exec=sh -c 'cd $HOME/bubbles && LD_LIBRARY_PATH=$HOME/bubbles/runtime_libs $HOME/bubbles/bubbles'
EOF

Run

Start "Bubbles" via desktop, then:

1. Press image download button, await completion
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)

$ sudo nix-channel --update
$ nix-shell -p home-manager
$ home-manager init
$ vim /home/user/.config/home-manager/home.nix # Add packages from nixpkgs
$ home-manager switch # Ensure that /home/user/.nix-profile/bin is in PATH afterwards

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

Current limitations

TODO's in Bubbles

• Distribution via flatpak
• MS Windows support
• More choices beyond Debian+Nix as guest system: e. g. Arch Linux

Imaginable opt-in Features:

• Option to share Nix store with other VMs/Bubbles
• Option to mount host directories
• Option to enable pulseaudio socket forwarding
• Option to promote .desktop files to host

Limitations from upstream components

• EGL/GPU hardware acceleration not trivial
  • For AMD, addressable using virtio native contexts, WIP
• For some Wayland applications, sommelier crashes

Using the work in...

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