GNOME extension

The GNOME extension, referred to internally as gnome, helps build snaps that use GTK 3, GNOME 42 and higher, and GLib. This extension provides many of the components needed for general desktop apps, making it useful for a broader set of apps outside of those tailored for the GNOME desktop.

This extension is compatible with the core22 and core24 bases.

Included plugs

When this extension is used, the following plugs are connected for the app. The paths slightly differ between core24 and core22 bases.

Included snap-wide plugs
snapcraft.yaml
plugs:
  desktop:
      mount-host-font-cache: false
  gtk-3-themes:
      interface: content
      target: $SNAP/data-dir/themes
      default-provider: gtk-common-themes
  icon-themes:
      interface: content
      target: $SNAP/data-dir/icons
      default-provider: gtk-common-themes
  sound-themes:
      interface: content
      target: $SNAP/data-dir/sounds
      default-provider: gtk-common-themes
  gnome-46-2404:
      interface: content
      target: $SNAP/gnome-platform
      default-provider: gnome-46-2404
  gpu-2404:
      interface: content
      target: $SNAP/gpu-2404
      default-provider: mesa-2404

The extension also connects the following plugs to all apps that use it.

Included app plugs
snapcraft.yaml
plugs:
  - desktop
  - desktop-legacy
  - gsettings
  - opengl
  - wayland
  - x11
  - mount-observe
  - calendar-service

Included packages

The GNOME extension is derived from two separate snaps – a build snap and a platform snap.

The build snap compiles libraries from source that are commonly used across GNOME apps. Examples include GLib, GTK, and gnome-desktop. These are built to provide newer versions of these packages that exist in either the core24 or core22 base snaps (a subset of their respective Ubuntu archives).

The platform snap takes the build snap and makes all of those libraries available at build time to snaps using this extension. This way, snap authors don’t need to include the pieces of the build snap that are unnecessary at runtime, like compilers, in the final snap.

Included environment variables

In addition to using the build and platform snaps, this extension sets several environment variables, links, and default plugs for the app to use, and a default build-environment for each part in your snap to use.

Build variables

The following build environment variables are added to each part in a snap that uses this extension.

You can declare additional variables in the build-environment key. Furthermore, these default variables can be overridden by declaring them in the project file.

The paths differ slightly between core24 and core22 bases.

Included build environment variables
snapcraft.yaml
build-environment:
  - PATH: /snap/gnome-46-2404-sdk/current/usr/bin${PATH:+:$PATH}
  - XDG_DATA_DIRS: $CRAFT_STAGE/usr/share:/snap/gnome-46-2404-sdk/current/usr/share:/usr/share${XDG_DATA_DIRS:+:$XDG_DATA_DIRS}
  - LD_LIBRARY_PATH: /snap/gnome-46-2404-sdk/current/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib:/snap/gnome-46-2404-sdk/current/usr/lib/vala-current:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pulseaudio${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
  - PKG_CONFIG_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/lib/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/share/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}
  - GETTEXTDATADIRS: /snap/gnome-46-2404-sdk/current/usr/share/gettext-current${GETTEXTDATADIRS:+:$GETTEXTDATADIRS}
  - GDK_PIXBUF_MODULE_FILE: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gdk-pixbuf-current/loaders.cache
  - ACLOCAL_PATH: /snap/gnome-46-2404-sdk/current/usr/share/aclocal${ACLOCAL_PATH:+:$ACLOCAL_PATH}
  - PYTHONPATH: /snap/gnome-46-2404-sdk/current/usr/lib/python3.10:/snap/gnome-46-2404-sdk/current/usr/lib/python3/dist-packages:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gobject-introspection${PYTHONPATH:+:$PYTHONPATH}
  - GI_TYPELIB_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/girepository-1.0:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/girepository-1.0${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}

Runtime variables

The following environment variables are exported when the app runs:

Environment variables
snapcraft.yaml
environment:
  SNAP_DESKTOP_RUNTIME: $SNAP/gnome-platform
  GTK_USE_PORTAL: '1'

Included layouts

This extension uses layouts to access files on the host. The platform snap’s GNOME JavaScript (GJS), webkit2gtk-4.0, and iso-codes are used so they don’t need to be packaged as part of the snap and would greatly inflate the size.

Included layouts
snapcraft.yaml
layout:
  /usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.0:
    bind: $SNAP/gnome-platform/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.0
  /usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.1:
    bind: $SNAP/gnome-platform/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.1
  /usr/share/xml/iso-codes:
    bind: $SNAP/gnome-platform/usr/share/xml/iso-codes
  /usr/share/libdrm:
    bind: $SNAP/gpu-2404/libdrm
  /usr/share/drirc.d:
    symlink: $SNAP/gpu-2404/drirc.d
  /usr/share/X11/XErrorDB:
    symlink: $SNAP/gpu-2404/X11/XErrorDB

Example expanded project file

Here’s an example of the result of Snapcraft expanding a core24-based project file, as immediately prior to build. It demonstrates the added plugs, packages, variables, and layouts that the GNOME extension includes in a project.

The original files were for the GNOME System Monitor snap. These texts contain the difference between the original file and the output of the snapcraft expand-extensions command. Some of the text has been altered for ease of reading.

Expanded project file for GNOME System Monitor
 name: gnome-system-monitor
 adopt-info: gnome-system-monitor
 summary: System Monitor
 description: |
   GNOME System Monitor is a GNOME process viewer and system monitor with
   an attractive, easy-to-use interface, It has features, such as a tree
   view for process dependencies, icons for processes, the ability to hide
   processes that you don't want to see, graphical time histories of
   CPU/memory/swap usage, the ability to kill/renice processes needing root
   access, as well as the standard features that you might expect from a
   process viewer.

 grade: stable
 confinement: strict
 base: core24

-build-snaps:
-  - gnome-46-2404/latest/candidate

 parts:
   gnome-system-monitor:
     source: https://gitlab.gnome.org/GNOME/gnome-system-monitor.git
     source-type: git
     source-tag: "46.0"
     source-depth: 1
     plugin: meson
-    parse-info: [usr/share/metainfo/gnome-system-monitor.appdata.xml]
     meson-parameters:
       - --prefix=/snap/gnome-system-monitor/current/usr
       - --buildtype=release
       - -Dsystemd=true
     organize:
       snap/gnome-system-monitor/current/usr: usr
     override-pull: |
       craftctl default
       craftctl set version=$(git describe --tags --abbrev=10)
       sed -i.bak -e 's|Icon=@APP_ID@$|Icon=${SNAP}/meta/gui/org.gnome.SystemMonitor.svg|g'  ./data/org.gnome.SystemMonitor.desktop.in.in
       sed -i.bak -E -e 's|^(NotShowIn=.*)$|# \1|g' ./data/org.gnome.SystemMonitor.desktop.in.in
     override-build: |
       craftctl default
       mkdir -p $CRAFT_PART_INSTALL/meta/gui/
       cp $CRAFT_PART_BUILD/data/org.gnome.SystemMonitor.desktop $CRAFT_PART_INSTALL/meta/gui/
       cp $CRAFT_PART_SRC/data/icons/public/hicolor/scalable/apps/org.gnome.SystemMonitor.svg $CRAFT_PART_INSTALL/meta/gui/
     build-packages:
       - desktop-file-utils
       - docbook-to-man
       - libgtop2-dev
       - libsigc++-2.0-dev
       - libsystemd-dev
       - policykit-1
       - yelp-tools
     stage-packages:
       - libsigc++-2.0-0v5
     build-snaps:
       - gnome-46-2404-sdk/latest/candidate

+    build-environment:
+      - PATH: /snap/gnome-46-2404-sdk/current/usr/bin${PATH:+:$PATH}
+      - XDG_DATA_DIRS: $CRAFT_STAGE/usr/share:/snap/gnome-46-2404-sdk/current/usr/share:/usr/share${XDG_DATA_DIRS:+:$XDG_DATA_DIRS}
+      - LD_LIBRARY_PATH: /snap/gnome-46-2404-sdk/current/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib:/snap/gnome-46-2404-sdk/current/usr/lib/vala-current:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pulseaudio${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
+      - PKG_CONFIG_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/lib/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/share/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}
+      - GETTEXTDATADIRS: /snap/gnome-46-2404-sdk/current/usr/share/gettext-current${GETTEXTDATADIRS:+:$GETTEXTDATADIRS}
+      - GDK_PIXBUF_MODULE_FILE: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gdk-pixbuf-current/loaders.cache
+      - ACLOCAL_PATH: /snap/gnome-46-2404-sdk/current/usr/share/aclocal${ACLOCAL_PATH:+:$ACLOCAL_PATH}
+      - PYTHONPATH: /snap/gnome-46-2404-sdk/current/usr/lib/python3.10:/snap/gnome-46-2404-sdk/current/usr/lib/python3/dist-packages:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gobject-introspection${PYTHONPATH:+:$PYTHONPATH}
+      - GI_TYPELIB_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/girepository-1.0:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/girepository-1.0${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}
   libraries:
     after:
       - gnome-system-monitor
     plugin: nil
     stage-packages:
       - libgtop-2.0-11
     prime:
   # Find files provided by the base and platform snap and ensure they aren't
   # duplicated in this snap
       - usr/lib/*/libgtop*
       - usr/lib/*/libsigc-2.0.so.0*
+    build-environment:
+      - PATH: /snap/gnome-46-2404-sdk/current/usr/bin${PATH:+:$PATH}
+      - XDG_DATA_DIRS: $CRAFT_STAGE/usr/share:/snap/gnome-46-2404-sdk/current/usr/share:/usr/share${XDG_DATA_DIRS:+:$XDG_DATA_DIRS}
+      - LD_LIBRARY_PATH: /snap/gnome-46-2404-sdk/current/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib:/snap/gnome-46-2404-sdk/current/usr/lib/vala-current:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pulseaudio${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
+      - PKG_CONFIG_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/lib/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/share/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}
+      - GETTEXTDATADIRS: /snap/gnome-46-2404-sdk/current/usr/share/gettext-current${GETTEXTDATADIRS:+:$GETTEXTDATADIRS}
+      - GDK_PIXBUF_MODULE_FILE: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gdk-pixbuf-current/loaders.cache
+      - ACLOCAL_PATH: /snap/gnome-46-2404-sdk/current/usr/share/aclocal${ACLOCAL_PATH:+:$ACLOCAL_PATH}
+      - PYTHONPATH: /snap/gnome-46-2404-sdk/current/usr/lib/python3.10:/snap/gnome-46-2404-sdk/current/usr/lib/python3/dist-packages:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gobject-introspection${PYTHONPATH:+:$PYTHONPATH}
+      - GI_TYPELIB_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/girepository-1.0:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/girepository-1.0${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}
   cleanup:
     after:
       - libraries
     plugin: nil
     build-snaps:
       - core24
       - gnome-46-2404
     override-prime: |
       set -eux
       for snap in "core24" "gnome-46-2404"; do
         cd "/snap/$snap/current" && find . -type f,l -exec rm -f "$CRAFT_PRIME/{}" \;
       done
+    build-environment:
+      - PATH: /snap/gnome-46-2404-sdk/current/usr/bin${PATH:+:$PATH}
+      - XDG_DATA_DIRS: $CRAFT_STAGE/usr/share:/snap/gnome-46-2404-sdk/current/usr/share:/usr/share${XDG_DATA_DIRS:+:$XDG_DATA_DIRS}
+      - LD_LIBRARY_PATH: /snap/gnome-46-2404-sdk/current/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib:/snap/gnome-46-2404-sdk/current/usr/lib/vala-current:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pulseaudio${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
+      - PKG_CONFIG_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/lib/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/share/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}
+      - GETTEXTDATADIRS: /snap/gnome-46-2404-sdk/current/usr/share/gettext-current${GETTEXTDATADIRS:+:$GETTEXTDATADIRS}
+      - GDK_PIXBUF_MODULE_FILE: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gdk-pixbuf-current/loaders.cache
+      - ACLOCAL_PATH: /snap/gnome-46-2404-sdk/current/usr/share/aclocal${ACLOCAL_PATH:+:$ACLOCAL_PATH}
+      - PYTHONPATH: /snap/gnome-46-2404-sdk/current/usr/lib/python3.10:/snap/gnome-46-2404-sdk/current/usr/lib/python3/dist-packages:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gobject-introspection${PYTHONPATH:+:$PYTHONPATH}
+      - GI_TYPELIB_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/girepository-1.0:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/girepository-1.0${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}
+  snapcraft/core:
+    build-snaps:
+      - gnome-46-2404/latest/candidate
+    plugin: nil
+    build-environment:
+      - PATH: /snap/gnome-46-2404-sdk/current/usr/bin${PATH:+:$PATH}
+      - XDG_DATA_DIRS: $CRAFT_STAGE/usr/share:/snap/gnome-46-2404-sdk/current/usr/share:/usr/share${XDG_DATA_DIRS:+:$XDG_DATA_DIRS}
+      - LD_LIBRARY_PATH: /snap/gnome-46-2404-sdk/current/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR:/snap/gnome-46-2404-sdk/current/usr/lib:/snap/gnome-46-2404-sdk/current/usr/lib/vala-current:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pulseaudio${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
+      - PKG_CONFIG_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/lib/pkgconfig:/snap/gnome-46-2404-sdk/current/usr/share/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}
+      - GETTEXTDATADIRS: /snap/gnome-46-2404-sdk/current/usr/share/gettext-current${GETTEXTDATADIRS:+:$GETTEXTDATADIRS}
+      - GDK_PIXBUF_MODULE_FILE: /snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gdk-pixbuf-current/loaders.cache
+      - ACLOCAL_PATH: /snap/gnome-46-2404-sdk/current/usr/share/aclocal${ACLOCAL_PATH:+:$ACLOCAL_PATH}
+      - PYTHONPATH: /snap/gnome-46-2404-sdk/current/usr/lib/python3.10:/snap/gnome-46-2404-sdk/current/usr/lib/python3/dist-packages:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/gobject-introspection${PYTHONPATH:+:$PYTHONPATH}
+      - GI_TYPELIB_PATH: /snap/gnome-46-2404-sdk/current/usr/lib/girepository-1.0:/snap/gnome-46-2404-sdk/current/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/girepository-1.0${GI_TYPELIB_PATH:+:$GI_TYPELIB_PATH}
+  gnome/sdk:
+    source: /snap/snapcraft/13181/share/snapcraft/extensions/desktop/command-chain
+    plugin: make
+    make-parameters:
+      - GPU_WRAPPER=gpu-2404-wrapper
+
+layout:
+  /usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.0:
+    bind: $SNAP/gnome-platform/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.0
+  /usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.1:
+    bind: $SNAP/gnome-platform/usr/lib/$CRAFT_ARCH_TRIPLET_BUILD_FOR/webkit2gtk-4.1
+  /usr/share/xml/iso-codes:
+    bind: $SNAP/gnome-platform/usr/share/xml/iso-codes
+  /usr/share/libdrm:
+    bind: $SNAP/gpu-2404/libdrm
+  /usr/share/drirc.d:
+    symlink: $SNAP/gpu-2404/drirc.d
+  /usr/share/X11/XErrorDB:
+    symlink: $SNAP/gpu-2404/X11/XErrorDB
+assumes:
+  - snapd2.43
+hooks:
+  configure:
+    command-chain:
+      - snap/command-chain/hooks-configure-fonts
+    plugs:
+      - desktop

 apps:
   gnome-system-monitor:
-    extensions: [ gnome ]
     command: usr/bin/gnome-system-monitor
     desktop: usr/share/applications/org.gnome.SystemMonitor.desktop
     plugs:
+      - desktop
+      - desktop-legacy
+      - gsettings
+      - opengl
+      - wayland
+      - x11
       - unity7
       - mount-observe
       - network-observe
       - hardware-observe
       - system-observe
       - process-control
       - run-systemd-sessions
+    command-chain:
+      - snap/command-chain/gpu-2404-wrapper
+      - snap/command-chain/desktop-launch

 plugs:
   run-systemd-sessions:
     interface: system-files
     read:
       - /run/systemd/sessions
+  desktop:
+    mount-host-font-cache: false
+  gtk-3-themes:
+    interface: content
+    target: $SNAP/data-dir/themes
+    default-provider: gtk-common-themes
+  icon-themes:
+    interface: content
+    target: $SNAP/data-dir/icons
+    default-provider: gtk-common-themes
+  sound-themes:
+    interface: content
+    target: $SNAP/data-dir/sounds
+    default-provider: gtk-common-themes
+  gnome-46-2404:
+    interface: content
+    target: $SNAP/gnome-platform
+    default-provider: gnome-46-2404
+  gpu-2404:
+    interface: content
+    target: $SNAP/gpu-2404
+    default-provider: mesa-2404

 slots:
   gnome-system-monitor:
   # for GtkApplication registration
     interface: dbus
     bus: session
     name: org.gnome.SystemMonitor

+environment:
+  SNAP_DESKTOP_RUNTIME: $SNAP/gnome-platform
+  GTK_USE_PORTAL: "1"