move code here from scripts/casper-bottom/61desktop_canary_tweaks

this should be done statically at image build time, not at boot.

debian/changelog

@@ -2,6 +2,9 @@ livecd-rootfs (24.04.13) UNRELEASED; urgency=medium
 
   * Drop support for building armhf+raspi images; as of noble these are
     arm64-only.
+  * live-build/ubuntu/hooks/020-ubuntu-live.chroot_early: move code here
+    from scripts/casper-bottom/61desktop_canary_tweaks that should be done
+    statically at image build time, not at boot.
 
  -- Steve Langasek <steve.langasek@ubuntu.com>  Fri, 08 Dec 2023 18:35:20 -0800
 

live-build/ubuntu/hooks/020-ubuntu-live.chroot_early

@@ -17,3 +17,37 @@ EOF
 cat <<EOF > /etc/initramfs-tools/conf.d/default-layer.conf
 LAYERFS_PATH=${PASS}.squashfs
 EOF
+
+# change settings to have an 'installer only' session by default
+printf "[org.gnome.desktop.a11y]\nalways-show-universal-access-status=true\n" \
+	>> /usr/share/glib-2.0/schemas/casper.gschema.override
+# we can't unload the dock because the shell would enter the overview on login;
+# https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1788
+printf "[org.gnome.shell.extensions.dash-to-dock:ubuntu]\ndock-fixed=false\nintellihide=false\n" \
+	>> /root/usr/share/glib-2.0/schemas/casper.gschema.override
+printf "[org.gnome.shell]\ndisabled-extensions=['ding@rastersoft.com']\n" \
+	>> /root/usr/share/glib-2.0/schemas/casper.gschema.override
+
+glib-compile-schemas /usr/share/glib-2.0/schemas/
+# start the installer on session start, restore normal session on close
+
+cat > /usr/lib/systemd/user/ubuntu-desktop-installer.service << EOF
+
+[Unit]
+Description=Ubuntu Desktop Installer
+PartOf=graphical-session.target
+After=graphical-session.target
+
+# Never run in GDM
+Conflicts=gnome-session@gnome-login.target
+
+[Service]
+Type=oneshot
+ExecStart=/snap/bin/ubuntu-desktop-installer --try-or-install
+ExecStopPost=sh -c "gsettings set org.gnome.shell.extensions.dash-to-dock dock-fixed true; gsettings set org.gnome.shell.extensions.dash-to-dock intellihide true; gnome-extensions enable ding@rastersoft.com"
+Restart=no
+EOF
+
+mkdir /etc/systemd/user/graphical-session.target.wants/
+ln -s /usr/lib/systemd/user/ubuntu-desktop-installer.service \
+	/etc/systemd/user/graphical-session.target.wants/