Run socat as a D-Bus proxy

archlinux.dockerfile

@@ -13,6 +13,7 @@ RUN systemctl enable xvfb@:99.service && \
     useradd -m -U -G users,adm gnomeshell && \
     mkdir -p /var/lib/systemd/linger && \
     touch /var/lib/systemd/linger/gnomeshell && \
+    systemctl --global enable dbus-socat@1234 && \
     systemd-machine-id-setup
 
 # dbus port

common/etc/dbus-1/session.d/tcp.conf → common/etc/dbus-1/session.d/anonymous.conf

@@ -1,7 +1,6 @@
 <!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
  "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
 <busconfig>
-    <listen>tcp:host=0.0.0.0,port=1234</listen>
     <listen>systemd:</listen>
     <apparmor mode="disabled"/>
     <auth>ANONYMOUS</auth>

common/etc/systemd/user/dbus-socat@.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Exposes D-Bus on TCP port %I
+After=dbus.socket
+
+[Service]
+ExecStart=/usr/bin/socat TCP-LISTEN:%i,fork UNIX-CONNECT:%t/bus
+
+[Install]
+WantedBy=default.target

debian.dockerfile

@@ -23,7 +23,8 @@ RUN systemctl enable xvfb@:99.service && \
     systemctl mask systemd-oomd low-memory-monitor rtkit-daemon udisks2 && \
     useradd -m -U -G users,adm gnomeshell && \
     mkdir -p /var/lib/systemd/linger && \
-    touch /var/lib/systemd/linger/gnomeshell
+    touch /var/lib/systemd/linger/gnomeshell && \
+    systemctl --global enable dbus-socat@1234
 
 # dbus port
 EXPOSE 1234

fedora.dockerfile

@@ -24,7 +24,8 @@ RUN systemctl enable xvfb@:99.service && \
     systemctl --global mask org.gnome.SettingsDaemon.Subscription && \
     adduser -m -U -G users,adm gnomeshell && \
     mkdir -p /var/lib/systemd/linger && \
-    touch /var/lib/systemd/linger/gnomeshell
+    touch /var/lib/systemd/linger/gnomeshell && \
+    systemctl --global enable dbus-socat@1234
 
 # dbus port
 EXPOSE 1234