Install XPRA as root.

Dockerfile

@@ -2,18 +2,9 @@ FROM jupyter/scipy-notebook:hub-1.5.0
 
 # Install from APT repository
 USER root
-RUN apt-get update
+RUN apt-get update -y
 RUN apt-get install -y git
 
-# Install basics
-USER jovyan
-RUN pip3 install --upgrade pip
-
-# Install 'nice to have lab extensions'
-RUN pip install --upgrade jupyterlab
-RUN pip install jupyterlab-git==0.34.0
-RUN pip install jupyterlab-gitlab==3.0.0
-
 # Install XPRA
 RUN apt-get install -y gnupg2 apt-transport-https software-properties-common apt-utils mc
 RUN apt-get install -y yaru-theme-gnome-shell yaru-theme-gtk yaru-theme-icon
@@ -27,6 +18,15 @@ RUN apt-get install -y lightdm
 RUN rm -rf /usr/share/applications
 RUN mkdir /usr/share/applications
 
+# Install basics
+USER jovyan
+RUN pip3 install --upgrade pip
+
+# Install 'nice to have lab extensions'
+RUN pip install --upgrade jupyterlab
+RUN pip install jupyterlab-git==0.34.0
+RUN pip install jupyterlab-gitlab==3.0.0
+
 # Install for -> ewirtsch
 RUN pip install pandaSDMX==1.6.0
 RUN pip install plotly==5.4.0