* had a hard time with docker image only to find out in the end - after hours - that I commented out the matrix-commander command for testing purposes :see-no-evil:

* There is still testing if I use ENTRYPOINT in the _Dockerfile_ or only entrypoint in the _docker-compose.yml_ as the latter worked well and without any problem.
* fritzab2matrix.py is now executable (WATCHOUT! The hashbang points to your system's python3 NOT to your virtualenv where the dependencies are met!)
* the monitoring is now part of the main function

docker/Dockerfile

@@ -3,23 +3,20 @@
 FROM ubuntu:latest
 
 ENV TZ=Europe/Berlin
-RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 
 WORKDIR /app
 VOLUME /app
 
 COPY . .
 
-RUN ls -la
-RUN ["cat", "/app/requirements.txt"]
-
-RUN /bin/bash -c 'apt update && apt install -y libolm-dev python3-pip ffmpeg;'
+RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone; \
+    /bin/bash -c 'apt update && apt install -y libolm-dev python3-pip ffmpeg htop; \
+    pip install update pip && pip install -r requirements.txt ;'
 
 
-RUN pip install update pip && pip install -r requirements.txt
 
-
-CMD python3 fritzab2matrix.py && tail -f /dev/null
+ENTRYPOINT ["./fritzab2matrix.py "]
+