Solution to the issue 'No output using this example #1'

Dockerfile

@@ -1,12 +1,23 @@
-FROM python:3.7
+FROM python:3.10
+
 RUN apt-get update && apt-get -y install cron vim
+
 WORKDIR /app
+
 COPY crontab /etc/cron.d/crontab
 COPY hello.py /app/hello.py
+
 RUN chmod 0644 /etc/cron.d/crontab
-RUN /usr/bin/crontab /etc/cron.d/crontab
+RUN crontab /etc/cron.d/crontab
+
+# Create a virtual environment
+RUN python -m venv /opt/venv
 
-# run crond as main process of container
-CMD ["cron", "-f"]
+# Activate the virtual environment
+ENV PATH="/opt/venv/bin:$PATH"
 
+# Create empty log (TAIL needs this)
+RUN touch /tmp/out.log
 
+# Run cron and tail the log
+CMD cron && tail -f /tmp/out.log

crontab

@@ -1,3 +1,3 @@
 # START CRON JOB
-* * * * * python /app/hello.py > /proc/1/fd/1 2>/proc/1/fd/2
-# END CRON JOB
+* * * * * python3 /app/hello.py >>/tmp/out.log 2>/tmp/err.log
+# END CRON JOB