better entrypoint, crontab in env

docker/Dockerfile

@@ -1,10 +1,13 @@
 FROM alpine:3.16
 
 COPY logrotate-cron /etc/logrotate.d
+COPY entrypoint.sh /
 
 RUN \
   mkdir /scripts /crontabs && \
   apk -U add python3 py3-pip py3-requests py3-dateutil py3-beautifulsoup4 logrotate && \
   pip3 install fdb mysql-connector-python==8.0.29 telepot caldav
 
-ENTRYPOINT ["/usr/sbin/crond", "-f", "-d8", "-L", "/var/log/cron.log", "-c", "/crontabs"]
+ENV CRONTAB=""
+
+ENTRYPOINT ["/bin/sh", "/entrypoint.sh"]

docker/entrypoint.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+echo "${CRONTAB}" > /crontabs/root
+
+/usr/sbin/crond -f -d8 -L /var/log/cron.log -c /crontabs