Fix cron (again)

Dockerfile

@@ -29,19 +29,31 @@ RUN apt-get update \
 #  && echo "apc.enable=1" >> /usr/local/etc/php/glenux-apcu.ini \
 #  && docker-php-ext-enable apcu
 
-## DO NOT install cron since it is included by default now 
-## ref: https://github.com/nextcloud/docker/blob/master/21.0/apache/Dockerfile
-# RUN apt-get install -q -y cron \
-#  && apt-get clean \
-#  && echo "*/5 * * * *  root    su -l www-data -s /bin/bash -c 'php -d memory_limit=1024M -f /var/www/html/cron.php' > /dev/null 2>&1" >> /etc/crontab
-
-# Raise memory limit for PHP
-RUN echo "memory_limit=1024M" > /usr/local/etc/php/conf.d/memory-limit.ini
-
-# CMD cron && apache2-foreground
-
 # Mandatory for bookmark extension
 # but missing from deb packages
 # RUN apt-get update \
 # && apt-get install -y php7.3-gmp
 
+
+##
+## Raise memory limit for PHP
+##
+ENV PHP_MEMORY_LIMIT=1024M
+RUN echo "memory_limit=1024M" > /usr/local/etc/php/conf.d/memory-limit.ini
+
+##
+## CRON SETUP
+##
+## Based on https://github.com/nextcloud/docker/tree/master/.examples/dockerfiles/cron/apache
+
+RUN apt-get update && apt-get install -y \
+    supervisor \
+  && rm -rf /var/lib/apt/lists/* \
+  && mkdir /var/log/supervisord /var/run/supervisord
+
+COPY supervisord.conf /etc/supervisord.conf
+
+ENV NEXTCLOUD_UPDATE=1
+
+CMD ["/usr/bin/supervisord", "-c", "/etc/supervisord.conf"]
+