Debian and Certbot: where does the package install the cron job?
In any Debian derivate, to list the files installed for a package you usually do dpkg -L.
So in your case:
dpkg -L python-certbot-apache
This is give you the list of all files installed, and where.
You can also request the list of files from packages.debian.org
From https://packages.debian.org/stretch/all/python-certbot-apache/filelist
/usr/lib/python2.7/dist-packages/certbot_apache-0.10.2.egg-info/PKG-INFO /usr/lib/python2.7/dist-packages/certbot_apache-0.10.2.egg-info/dependency_links.txt /usr/lib/python2.7/dist-packages/certbot_apache-0.10.2.egg-info/entry_points.txt /usr/lib/python2.7/dist-packages/certbot_apache-0.10.2.egg-info/requires.txt /usr/lib/python2.7/dist-packages/certbot_apache-0.10.2.egg-info/top_level.txt /usr/lib/python2.7/dist-packages/certbot_apache/__init__.py /usr/lib/python2.7/dist-packages/certbot_apache/augeas_configurator.py /usr/lib/python2.7/dist-packages/certbot_apache/augeas_lens/httpd.aug /usr/lib/python2.7/dist-packages/certbot_apache/centos-options-ssl-apache.conf /usr/lib/python2.7/dist-packages/certbot_apache/configurator.py /usr/lib/python2.7/dist-packages/certbot_apache/constants.py /usr/lib/python2.7/dist-packages/certbot_apache/display_ops.py /usr/lib/python2.7/dist-packages/certbot_apache/obj.py /usr/lib/python2.7/dist-packages/certbot_apache/options-ssl-apache.conf /usr/lib/python2.7/dist-packages/certbot_apache/parser.py /usr/lib/python2.7/dist-packages/certbot_apache/tls_sni_01.py /usr/share/doc/python-certbot-apache/changelog.Debian.gz /usr/share/doc/python-certbot-apache/copyright
It appears there is no cron job automatic added for the package.
You also need to install the package certbot
sudo apt-get install certbot
List of files:
/etc/cron.d/certbot
/lib/systemd/system/certbot.service
/lib/systemd/system/certbot.timer
/usr/bin/certbot
/usr/bin/letsencrypt
/usr/share/doc/certbot/README.rst.gz
/usr/share/doc/certbot/changelog.Debian.gz
/usr/share/doc/certbot/changelog.gz
/usr/share/doc/certbot/copyright
/usr/share/man/man1/certbot.1.gz
/usr/share/man/man1/letsencrypt.1.gz
So from this last package, the crontab files installed are actually /etc/cron.d/certbot for crontab and you have /lib/systemd/system/certbot.service + /lib/systemd/system/certbot.timer for systemd
Its actually using systemd.
I used systemctl list-unit-files | grep enabled to list my running services.
It's named certbot.timer