Simple docker image which can run docker containers on a schedule (cron).
To get this to work, you must bind mount the docker socket (/var/run/docker.sock)
into the container in order to launch other containers on the host.
On startup, the container will look for a crontab file in /etc/crontab and
install it if found. Then it will launch the cron daemon and execute your commands.
Run date within an alpine:3.15 container every minute:
echo "* * * * * /usr/bin/docker run --rm alpine:3.15 date" > crontab
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v "$PWD/crontab":/etc/crontab pfrybar/cron-docker
Print a local file (on the host) within an alpine:3.15 container every minute:
echo "* * * * * /usr/bin/docker run --rm -v \"$PWD/crontab\":/data/crontab alpine:3.15 cat /data/crontab" > crontab
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v "$PWD/crontab":/etc/crontab pfrybar/cron-docker
To edit the cron commands, simply make the changes to the mounted crontab file and restart the container.