Cron jobs in docker (using node base to show we can use that image)

build_and_run.sh

docker build -f ./cron.docker --tag cronsample:local .
docker run -d cronsample:local --name cronsample_rhysc 

# Wait a bit, a minute in fact

docker container cp cronsample_rhysc:/var/log/cron.log ./cron.log
cat ./cron.log

# Should see "Hello world" printed on a new line for every minute the container has been running

cron.docker

FROM node:8.11.3-alpine
# https://mhdzaherghaibeh.name/2017/12/03/run-crontab-within-alpinelinux-docker-image/

RUN mkdir -p /etc/periodic/everymin
RUN echo '#!/bin/sh' >> /etc/periodic/everymin/hello
RUN echo 'echo "Hello world"  >> /var/log/cron.log 2>&1' >> /etc/periodic/everymin/hello
RUN chmod a+x /etc/periodic/everymin/hello

#  CRON definitions
#         ┌───────────── minute (0 - 59)
#         │ ┌───────────── hour (0 - 23)
#         │ │ ┌───────────── day of month (1 - 31)
#         │ │ │ ┌───────────── month (1 - 12)
#         │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday;
#         │ │ │ │ │                                       7 is also Sunday on some systems)
#         │ │ │ │ │
#         │ │ │ │ │
#         * * * * *  command to execute
RUN echo '* * * * * run-parts /etc/periodic/everymin' >> /etc/crontabs/root

ENTRYPOINT crond -l 2 -f