Running cronjob in debian jessie container

General
7

My way is the following

a cron service in docker-compose.yml

cron:
    build:
        context: ./path/to/dockerfile
        dockerfile: Dockerfile-dev
    volumes_from:
        - applications
    command:
        - '* * * * * echo "Hello $(date)" >>/var/log/cron.log 2>&1'

Dockerfile

FROM debian:jessie
RUN apt-get update && apt-get install -y cron && \
    rm -r /var/lib/apt/lists/*
COPY cron-entrypoint.sh /cron-entrypoint.sh
RUN chmod +x /cron-entrypoint.sh
ENTRYPOINT ["/cron-entrypoint.sh"]

cron-entrypoint.sh

#!/bin/bash

touch /var/spool/cron/crontabs/root

if [ -n "$1" ]; then
  args=("$@")
  argn=$#

  for i in $(seq $argn)
  do
    echo "${args[$i-1]}" >> /var/spool/cron/crontabs/root
  done
fi

cp /var/spool/cron/crontabs/root /tmp/temp.txt
printenv | cat - /tmp/temp.txt | tee /var/spool/cron/crontabs/root
chmod 600 /var/spool/cron/crontabs/root

cron -f