Cron job scheduling inside a Docker container.

cronrun.sh

#!/bin/sh
cd /home/testing
timeout 10 python /home/testing/testcron.py >>/var/log/crontesting.log 2>&1

Dockerfile

# phusion baseimage initiates cron properly

# Use phusion/baseimage as base image. To make your builds reproducible, make
# sure you lock down to a specific version, not to `latest`!
# See https://github.com/phusion/baseimage-docker/blob/master/Changelog.md for
# a list of version numbers.
FROM phusion/baseimage:0.9.16

# Use baseimage-docker's init system.
CMD ["/sbin/my_init"]

# install Ubuntu packages and other items as needed
# using python example here
# install dependencies from Ubuntu repositories
RUN apt-get -qq update && \
    apt-get upgrade -y -o Dpkg::Options::="--force-confdef" -o DPkg::Options::="--force-confold" && \
    apt-get install -y -q \
        git \
        build-essential \
        python \
        python-yaml \
        python-dev \
        python-setuptools \
        python-pip \
    && \
    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# install python dependencies
RUN easy_install -U setuptools && \
    pip install -U pip

# add cron scripts and make executable
RUN mkdir /home/testing
ADD testcron.py /home/testing/testcron.py
ADD cronrun.sh /home/testing/cronrun.sh
RUN chmod +x /home/testing/cronrun.sh

# cron schedule
ADD mycrontab /home/testing/mycrontab
RUN crontab /home/testing/mycrontab

mycrontab

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# Jobs:
# m h  dom mon dow   command
  * *  *   *   *     /home/testing/cronrun.sh

testcron.py

#!/usr/bin/env python
import datetime
print "Cron job has run at %s" %datetime.datetime.now()