如何在 docker 中执行 crontab

# PATH非常重要，因为cron bash和系统环境变量不一致
PATH="/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
 * * * * * echo hello > /proc/1/fd/1 2>/proc/1/fd/2
# An empty line is required at the end of this file for a valid cron file.

FROM ubuntu:latest
MAINTAINER docker@ekito.fr

RUN apt-get update && apt-get -y install cron

# Copy hello-cron file to the cron.d directory
COPY hello-cron /etc/cron.d/hello-cron

# Give execution rights on the cron job
RUN chmod 0644 /etc/cron.d/hello-cron

# Apply cron job
RUN crontab /etc/cron.d/hello-cron

# Create the log file to be able to run tail
RUN touch /var/log/cron.log

# Run the command on container startup
CMD ["cron", "-f"]

sudo docker build --rm -t ekito/cron-example .
sudo docker run -t -i ekito/cron-example

Hello world
Hello world