Run crontab with docker image

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Problem

You have put your application in docker image, and you have cron task to run.

Solution

Put your crontab script to the image too, and run both from docker-compose.

  1. Say you have a crontab task like this: 10 * * * * python3 /app/del_tmp_file.py

  2. Put those lines to a file like doc/project.cron

  3. In Dockerfile:

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    COPY doc/project.cron /etc/cron.d/project.cron
    RUN chmod 0644 /etc/cron.d/project.cron && crontab /etc/cron.d/project.cron

    This will add your cron task to crontab

Now you already have put the crontab and application to your docker image. Edit docker-compose to start both:

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version: "3"

services:
  app:
    image: yourimage:latest
    entrypoint: ["./app.py"]
    ports:
      - "127.0.0.1:6767:6767"
    volumes:
      - ./etc:/home/app/etc
      - ./logs:/home/app/logs
      - ./public:/home/app/public
  cron:
    image: yourimage:latest
    user: root
    entrypoint: [ "cron", "-f" ]
    volumes:
      - ./etc:/home/app/etc
      - ./logs:/home/app/logs

The key is for run the crontab, make the entrypoint to be ["cron", "-f"].