Cron in a container, based on Alpine Linux and go-crond.

This image is publicly available from:

• Quay.io: quay.io/panubo/cron
• AWS ECR Public: public.ecr.aws/panubo/cron

• Unprivileged Cron: Cron jobs run as a non-root cron user.
• Lightweight: Based on Alpine Linux.
• Flexible Logging: go-crond logs to stdout/stderr, making it easy to integrate with container logging systems.
• Mail Support: Send cron output via email using ssmtp.
• Dynamic Reloading: Crontabs can be reloaded without restarting the container.

To run a simple cron job, you need to mount a crontab file at /crontab.

crontab file:

# Run every minute
* * * * * echo "Hello from cron!"

Run the container:

docker run --rm \
  -v $(pwd)/crontab:/crontab \
  quay.io/panubo/cron

For a more persistent setup, use docker-compose:

services:
  cron:
    image: quay.io/panubo/cron:5.0.0
    container_name: my-cron-service
    restart: unless-stopped
    volumes:
      - ./crontab:/crontab
    environment:
      - TZ=Australia/Sydney
      - EMAIL_TO=your-email@example.com
      # SMTP settings if you want email notifications
      # - SMTP_HOST=smtp.example.com
      # - SMTP_PORT=587
      # - SMTP_USER=user
      # - SMTP_PASS=password
      # - EMAIL_FROM=cron@example.com

If you update the /crontab file, you can reload it without restarting the container by executing the /reload.sh script:

docker exec my-cron-service /reload.sh

Configuration is managed through environment variables.

To build the image locally, you can use the provided Makefile:

make build

• v1.x: Debian-based, using standard vixie-cron.
• v2.x: Migrated to Alpine Linux with go-crond for better container integration. Also includes additional tooling like logrotate and ssmtp.

Production ready.