Docker Cron - Labels

A simple docker container to schedule the starting of docker containers using cron. Cron schedules are provided in the labels of a container, allowing "jobs" to be created on simple schedules.

Getting started

Start the jaci/cron-label container, passing through the docker socket to allow the container access to the host's docker runtime.

# Shell
docker run -d -v "/var/run/docker.sock:/var/run/docker.sock" -v "/etc/localtime:/etc/localtime:ro" jaci/cron-label:latest

# Docker-compose
services:
  cron:
    image: jaci/cron-label:latest
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
      - "/etc/localtime:/etc/localtime:ro"

Scheduling containers

Containers can be scheduled by applying the cron.schedule label. These containers must be persistent (without the --rm flag), but limited in run time (one-shot, otherwise there is no point to scheduling jobs). Restart policy should not be set.

The cron.schedule label is directly applied to the crontab file. Any crontab format that is supported by alpine linux cron is supported.

# Shell
docker run -d --label "cron.schedule=0 0 * * *" my-image:latest

# Docker-compose
services:
  my-service:
    image: my-image:latest
    restart: "no"
    labels:
      - "cron.schedule=0 0 * * *"