Skip to content

Get started

Warning

Before starting, you must have a swarm-cronjob instance up and running using docker or an available binary for your platform.

When swarm-cronjob is ready, create a new stack to be scheduled like this one:

version: "3.2"

services:
  test:
    image: busybox
    command: date
    deploy:
      mode: replicated
      replicas: 0
      labels:
        - "swarm.cronjob.enable=true"
        - "swarm.cronjob.schedule=* * * * *"
        - "swarm.cronjob.skip-running=false"
      restart_policy:
        condition: none

You can include any configuration as long as you abide with the following conditions:

  • Set command to run the task command
  • Set mode to replicated (default)
  • Set replicas to 0 to avoid running task as soon as the service is deployed
  • Set restart_policy.condition to none. This is needed for a cronjob, otherwise the task will restart automatically
  • Add Docker labels to tell swarm-cronjob that your service is a cronjob

Once ready, deploy your scheduled stack on the swarm cluster:

docker stack deploy -c date.yml date

Logs

$ docker service logs swarm_cronjob_app
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:04:37 UTC INF Starting swarm-cronjob v1.2.0
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:04:37 UTC INF Add cronjob with schedule * * * * * service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:05:00 UTC INF Start job last_status=n/a service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:06:00 UTC INF Start job last_status=n/a service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:07:00 UTC INF Start job last_status=n/a service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:08:00 UTC INF Start job last_status=n/a service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:09:00 UTC INF Start job last_status=n/a service=date_test
swarm_cronjob_app.1.nvsjbhdhiagl@default    | Thu, 13 Dec 2018 20:10:00 UTC INF Start job last_status=n/a service=date_test
$ docker service logs date_test
date_test.1.o1d5mn4gjff3@default    | Thu Dec 13 20:11:01 UTC 2018
date_test.1.5askx244las2@default    | Thu Dec 13 20:09:00 UTC 2018
date_test.1.4lz5ez2waekk@default    | Thu Dec 13 20:12:00 UTC 2018
date_test.1.135qzpxd1ui3@default    | Thu Dec 13 20:13:01 UTC 2018
date_test.1.hngject056n3@default    | Thu Dec 13 20:10:00 UTC 2018

You can also use global mode services with swarm-cronjob. A typical use-case would be to remove unused data on your nodes using docker system prune command periodically.

To do so, create a new global stack:

version: "3.2"

services:
  prune-nodes:
    image: docker
    command: ["docker", "system", "prune", "-f"]
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
    deploy:
      mode: global
      labels:
        - "swarm.cronjob.enable=true"
        - "swarm.cronjob.schedule=0 */5 * * * *"
        - "swarm.cronjob.skip-running=false"
      restart_policy:
        condition: none

Same conditions have to be applied as replicated mode excepted:

  • Set mode to global
  • Remove replicas field as this is only used with replicated mode

Once ready, deploy your global cron stack on the swarm cluster:

docker stack deploy -c global.yml global
Last update: 2021-09-05 14:56:01
Created: 2020-09-21 23:07:39