Crond for OpenShift

This repo contains Dockerfile and OpenShift templates to run Crond.

Jobs may be configured to run as Kubernetes Jobs, from within a user defined docker images.

It uses ConfigMaps for jobs configuration and definition.

This is a temporary solution until CronJobs hit production

Usage

Create the ImageStream in your project and import it:

$ oc create -f imagestream.yaml
$ oc import-image crond

Give permission to create Job objects to service account cron:

$ oc policy add-role-to-user admin -z cron

Now, let's create a cron application named cron:

## Change "myproj" and "app" for the name of the project and image you want to execute the job in
$ oc process -f template.yaml -v NAME=cron,JOB_IMAGE_NAMESPACE=myproj,JOB_IMAGE_NAME=app | oc create -f -

Valid parameters are:

• NAME: the name of the app
• CRON_SCHEDULE: Cron schedule to excute the job
• COMMAND: Command to execute
• DOCKER_REGISTRY, JOB_IMAGE_NAMESPACE, JOB_IMAGE_NAME and JOB_IMAGE_TAG: Define image to use to run the job
• JOBS_DIR: Where to mount job's ConfigMap files

It will create the following objects:

• DeploymentConfig/cron: the crond itself, plus job management scritps from dir root/
• ConfigMap/cron-config: crond configuration
• ConfigMas/cron-jobs: list of Job objects to execute

Configure

Configs for both crond and Jobs are stored in ConfigMaps

$ oc edit configmaps/cron-config
$ oc edit configmaps/cron-jobs

In order to create new jobs simply add entries to ConfigMap/cron-jobs under key data

apiVersion: v1
kind: ConfigMap
metadata:
  name: ${NAME}-jobs
data:
  myjob: |-
    # Here goes a Pod template

Then add an entry to execute your job myjob in ConfigMaps/cron-config:

# runs job `myjob` everydat at 3:05AM
5 3 * * * cron run-job myjob

After editing ConfigMaps you must re-deploy the application:

$ oc deploy cron --latest

Job cleanup

The docker image ships with clean-jobs script to delete old Job objects and it's Pods. It's highly recomended to run it periodically:

*/5  *  *  *  * cron clean-jobs