Cron operator for Kubernetes

Manages multiple CronJobs with same image, but different commands and workdirs. Supports mounting of persistent volume to save results somewhere, ENV variables configmaps, concurrency and restart policy.

Build sources

You definitly need a Golang installed (easy install for Ubuntu)
Clone repository https://git.blindage.org/21h/cron-operator.git to your computer
Open Makefile and change images registry to yours, then run make && make push
Or run docker build -t cron-operator . to make image and push to your repo later
Upload image to your registry

Prebuilt images

You can find images here https://hub.docker.com/r/iam21h/cron-operator. Pin version number in operator.yaml if you do not want automaticaly get new features and bugs.

Deploy operator

Edit files and run:

kubectl -f deploy/crds/blindage_v1alpha1_cronop_crd.yaml
kubectl -f deploy/clusterrole.yaml
kubectl -f deploy/clusterrole_binding.yaml # edit service account namespace here
kubectl -n operators -f deploy/service_account.yaml
kubectl -n operators -f deploy/operator.yaml

or use Helm:

helm repo add 21h https://charts.blindage.org
helm repo update
helm install cron-operator 21h/cron-operator -n operators

Change operator.yaml if you want operator watch only specified namespace. Check deploy directory, may be you want to use Role instead of ClusterRole.

Settings

In your CronOp resource you can set image, parameters and tasks. CronJobs is a result of reconciling tasks section, some parameters can be global and overrided in each task. Remember, CronJob, Pod and Job is a different things.

Look into pkg/apis/blindage/v1alpha1/cronop_types.go for your CustomResource syntax and comments.

This parameters can be set in global section or each task:

Set Configmap with ENV variables
envConfigmap: default empty | string
Mount configmap as files
mountConfigmap: default empty | string
mountConfigmapPath: by default mounts to /configmap-local | string
Mount secret as files
mountSecret: default empty | string
mountSecretPath: by default mounts to /secret-local | string
mountSecretPermissions: default permissions, use decimal notation, default 256 | integer
How to restart Pod
restartPolicy: OnFailure | Never | Always
Limit Job restarts
backoffLimit: 0 | integer
Allow Cronjob to run concurrent Jobs
concurrencyPolicy: Allow | Forbid | Replace
Set standard kubernetes Pod security context podSecurityContext: default empty

Global history limits:

successfulJobsHistoryLimit: 3 | integer
failedJobsHistoryLimit: 3 | integer

Also you can save intermediate results in mounted persistent volume. You can set PVC name with PersistentVolumeName, mount point with PersistentVolumePath and PersistentVolumeSubPath. It's easy.

Global affinity, node selection and tolerations, have standard kubernetes specs:

nodeSelector: default empty
affinity: default empty
tolerations: default empty

Global resource limiting also kubernetes standard, but separated:

podRequests: default empty
podLimits: default empty

Labels and annotations:

Operator automatically copies labels from CR meta to Cronjob, Job and Pod.

Also you cat set annotations in CR spec to set it for Pod and merge it with individual task annotations:

---
apiVersion: blindage.org/v1alpha1
kind: CronOp
metadata:
  name: mycron
  labels:
    my-application: python-app
spec:
  image: "python:3"
  annotations:
    co.elastic.logs.backup/multiline.match: after
    co.elastic.logs.backup/multiline.negate: "true"
    co.elastic.logs.backup/multiline.pattern: ^\[
  tasks:
  - name: print-test
    annotations:
      logger: do-not-log
    commands: ['python','-c', 'print("testtesttest")']
    schedule: "* * * * *"

Your first CronOp deployment

Good sample you can find in deploy/test-cron.yaml, see it in case of questions.

This resource can help you run your first tasks:

---
apiVersion: blindage.org/v1alpha1
kind: CronOp
metadata:
  name: mycron
  labels:
    app: python
    service: testing-cron
spec:
  image: "python:3"
  tasks:
  - name: print-test
    commands: ['python','-c', 'print("doing nothing")']
    schedule: "* * * * *"
  - name: hello
    commands: ['python','-c', 'print("hello world hourly")']
    schedule: "0 * * * *"

If you delete this resource operator will delete CronJobs and Jobs.

Copyright by Vladimir Smagin (21h) 2019
http://blindage.org email: 21h@blindage.org
Project page: https://git.blindage.org/21h/cron-operator

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