What APIs are required along with OCP CronJob - kubernetes

Question

I have ConfigMap, ImageStream, BuildConfig, DeploymentConfig APIs that successfully deploy my app and launch the number of pods as asked. But I want to use CronJob now.
Do I replace the DeploymentConfig completely? Because the idea is to launch a new pod according to a corn expression that is passed into the CronJob API.

Answer 1

Yes, why not 🤷, you can reuse the template 📓 section of your DeploymentConfig. For example:
kind: "DeploymentConfig"
apiVersion: "v1"
metadata:
name: "frontend"
spec:
template:
metadata:
labels:
name: "frontend"
spec:
containers:
- name: "helloworld"
image: "openshift/origin-ruby-sample"
ports:
- containerPort: 8080
protocol: "TCP"
replicas: 5
triggers:
- type: "ConfigChange"
- type: "ImageChange"
imageChangeParams:
automatic: true
containerNames:
- "helloworld"
from:
kind: "ImageStreamTag"
name: "origin-ruby-sample:latest"
strategy:
type: "Rolling"
paused: false
revisionHistoryLimit: 2
minReadySeconds: 0
would just become something like this 📃🏃:
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: frontend
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
metadata:
labels:
name: "frontend"
spec:
containers:
- name: "helloworld"
image: "openshift/origin-ruby-sample"
ports:
- containerPort: 8080
protocol: "TCP"
restartPolicy: OnFailure
✌️

Answer 2

Do I replace the DeploymentConfig completely? Because the idea is to
launch a new pod according to a corn expression that is passed into
the CronJob API.
I don't think so. Basically, "DeploymentConfig" is for running "Pod", "CronJob" is for running one-off "Pod" based on "Job". So their use cases are different each other.
For example, "DeploymentConfig" have a feature which trigger based on image changes through "ImageStream", this is required the target pod should run, not one-off one. It's not available to "CronJob".
But if you just want to use "CronJob" for the pod deployment instead of "DeploymentConfig" without image triggering feature, you should also consider how to refer the "ImageStream" on the "CronJob". Because "CronJob" is a native Kubernetes resource, so "CronJob" cannot use directly "ImageStream".
Add "alpha.image.policy.openshift.io/resolve-names: '*'" annotation to "CronJob" as follows for that. Refer Using Image Streams with Kubernetes Resources for more details.
e.g.>
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: pi
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
metadata:
annotations:
alpha.image.policy.openshift.io/resolve-names: '*' <-- You need this for using ImageStream
labels:
parent: "cronjobpi"
spec:
containers:
- name: pi
image: "<ImageStream name>"
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
restartPolicy: OnFailure
But if you don't care to use ImageStream, you can deploy the same template for containers of the pod between "DeploymentConfig" and "CronJob" as Rico mentioned. I hope if help you. :)