Can Kubernetes Cronjobs Reuse Environment Variables From Existing Deployment? - kubernetes

Question

I am using a Kubernetes Cronjob to run period database restores and post restore scripts which runs against the target environment which include tasks such as working with the database, redis, and file system.
The issue I am facing is that I have to re-define all the environment variables I use in my Deployment within the Cronjob (E.g., DATABASE_NAME, DATABASE_PASSWORD, REDIS_HOST etc.).
While repeating all the environment variables works, it is error prone as I have already forgotten to update the jobs which results in me having to re-run the entire process which takes 2-4 hours to run depending on what environment.
Is there a way to reference an existing Deployment and re-use the defined environment variables within my Cronjob?

Answer 1

You can use 'kind: PodPreset' object to define and inject comman env variables into multiple kuberentes objects like deployments/statefulsets/pods/replicasets etc.
Follow the link for help --> https://kubernetes.io/docs/tasks/inject-data-application/podpreset/

Answer 2

I don't think so you can reuse environment variables until it is coming from secrets or configmaps.So if you don't want to use secrets for non sensitive data then you can use configmaps as like below
kubectl create configmap redis-uname --from-literal=username=jp
[root#master ~]# kubectl get cm redis-uname -o yaml
apiVersion: v1
data:
username: jp
kind: ConfigMap
metadata:
creationTimestamp: "2019-11-28T21:38:18Z"
name: redis-uname
namespace: default
resourceVersion: "1090703"
selfLink: /api/v1/namespaces/default/configmaps/redis-uname
uid: 1a9e3cce-50b1-448b-8bae-4b2c6ccb6861
[root#master ~]#
[root#master ~]# echo -n 'K8sCluster!' | base64
SzhzQ2x1c3RlciE=
[root#master ~]# cat redis-sec.yaml
apiVersion: v1
kind: Secret
metadata:
name: redissecret
data:
password: SzhzQ2x1c3RlciE=
[root#master ~]#
[root#master ~]# kubectl apply -f redis-sec.yaml
secret/redissecret created
[root#master ~]# kubectl get secret redissecret -o yaml
apiVersion: v1
data:
password: SzhzQ2x1c3RlciE=
kind: Secret
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"v1","data":{"password":"SzhzQ2x1c3RlciE="},"kind":"Secret","metadata":{"annotations":{},"name":"redissecret","namespace":"default"}}
creationTimestamp: "2019-11-28T21:40:18Z"
name: redissecret
namespace: default
resourceVersion: "1090876"
selfLink: /api/v1/namespaces/default/secrets/redissecret
uid: 2b6acdcd-d7c6-4e50-bd0e-8c323804155b
type: Opaque
[root#master ~]#
apiVersion: v1
kind: Pod
metadata:
name: "redis-sec-env-pod"
spec:
containers:
- name: redis-sec-env-cn
image: "redis"
env:
- name: username
valueFrom:
configMapKeyRef:
name: redis-uname
key: username
- name: password
valueFrom:
secretKeyRef:
name: redissecret
key: password
[root#master ~]# kubectl apply -f reddis_sec_pod.yaml
pod/redis-sec-env-pod created
[root#master ~]# kubectl exec -it redis-sec-env-pod sh
# env|grep -i user
username=jp
# env|grep -i pass
password=K8sCluster!
#