How to run shell script using CronJobs in Kubernetes? - kubernetes

Question

I am trying to run a shell script at regular interval of 1 minute using a CronJob.
I have created following Cron job in my openshift template:
- kind: CronJob
apiVersion: batch/v2alpha1
metadata:
name: "${APPLICATION_NAME}"
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: mycron-container
image: alpine:3
imagePullPolicy: IfNotPresent
command: [ "/bin/sh" ]
args: [ "/var/httpd-init/croyscript.sh" ]
volumeMounts:
- name: script
mountPath: "/var/httpd-init/"
volumes:
- name: script
configMap:
name: ${APPLICATION_NAME}-croyscript
restartPolicy: OnFailure
terminationGracePeriodSeconds: 0
concurrencyPolicy: Replace
The following is the configmap inserted as a volume in this job:
- kind: ConfigMap
apiVersion: v1
metadata:
name: ${APPLICATION_NAME}-croyscript
labels:
app: "${APPLICATION_NAME}"
data:
croyscript.sh: |
#!/bin/sh
if [ "${APPLICATION_PATH}" != "" ]; then
mkdir -p /var/httpd-resources/${APPLICATION_PATH}
fi
mkdir temp
cd temp
###### SOME CODE ######
This Cron job is running. as I can see the name of the job getting replaced every 1 min (as scheduled in my job). But it is not executing the shell script croyscript.sh
Am I doing anything wrong here? (Maybe I have inserted the configmap in a wrong way, so Job is not able to access the shell script)

Answer 1

Try below approach
Update permissions on configmap location
volumes:
- name: script
configMap:
name: ${APPLICATION_NAME}-croyscript
defaultMode: 0777
If this one doesnt work, most likely the script in mounted volume might have been with READONLY permissions.
use initContainer to copy the script to different location and set appropriate permissions and use that location in command parameter