CronJob for running a ConfigMap - kubernetes

Question

I am trying to write a CronJob for executing a shell script within a ConfigMap for Kafka.
My intention is to reassign partitions at specific intervals of time.
However, I am facing issues with it. I am very new to it. Any help would be appreciated.
cron-job.yaml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: partition-cron
spec:
schedule: "*/10 * * * *"
startingDeadlineSeconds: 20
successfulJobsHistoryLimit: 5
jobTemplate:
spec:
completions: 2
template:
spec:
containers:
- name: partition-reassignment
image: busybox
command: ["/configmap/runtimeConfig.sh"]
volumeMounts:
- name: configmap
mountPath: /configmap
restartPolicy: Never
volumes:
- name: configmap
configMap:
name: configmap-config
configmap-config.yaml
{{- if .Values.topics -}}
{{- $zk := include "zookeeper.url" . -}}
apiVersion: v1
kind: ConfigMap
metadata:
labels:
app: {{ template "kafka.fullname" . }}
chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"
heritage: "{{ .Release.Service }}"
release: "{{ .Release.Name }}"
name: {{ template "kafka.fullname" . }}-config
data:
runtimeConfig.sh: |
#!/bin/bash
set -e
cd /usr/bin
until kafka-configs --zookeeper {{ $zk }} --entity-type topics --describe || (( count++ >= 6 ))
do
echo "Waiting for Zookeeper..."
sleep 20
done
until nc -z {{ template "kafka.fullname" . }} 9092 || (( retries++ >= 6 ))
do
echo "Waiting for Kafka..."
sleep 20
done
echo "Applying runtime configuration using {{ .Values.image }}:{{ .Values.imageTag }}"
{{- range $n, $topic := .Values.topics }}
{{- if and $topic.partitions $topic.replicationFactor $topic.reassignPartitions }}
cat << EOF > {{ $topic.name }}-increase-replication-factor.json
{"version":1, "partitions":[
{{- $partitions := (int $topic.partitions) }}
{{- $replicas := (int $topic.replicationFactor) }}
{{- range $i := until $partitions }}
{"topic":"{{ $topic.name }}","partition":{{ $i }},"replicas":[{{- range $j := until $replicas }}{{ $j }}{{- if ne $j (sub $replicas 1) }},{{- end }}{{- end }}]}{{- if ne $i (sub $partitions 1) }},{{- end }}
{{- end }}
]}
EOF
kafka-reassign-partitions --zookeeper {{ $zk }} --reassignment-json-file {{ $topic.name }}-increase-replication-factor.json --execute
kafka-reassign-partitions --zookeeper {{ $zk }} --reassignment-json-file {{ $topic.name }}-increase-replication-factor.json --verify
{{- end }}
{{- end -}}
My intention is to run the runtimeConfig.sh script as a cron job at regular intervals for partition reassignment in Kafka.
I am not sure if my approach is correct.
Also, I have randomly put image: busybox in the cron-job.yaml file. I am not sure about what should I be putting in there.
Information Part
$ kubectl get cronjobs
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
partition-cron */10 * * * * False 1 5m 12m
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
elegant-hedgehog-metrics-server-58995fcf8b-2vzg6 1/1 Running 0 5d
my-kafka-0 1/1 Running 1 12m
my-kafka-1 1/1 Running 0 10m
my-kafka-2 1/1 Running 0 9m
my-kafka-config-644f815a-pbpl8 0/1 Completed 0 12m
my-kafka-zookeeper-0 1/1 Running 0 12m
partition-cron-1548672000-w728w 0/1 ContainerCreating 0 5m
$ kubectl logs partition-cron-1548672000-w728w
Error from server (BadRequest): container "partition-reassignment" in pod "partition-cron-1548672000-w728w" is waiting to start: ContainerCreating
Modified Cron Job YAML
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: partition-cron
spec:
schedule: "*/5 * * * *"
startingDeadlineSeconds: 20
successfulJobsHistoryLimit: 5
jobTemplate:
spec:
completions: 1
template:
spec:
containers:
- name: partition-reassignment
image: busybox
command: ["/configmap/runtimeConfig.sh"]
volumeMounts:
- name: configmap
mountPath: /configmap
restartPolicy: Never
volumes:
- name: configmap
configMap:
name: {{ template "kafka.fullname" . }}-config
Now, I am getting Status of Cron Job pods as ContainerCannotRun.

Answer 1

You've set the ConfigMap to name: {{ template "kafka.fullname" . }}-config but in the job you are mounting configmap-config. Unless you installed the Helm chart using configmap as the name of the release, that Job will never start.
One way to fix it would be to define the volume as:
volumes:
- name: configmap
configMap:
name: {{ template "kafka.fullname" . }}-config