Is there any way to use configMaps in K8s with nested values to be used as environment variable in the pod? - kubernetes

Question

I have the sample cm.yml for configMap with nested json like data.
kind: ConfigMap
metadata:
name: sample-cm
data:
spring: |-
rabbitmq: |-
host: "sample.com"
datasource: |-
url: "jdbc:postgresql:sampleDb"
I have to set environment variables, spring-rabbitmq-host=sample.com and spring-datasource-url= jdbc:postgresql:sampleDb in the following pod.
kind: Pod
metadata:
name: pod-sample
spec:
containers:
- name: test-container
image: gcr.io/google_containers/busybox
command: [ "/bin/sh", "-c", "env" ]
env:
- name: sping-rabbitmq-host
valueFrom:
configMapKeyRef:
name: sample-cm
key: <what should i specify here?>
- name: spring-datasource-url
valueFrom:
configMapKeyRef:
name: sample-cm
key: <what should i specify here?>

Answer 1

Unfortunately it won't be possible to pass values from the configmap you created as separate environment variables because it is read as a single string.
You can check it using kubectl describe cm sample-cm
Name: sample-cm
Namespace: default
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","data":{"spring":"rabbitmq: |-\n host: \"sample.com\"\ndatasource: |-\n url: \"jdbc:postgresql:sampleDb\""},"kind":"Con...
Data
====
spring:
----
rabbitmq: |-
host: "sample.com"
datasource: |-
url: "jdbc:postgresql:sampleDb"
Events: <none>
ConfigMap needs key-value pairs so you have to modify it to represent separate values.
Simplest approach would be:
apiVersion: v1
kind: ConfigMap
metadata:
name: sample-cm
data:
host: "sample.com"
url: "jdbc:postgresql:sampleDb"
so the values will look like this:
kubectl describe cm sample-cm
Name: sample-cm
Namespace: default
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","data":{"host":"sample.com","url":"jdbc:postgresql:sampleDb"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"s...
Data
====
host:
----
sample.com
url:
----
jdbc:postgresql:sampleDb
Events: <none>
and pass it to a pod:
apiVersion: v1
kind: Pod
metadata:
name: pod
spec:
containers:
- name: test-container
image: gcr.io/google_containers/busybox
command: [ "/bin/sh", "-c", "env" ]
env:
- name: sping-rabbitmq-host
valueFrom:
configMapKeyRef:
name: sample-cm
key: host
- name: spring-datasource-url
valueFrom:
configMapKeyRef:
name: sample-cm
key: url