We have an image deployed in an AKS cluster for which we need to update a config entry during deployment using configmaps.

The configuration file has the following key and we are trying to replace the value of the "ChildKey" without replacing the entire file -

{
  "ParentKey": {
    "ChildKey": "123"
  }
}

The configmap looks like -

apiVersion: v1
data:
  ParentKey: |
    ChildKey: 456
kind: ConfigMap
name: cf

And in the deployment, the configmap is used like this -

apiVersion: extensions/v1beta1
kind: Deployment
spec:
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: abc
    spec:
      containers:
      - env:
        - name: ParentKey
          valueFrom:
            configMapKeyRef:
              key: ParentKey
              name: cf

The replacement is not working with the setup above. Is there a different way to declare the key names for nested structures?