ConfigMap data (yml format) - Kubernetes - spring-boot

Question

I have an application.yml (Spring) file, which has almost 70 fields, want to move those fields to ConfigMap.
In the process of setup ConfigMap, have realized all the 70 fields has be flatened example : webservice.endpoint.transferfund
It's gonna be a painful task to convert all the 70 fields as flat, is there any alternative.
Please suggest.
Below Config is working:
apiVersion: v1
kind: ConfigMap
metadata:
name: configmapname
namespace: default
data:
webservice.endpoint.transferfund: http://www.customer-service.app/api/tf
webservice.endpoint.getbalance: http://www.customer-service.app/api/balance
webservice.endpoint.customerinfo: http://www.customer-service.app/api/customerinfo
Below config is not working, tried it as yml format.
apiVersion: v1
kind: ConfigMap
metadata:
name: configmapname
namespace: default
data:
application.yaml: |-
webservice:
endpoint:
transferfund: http://www.customer-service.app/api/tf
getbalance: http://www.customer-service.app/api/balance
customerinfo: http://www.customer-service.app/api/customerinfo
in src/main/resources/application.yml have below fields to access ConfigMap keys:
webservice:
endpoint:
transferfund: ${webservice.endpoint.transferfund}
getbalance: ${webservice.endpoint.getbalance}
customerinfo: ${webservice.endpoint.customerinfo}
Updated:
ConfigMap Description:
C:\Users\deskktop>kubectl describe configmap configmapname
Name: configmapname
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
application.yaml:
----
webservice:
endpoint:
transferfund: http://www.customer-service.app/api/tf
getbalance: http://www.customer-service.app/api/balance
customerinfo: http://www.customer-service.app/api/customerinfo
Events: <none>
Deployment script: (configMapRef name provided as configmap name as shown above)
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: configmap-sample
spec:
replicas: 1
strategy:
type: RollingUpdate
template:
metadata:
labels:
app: configmap-sample
spec:
containers:
- name: configmap-sample
image: <<image>>
ports:
- name: http-api
containerPort: 9000
envFrom:
- configMapRef:
name: configmapname
resources:
limits:
memory: 1Gi
requests:
memory: 768Mi
env:
- name: JVM_OPTS
value: "-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=1 -Xms768M"

Answer 1

A ConfigMap is a dictionary of configuration settings. It consists of key-value pairs of strings. Kubernetes then adds those values to your containers.
In your case you have to make them flat, because Kubernetes will not understand them.
You can read in the documentation about Creating ConfigMap that:
kubectl create configmap <map-name> <data-source>
where is the name you want to assign to the ConfigMap and is the directory, file, or literal value to draw the data from.
The data source corresponds to a key-value pair in the ConfigMap, where
key = the file name or the key you provided on the command line, and
value = the file contents or the literal value you provided on the command line.
You can use kubectl describe or kubectl get to retrieve information about a ConfigMap.
EDIT
You could create a ConfigMap from a file with defined key.
Define the key to use when creating a ConfigMap from a file
Syntax might look like this:
kubectl create configmap my_configmap --from-file=<my-key-name>=<path-to-file>
And the ConfigMap migh look like the following:
apiVersion: v1
kind: ConfigMap
metadata:
creationTimestamp: 2019-07-03T18:54:22Z
name: my_configmap
namespace: default
resourceVersion: "530"
selfLink: /api/v1/namespaces/default/configmaps/my_configmap
uid: 05f8da22-d671-11e5-8cd0-68f728db1985
data:
<my-key-name>: |
key=value
key=value
key=value
key=value
Also I was able to find Create Kubernetes ConfigMaps from configuration files.
Functionality
The projector can:
Take raw files and stuff them into a ConfigMap
Glob files in your config repo, and stuff ALL of them in your configmap
Extract fields from your structured data (yaml/json)
Create new structured outputs from a subset of a yaml/json source by pulling out some fields and dropping others
Translate back and forth between JSON and YAML (convert a YAML source to a JSON output, etc)
Support for extracting complex fields like objects+arrays from sources, and not just scalars!

Answer 2

You need to mount the ConfigMap as Volume. Otherwise the content would live in environment variables. The example i post here is from https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#add-configmap-data-to-a-volume
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: k8s.gcr.io/busybox
command: [ "/bin/sh", "-c", "ls /etc/config/" ]
volumeMounts:
- name: config-volume
mountPath: /etc/config
volumes:
- name: config-volume
configMap:
# Provide the name of the ConfigMap containing the files you want
# to add to the container
name: special-config
restartPolicy: Never

Answer 3

You mentioned, you're using the application.yaml in context of a Spring project. So if you don't care whether you use .yaml or .property configuration-files, you can just use property-files because configMap generation supports them. It works with the --from-env-file flag:
kubectl create configmap configmapname --from-env-file application.properties
So in your deployment-file you can directly access the keys:
...
env:
- KEYNAME
valueFrom:
configMapKeyRef:
name: configmapname
key: KeyInPropertiesFile