volume mount empty on pod

I am trying to create a volume mount in a pod through a config map. Below are my defintion files:

configmap def:

apiVersion: v1
kind: ConfigMap
metadata:
  name: firstcm
data:
  appname: springboot
  database: inmemory
  tool: h2
  type: singlecontainer

deployment def:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: firstspring
  labels:
    app: firstspring
spec:
  replicas: 1
  selector:
    matchLabels:
      app: firstspring
  template:
    metadata:
      labels:
        app: firstspring
    spec:
      containers:
      - name: firstspring
        image: mukhou/firstspring
        volumeMounts:
          - name: firstvol
            mountPath: /etc/config/db.properties
            subPath: db.properties
      volumes:
        - name: firstvol
          configMap:
            name: firstcm

All objects are created fine and I can see the configmap with the data I had put. But the db.properties file that is created from config map is empty, has no data in it. Does anyone know what am I missing here?

drwxrwxrwx    2 root     root          4096 Jun  6 00:17 db.properties
/etc/config # more db.properties/
/etc/config #

Change your configmap to

apiVersion: v1
kind: ConfigMap
metadata:
  name: firstcm
data:
  db.properties: |
     appname: springboot
     database: inmemory
     tool: h2
     type: singlecontainer

This is required because you are mounting a specific key (db.properties) from your configmap