instruction: Create a Kubernetes configuration for configure a pod to use a configmap | kubernetes
output: ```yaml
  apiVersion: v1
  kind: Pod
  metadata:
   name: dapi-test-pod
  spec:
   containers:
   - name: test-container
   image: gcr.io/google_containers/busybox
   command: ["/bin/sh", "-c", "env"]
   env:
   - name: SPECIAL_LEVEL_KEY
   valueFrom:
   configMapKeyRef:
   name: a-config
   key: akey
   optional: true # mark the variable as optional
   restartPolicy: Never
  ```