title: CronJob: unknown field "configMapRef"
body: <p>I'm applying a <strong>Kubernetes CronJob</strong>.
  So far it works.
  Now I want to <strong>add the environment variables</strong>. (env: -name... see below)
  While tryng to apply I get the error </p>
  
  <blockquote>
    <p>unknown field "configMapRef" in io.k8s.api.core.v1.EnvVarSource</p>
  </blockquote>
  
  <p>I don't like to set all singles variables here. I prefer to link the configmap to not to double the variables. <strong>How is it possible set a link to the configmap.yaml variables in a CronJob file, how to code it?</strong></p>
  
  <p>Frank</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>apiVersion: batch/v1beta1
  kind: CronJob
  metadata:
    name: ad-sync
    creationTimestamp: 2019-02-15T09:10:20Z
    namespace: default
    selfLink: /apis/batch/v1beta1/namespaces/default/cronjobs/ad-sync
  spec:
    concurrencyPolicy: Allow
    failedJobsHistoryLimit: 1
    successfulJobsHistoryLimit: 3
    suspend: false
    schedule: "0 */1 * * *"
    jobTemplate:
      metadata:
        labels:
          job: ad-sync
      spec:
        template:
          spec:
            containers:
            - name: ad-sync
              image: foo.azurecr.io/foobar/ad-sync
              command: ["dotnet", "AdSyncService.dll"]
              args: []
              env:
                - name: AdSyncService
                  valueFrom:
                    configMapRef:
                      name: ad-sync-service-configmap
            restartPolicy: OnFailure</code></pre>
  </div>
  </div>
  </p>