<p>I am trying to "pass" a value from the init container to a container. Since values in a configmap are shared across the namespace, I figured I can use it for this purpose. Here is my job.yaml (with faked-out info):</p>

<pre><code>apiVersion: batch/v1
kind: Job
metadata:
  name: installer-test
spec:
  template:
    spec:
      containers:
      - name: installer-test
        image: installer-test:latest
        env:
        - name: clusterId
          value: "some_cluster_id"
        - name: in_artifactoryUrl
          valueFrom:
            configMapKeyRef:
              name: test-config
              key: artifactorySnapshotUrl
      initContainers:
      - name: artifactory-snapshot
        image: busybox
        command: ['kubectl', 'create configmap test-config --from-literal=artifactorySnapshotUrl=http://artifactory.com/some/url']
      restartPolicy: Never
  backoffLimit: 0
</code></pre>

<p>This does not seem to work (EDIT: although the statements following this edit note may still be correct, this is not working because kubectl is not a recognizable command in the busybox image), and I am assuming that the pod can only read values from a configmap created BEFORE the pod is created. Has anyone else come across the difficulty of passing values between containers, and what did you do to solve this?</p>

<p>Should I deploy the configmap in another pod and wait to deploy this one until the configmap exists?</p>

<p>(I know I can write files to a volume, but I'd rather not go that route unless it's absolutely necessary, since it essentially means our docker images must be coupled to an environment where some specific files exist)</p>

<p>You can create an <code>EmptyDir</code> volume, and mount this volume onto both containers. Unlike <code>persistent volume</code>, <code>EmptyDir</code> has no portability issue.</p>

<pre><code>apiVersion: batch/v1
kind: Job
metadata:
  name: installer-test
spec:
  template:
    spec:
      containers:
      - name: installer-test
        image: installer-test:latest
        env:
        - name: clusterId
          value: "some_cluster_id"
        volumeMounts:
        - name: tmp
          mountPath: /tmp/artifact
      initContainers:
      - name: artifactory-snapshot
        image: busybox
        command: ['/bin/sh', '-c', 'cp x /tmp/artifact/x']
        volumeMounts:
        - name: tmp
          mountPath: /tmp/artifact
      restartPolicy: Never
      volumes:
      - name: tmp
        emptyDir: {}
  backoffLimit: 0
</code></pre>
