title: kubernetes use env variables to pull the images
body: <p>in the yaml file can we use something like below to pull the image? or is there a better way?</p>
  
  <p>I want to pull an image but the may vary depending on the releases.</p>
  
  <p>configmap is like</p>
  
  <pre><code>kind: ConfigMap
  apiVersion: v1
  metadata:
    name: configmap
    namespace: rel
  data:
    # Configuration values can be set as key-value properties
    RELEASE_ID: 1.1.1
  </code></pre>
  
  <p>Pod is like </p>
  
  <pre><code>    imagePullPolicy: Always
      image: "sid_z:$(RELEASE_LEVEL)"
      env:
        - name: RELEASE_LEVEL
          valueFrom:
            configMapKeyRef:
              name: configmap
              key: RELEASE_ID
  </code></pre>
  
  <p>rightnow it gives me an error invalid reference format  Error: InvalidImageName</p>