title: kubectl not able to pull the image from private repository
body: <p>I am running kubeadm alpha version to set up my kubernates cluster. 
  From kubernates , I am trying to pull docker images which is hosted in nexus repository. 
  When ever I am trying to create a pods , It is giving  "ImagePullBackOff" every time. Can anybody help me on this ?</p>
  
  <p>Detail for this are present in <a href="https://github.com/kubernetes/kubernetes/issues/41536" rel="noreferrer">https://github.com/kubernetes/kubernetes/issues/41536</a></p>
  
  <p>Pod definition : </p>
  
  <pre><code>apiVersion: v1
  kind: Pod
  metadata:
    name: test-pod
    labels:
      name: test
  spec:
    containers:
      - image: 123.456.789.0:9595/test
        name: test
        ports:
          - containerPort: 8443
    imagePullSecrets:
      - name: my-secret
  </code></pre>