title: Why i get error 137 when exec lifecycle hook in Kubernetes CronJob
body: <p>I have this spec for Kubernetes CronJob</p>
  
  <pre><code>---
  kind: CronJob
  apiVersion: batch/v1beta1
  metadata:
    name: do-registry-cleanup
  
  spec:
    schedule: "* * * * *"
    successfulJobsHistoryLimit: 2
    failedJobsHistoryLimit: 4
    jobTemplate:
      spec:
        template:
          spec:
            automountServiceAccountToken: false
            restartPolicy: OnFailure
            containers:
            - name: podtest2
              image: alpine
              args:
              - wget
              - http://some_real_url/test/pod/2
              imagePullPolicy: Always
              lifecycle:
                postStart:
                  exec:
                    command:
                    - "sh"
                    - "-c"
                    - "sleep 2s;"
  </code></pre>
  
  <p>When i do <code>kubectl describe pod some_pod_name</code> i get this output (truncated) </p>
  
  <pre><code>Normal   Pulling              105s  kubelet, general-rl8c  pulling image "alpine"
  Normal   Pulled               105s  kubelet, general-rl8c  Successfully pulled image "alpine"
  Normal   Created              105s  kubelet, general-rl8c  Created container
  Normal   Started              104s  kubelet, general-rl8c  Started container
  Warning  FailedPostStartHook  104s  kubelet, general-rl8c  Exec lifecycle hook ([sh -c sleep 2s;]) for Container "podtest2" in Pod "do-registry-cleanup-1566391980-dvjdn_default(9d87fe8a-c412-11e9-8744-d2e7c0045fbd)" failed - error: command 'sh -c sleep 2s;' exited with 137: , message: ""
  Normal   Killing              104s  kubelet, general-rl8c  Killing container with id docker://podtest2:FailedPostStartHook
  </code></pre>
  
  <p>As result in this example wget is request url, and i know that sleep command is executed,not broken.
  My Question is why are:</p>
  
  <ol>
  <li>why is it occured?</li>
  <li>what are side effects of this?</li>
  </ol>
  
  <hr>
  
  <p>Some additional info. If command is "cmd1; sleep; cmd2" then cmd2 not executed. So by some reason sleep cmd invoke error in container.</p>