title: Can't connect to 'docker' daemon on building kubernetes from source
body: <p>I was trying to build kubernetes from source: 
  <a href="https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/getting-started-guides/binary_release.md#building-from-source" rel="nofollow">https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/getting-started-guides/binary_release.md#building-from-source</a></p>
  
  <p>I have docker installed on my ubuntu.</p>
  
  <pre><code>royalharsh95@ubuntu:~$ sudo docker version
  
  Client version: 1.0.1
  
  Client API version: 1.12
  
  Go version (client): go1.2.1
  
  Git commit (client): 990021a
  
  Server version: 1.0.1
  
  Server API version: 1.12
  
  Go version (server): go1.2.1
  
  Git commit (server): 990021a
  </code></pre>
  
  <p>I tried after <code>sudo service docker start</code> but got the same error.</p>
  
  <pre><code>royalharsh95@ubuntu:~$ cd kubernetes
  
  royalharsh95@ubuntu:~/kubernetes$ make release
  
  build/release.sh
  
  +++ Verifying Prerequisites....
  
  Can't connect to 'docker' daemon.  please fix and retry.
  
  Possible causes:
  
  - On Mac OS X, boot2docker VM isn't installed or started
  
  - On Mac OS X, docker env variable isn't set appropriately. Run:
        $(boot2docker shellinit)
  
   - On Linux, user isn't in 'docker' group.  Add and relogin.
      - Something like 'sudo usermod -a -G docker royalharsh95'
      - RHEL7 bug and workaround: https://bugzilla.redhat.com/show_bug.cgi?id=1119282#c8
    - On Linux, Docker daemon hasn't been started or has crashed
  
  make: *** [release] Error 1
  </code></pre>