title: E: Unable to locate package redis-server
body: <p>I am using Ubuntu machine (14.04.1). I have installed docker daemon (1.12.3 and go version: 1.6.3). I have written a dockerfile which will download redis DB. But it is throwing me following error:</p>
  
  <pre><code>E: Unable to locate package redis-server
  </code></pre>
  
  <p>I tried redis also when redis-server did not work. It again throws the same error.</p>
  
  <pre><code>E: Unable to locate package redis
  </code></pre>
  
  <p>Contents of Dockerfile:</p>
  
  <pre><code>FROM ubuntu:14.04
  
  RUN  apt-get update &amp;&amp; apt-get install -y redis-server
  
  EXPOSE 6379
  </code></pre>
  
  <p>I am able to run apt-get update but not able to install redis-server or redis. Docker's registry is docker hub. I am able to download redis in local (<code>sudo apt-get install -y redis-server</code>), outside docker but with docker I am not able to.</p>