title: How can I add software or other packages to a docker container?
body: <p>I have pulled jenkins container from docker hub like this: </p>
  
  <pre><code>docker pull jenkins
  </code></pre>
  
  <p>The container runs and I can access Jenkins UI in :</p>
  
  <pre><code>http://localhost:8080
  </code></pre>
  
  <p>My question is: </p>
  
  <p>If I want to be able to create a jenkins job that pulls from a github repo and I want to run some python tests from one of the test files of that repo, how can I install extra packages such as <code>virtualenvwrapper, pip, pytest, nose, selenium</code> etc?</p>
  
  <p>It appears that the docker container does not share any reference with local host file system. </p>
  
  <p>How can I install such packages in this running container?</p>
  
  <p>Thanks</p>