title: How to copy files to host-mounted directory in docker container
body: <p>I'm trying to copy configuration files to jenkins/jenkins image with host mounted directory.
  part of my Dockerfile:</p>
  
  <pre><code>FROM jenkins/jenkins
  COPY file.txt /var/jenkins_home/
  </code></pre>
  
  <p>Tried to use volume like this:</p>
  
  <pre><code>-v volume_name:/var/jenkins_home
  </code></pre>
  
  <p>in this case i do see "file.txt" in jenkins, but if i use:</p>
  
  <pre><code>-v /folder:/var/jenkins_home
  </code></pre>
  
  <p>i do not see file.txt in jenkins at all. so what am i miss here?</p>