title: Connect Docker-container by Unit-socket
body: <p>I try to connect Docker-container with inner-resource by Unit-socket.</p>
  
  <p>For this purpose I add to Dockerfile the following command:</p>
  
  <pre><code> RUN -v /var/run/docker.sock:/var/run/postgresql/.s.PGSQL.5432
  </code></pre>
  
  <p>But on the stage of docker build I receive: /bin/sh: illegal option - 
  ERROR: Service 'webapp' failed to build: The command '/bin/sh -c -v /var/run/docker.sock:/var/run/postgresql/.s.PGSQL.5432' returned a non-zero code: 2</p>
  
  <p>What am I doing wrong?</p>