title: Firefox in a docker container accessible from selenium in another
body: <p>I have a docker container running a rails app (let's call it container A) that needs to do some scraping with watir webdriver using firefox as backend.</p>
  
  <p>I have firefox installed in another container (container B) and I want to be able to pass in container A something like:</p>
  
  <pre><code>Selenium::WebDriver::Firefox::Binary.path= $DOCKER_RUN_CONTAINER_A
  </code></pre>
  
  <p>So, each time watir launches firefox a new instance of CONTAINER_A launches a new firefox.</p>
  
  <p>I know it's easy to make containers communicate using ports, but how about executables?
  And, by the way, does it look like a good design idea isolating firefox in a separate container?</p>