Get HTTP_REFERRER from Plug.Conn
<p>I developed a pixel tracking microservice using Elixir and Phoenix. I am trying to get the original URL where the pixel tracking is installed from <code>Plug.Conn</code>.</p>

<p>I assumed that I could try and get the Plug.Conn's <code>HTTP_REFERRER</code> header or variable or something but I must be wrong in maybe how the browser and HTTP works as I could not find anything about referrer in <code>Plug.Conn</code> in my controller.</p>

<p>Any ideas?</p>