title: Getting information to a Plug router from the Cowboy startup call
body: <p>I'm looking for some way to get a string from my Cowboy startup call...</p>
  
  <pre><code>token = RandomString.generate()
  Plug.Adapters.Cowboy.http MyRouter, []
  </code></pre>
  
  <p>To the code used in the router:</p>
  
  <pre><code>get "/webhook/:token" do
    if token == [what I generated earlier] do
      # handle request
    end
  end
  </code></pre>
  
  <hr>
  
  <p>To be more specific: I'm working on a webhook server. I want to:</p>
  
  <ol>
  <li>Generate a secret token on server startup;</li>
  <li>Send that token to an API server which will use it for future requests to my server;</li>
  <li><em>The bit I'm struggling with:</em> Have the server compare the token supplied in requests to the generated token, and ensure a match to allow the request.</li>
  </ol>
  
  <p>I can't see anything in either of the options arguments to <code>Plug.Adapters.Cowboy.http</code> that would allow me to get user data to the router.</p>
  
  <p>How can I get the token from the function that starts cowboy to the router, so I can enforce the authentication?</p>