title: NGINX ingress auth-url returning 404 but the endpoint exists
body: <p>Adding the annotation:</p>
  
  <pre><code>  annotations:
      nginx.ingress.kubernetes.io/auth-url: http://my-auth-service.my-api.svc.cluster.local:8080
  </code></pre>
  
  <p>...to my ingress rule causes a 500 response from the ingress controller (the ingress works without it).</p>
  
  <p>The service exists and I can ssh into the ingress controller and CURL it, getting a response:</p>
  
  <p><code>curl http://my-auth-service.my-api.svc.cluster.local:8080</code> Produces a 200 response.</p>
  
  <p>I checked the ingress controller logs but it says that the service returned a <code>404</code>. If I can CURL to the same URL why would it return a <code>404</code>?</p>
  
  <pre><code>2019/07/01 20:26:11 [error] 558#558: *443367 auth request unexpected status: 404 while sending to client, client: 192.168.65.3, server: localhost, request: "GET /mocks HTTP/1.1", host: "localhost"
  </code></pre>
  
  <p>I'm not sure what to check to deterine the problem.</p>