code: func (wfe *WebFrontEndImpl) Index(ctx context.Context, logEvent *web.RequestEvent, response http.ResponseWriter, request *http.Request) {
  	// http://golang.org/pkg/net/http/#example_ServeMux_Handle
  	// The "/" pattern matches everything, so we need to check
  	// that we're at the root here.
  	if request.URL.Path != "/" {
  		logEvent.AddError("Resource not found")
  		http.NotFound(response, request)
  		response.Header().Set("Content-Type", "application/problem+json")
  		return
  	}
  
  	if request.Method != "GET" {
  		logEvent.AddError("Bad method")
  		response.Header().Set("Allow", "GET")
  		response.WriteHeader(http.StatusMethodNotAllowed)
  		return
  	}
  
  	addNoCacheHeader(response)
  	response.Header().Set("Content-Type", "text/html")
  	fmt.Fprintf(response, `<html>
  		<body>
  			This is an <a href="https://github.com/ietf-wg-acme/acme/">ACME</a>
  			Certificate Authority running <a href="https://github.com/letsencrypt/boulder">Boulder</a>.
  			JSON directory is available at <a href="%s">%s</a>.
  		</body>
  	</html>
  	`, directoryPath, directoryPath)
  }
docs: // Method implementations
  // Index serves a simple identification page. It is not part of the ACME spec.