Added debug information option (#6)

README.MD

@@ -106,6 +106,7 @@ Supported configurations per header
 | contains  | boolean  | If set to true (default false), the request is allowed if the rtequest header value contains the value specified in the configuration |
 | required  | boolean  | If set to false (default true), the request is allowed if the header is absent or the value is empty|
 | urldecode | boolean  | If set to true (default false), the value of the request header will be URL decoded before further processing with the plugin. This is useful when using this plugin with the [PassTLSClientCert](https://doc.traefik.io/traefik/middlewares/passtlsclientcert/) middleware that Traefik offers.
+| debug     | boolean  | If set to true (default false), the request headers, values and validation will be printed to the console|
 
 #
 ## Example 1 config

header_match.go

@@ -17,6 +17,7 @@ type SingleHeader struct {
 	Required  *bool    `json:"required,omitempty"`
 	Contains  *bool    `json:"contains,omitempty"`
 	URLDecode *bool    `json:"urldecode,omitempty"`
+	Debug     *bool    `json:"debug,omitempty"`
 }
 
 // Config the plugin configuration.
@@ -99,6 +100,10 @@ func (a *HeaderMatch) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 			headersValid = checkRequired(&reqHeaderVal, &vHeader)
 		}
 
+		if vHeader.IsDebug() {
+			fmt.Println("checkheaders (debug):\n\tHeaders valid:", headersValid, "\n\tRequest headers:", reqHeaderVal, "\n\tConfigured headers:", vHeader.Values)
+		}
+
 		if !headersValid {
 			break
 		}
@@ -156,6 +161,15 @@ func (s *SingleHeader) IsURLDecode() bool {
 	return true
 }
 
+//IsDebug checks whether a header value should print debug information in the log
+func (s *SingleHeader) IsDebug() bool {
+	if s.Debug == nil || *s.Debug == false {
+		return false
+	}
+
+	return true
+}
+
 //IsContains checks whether a header value should contain the configured value
 func (s *SingleHeader) IsContains() bool {
 	if s.Contains == nil || *s.Contains == false {