TUN-7259: Add warning for missing ingress rules

Providing no ingress rules in the configuration file or via the CLI will now provide a warning and return 502 for all incoming HTTP requests.

ingress/origin_service.go

@@ -247,13 +247,26 @@ func (o helloWorld) MarshalJSON() ([]byte, error) {
 // Typical use-case is "user wants the catch-all rule to just respond 404".
 type statusCode struct {
 	code int
+
+	// Set only when the user has not defined any ingress rules
+	defaultResp bool
+	log         *zerolog.Logger
 }
 
 func newStatusCode(status int) statusCode {
 	return statusCode{code: status}
 }
 
+// default status code (502) that is returned for requests to cloudflared that don't have any ingress rules setup
+func newDefaultStatusCode(log *zerolog.Logger) statusCode {
+	return statusCode{code: 502, defaultResp: true, log: log}
+}
+
 func (o *statusCode) String() string {
+	// returning a different service name can help with identifying users via config that don't setup ingress rules
+	if o.defaultResp {
+		return "default_http_status:502"
+	}
 	return fmt.Sprintf("http_status:%d", o.code)
 }