Reduce metrics mechanism to just support fastdp

prog/weaver/metrics.go

@@ -91,10 +91,10 @@ var metrics []metric = []metric{
 }
 
 func fastDPMetrics(s WeaveStatus) *weave.FastDPMetrics {
-	if reporter, ok := s.Router.OverlayDiagnostics.(weave.MetricsReporter); ok {
-		if metrics := reporter.Metrics(); metrics != nil {
-			if fastdpMetrics, ok := metrics.(*weave.FastDPMetrics); ok {
-				return fastdpMetrics
+	if diagMap, ok := s.Router.OverlayDiagnostics.(map[string]interface{}); ok {
+		if diag, ok := diagMap["fastdp"]; ok {
+			if fastDPStats, ok := diag.(weave.FastDPStatus); ok {
+				return fastDPStats.Metrics().(*weave.FastDPMetrics)
 			}
 		}
 	}

router/overlay_switch.go

@@ -42,29 +42,14 @@ func (osw *OverlaySwitch) AddFeaturesTo(features map[string]string) {
 	features["Overlays"] = strings.Join(osw.overlayNames, " ")
 }
 
-type OverlaySwitchDiagnostics map[string]interface{}
-
 func (osw *OverlaySwitch) Diagnostics() interface{} {
-	diagnostics := make(OverlaySwitchDiagnostics)
+	diagnostics := make(map[string]interface{})
 	for name, overlay := range osw.overlays {
 		diagnostics[name] = overlay.Diagnostics()
 	}
 	return diagnostics
 }
 
-type MetricsReporter interface {
-	Metrics() interface{}
-}
-
-func (d OverlaySwitchDiagnostics) Metrics() interface{} {
-	for _, entry := range d {
-		if fastDPEntry, ok := entry.(MetricsReporter); ok {
-			return fastDPEntry.Metrics()
-		}
-	}
-	return nil
-}
-
 func (osw *OverlaySwitch) InvalidateRoutes() {
 	for _, overlay := range osw.overlays {
 		overlay.InvalidateRoutes()