Add router metrics

pkg/server/router/router.go

@@ -8,7 +8,9 @@ import (
 	"github.com/containous/alice"
 	"github.com/traefik/traefik/v2/pkg/config/runtime"
 	"github.com/traefik/traefik/v2/pkg/log"
+	"github.com/traefik/traefik/v2/pkg/metrics"
 	"github.com/traefik/traefik/v2/pkg/middlewares/accesslog"
+	metricsMiddle "github.com/traefik/traefik/v2/pkg/middlewares/metrics"
 	"github.com/traefik/traefik/v2/pkg/middlewares/recovery"
 	"github.com/traefik/traefik/v2/pkg/middlewares/tracing"
 	"github.com/traefik/traefik/v2/pkg/rules"
@@ -29,16 +31,18 @@ type serviceManager interface {
 type Manager struct {
 	routerHandlers     map[string]http.Handler
 	serviceManager     serviceManager
+	metricsRegistry    metrics.Registry
 	middlewaresBuilder middlewareBuilder
 	chainBuilder       *middleware.ChainBuilder
 	conf               *runtime.Configuration
 }
 
 // NewManager Creates a new Manager.
-func NewManager(conf *runtime.Configuration, serviceManager serviceManager, middlewaresBuilder middlewareBuilder, chainBuilder *middleware.ChainBuilder) *Manager {
+func NewManager(conf *runtime.Configuration, serviceManager serviceManager, middlewaresBuilder middlewareBuilder, chainBuilder *middleware.ChainBuilder, metricsRegistry metrics.Registry) *Manager {
 	return &Manager{
 		routerHandlers:     make(map[string]http.Handler),
 		serviceManager:     serviceManager,
+		metricsRegistry:    metricsRegistry,
 		middlewaresBuilder: middlewaresBuilder,
 		chainBuilder:       chainBuilder,
 		conf:               conf,
@@ -177,7 +181,13 @@ func (m *Manager) buildHTTPHandler(ctx context.Context, router *runtime.RouterIn
 		return tracing.NewForwarder(ctx, routerName, router.Service, next), nil
 	}
 
-	return alice.New().Extend(*mHandler).Append(tHandler).Then(sHandler)
+	chain := alice.New()
+
+	if m.metricsRegistry != nil && m.metricsRegistry.IsRouterEnabled() {
+		chain = chain.Append(metricsMiddle.WrapRouterHandler(ctx, m.metricsRegistry, routerName, router.Service))
+	}
+
+	return chain.Extend(*mHandler).Append(tHandler).Then(sHandler)
 }
 
 // BuildDefaultHTTPRouter creates a default HTTP router.