Label http request handler tracing spans with the matched route name (#…

…126)

* Pass options to tracing middleware

Signed-off-by: Goutham Veeramachaneni <[email protected]>

* Use the route matcher instead

Signed-off-by: Goutham Veeramachaneni <[email protected]>

middleware/http_tracing.go

@@ -1,6 +1,7 @@
 package middleware
 
 import (
+	"fmt"
 	"net/http"
 
 	"github.com/opentracing-contrib/go-stdlib/nethttp"
@@ -10,11 +11,22 @@ import (
 )
 
 // Tracer is a middleware which traces incoming requests.
-type Tracer struct{}
+type Tracer struct {
+	RouteMatcher RouteMatcher
+}
 
 // Wrap implements Interface
 func (t Tracer) Wrap(next http.Handler) http.Handler {
-	traceHandler := nethttp.Middleware(opentracing.GlobalTracer(), next)
+	opMatcher := nethttp.OperationNameFunc(func(r *http.Request) string {
+		op := getRouteName(t.RouteMatcher, r)
+		if op == "" {
+			return "HTTP " + r.Method
+		}
+
+		return fmt.Sprintf("HTTP %s - %s", r.Method, op)
+	})
+
+	traceHandler := nethttp.Middleware(opentracing.GlobalTracer(), next, opMatcher)
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var maybeTracer http.Handler
 		// Don't try and trace websocket requests because nethttp.Middleware

middleware/instrument.go

@@ -64,16 +64,26 @@ func (i Instrument) Wrap(next http.Handler) http.Handler {
 // We do all this as we do not wish to emit high cardinality labels to
 // prometheus.
 func (i Instrument) getRouteName(r *http.Request) string {
+	route := getRouteName(i.RouteMatcher, r)
+	if route == "" {
+		route = "other"
+	}
+
+	return route
+}
+
+func getRouteName(routeMatcher RouteMatcher, r *http.Request) string {
 	var routeMatch mux.RouteMatch
-	if i.RouteMatcher != nil && i.RouteMatcher.Match(r, &routeMatch) {
+	if routeMatcher != nil && routeMatcher.Match(r, &routeMatch) {
 		if name := routeMatch.Route.GetName(); name != "" {
 			return name
 		}
 		if tmpl, err := routeMatch.Route.GetPathTemplate(); err == nil {
 			return MakeLabelValue(tmpl)
 		}
 	}
-	return "other"
+
+	return ""
 }
 
 var invalidChars = regexp.MustCompile(`[^a-zA-Z0-9]+`)

server/server.go

@@ -139,7 +139,9 @@ func New(cfg Config) (*Server, error) {
 		RegisterInstrumentation(router)
 	}
 	httpMiddleware := []middleware.Interface{
-		middleware.Tracer{},
+		middleware.Tracer{
+			RouteMatcher: router,
+		},
 		middleware.Log{
 			Log: log,
 		},