fix: panic when negroni middleware method is missing (#418)

httpx/assert.go

@@ -0,0 +1,27 @@
+package httpx
+
+import (
+	"net/http"
+
+	"github.com/urfave/negroni"
+)
+
+func GetResponseMeta(w http.ResponseWriter) (status, size int) {
+	switch t := w.(type) {
+	case interface {
+		Status() int
+		Written() int64
+	}:
+		return t.Status(), int(t.Written())
+	case negroni.ResponseWriter:
+		return t.Status(), t.Size()
+	}
+
+	if t, ok := w.(interface {
+		Status() int
+	}); ok {
+		return t.Status(), 0
+	}
+
+	return 0, 0
+}

metricsx/middleware.go

@@ -33,6 +33,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ory/x/httpx"
+
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/status"
 
@@ -45,7 +47,6 @@ import (
 	"github.com/ory/x/resilience"
 
 	"github.com/pborman/uuid"
-	"github.com/urfave/negroni"
 
 	analytics "github.com/ory/analytics-go/v4"
 )
@@ -245,6 +246,11 @@ func (sw *Service) ObserveMemory() {
 	}
 }
 
+type negroniMiddleware interface {
+	Size() int
+	Status() int
+}
+
 // ServeHTTP is a middleware for sending meta information to segment.
 func (sw *Service) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
 	var start time.Time
@@ -269,9 +275,7 @@ func (sw *Service) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.
 	query := sw.anonymizeQuery(r.URL.Query(), sw.salt)
 
 	// Collecting request info
-	res := rw.(negroni.ResponseWriter)
-	stat := res.Status()
-	size := res.Size()
+	stat, size := httpx.GetResponseMeta(rw)
 
 	if err := sw.c.Enqueue(analytics.Page{
 		UserId: sw.o.ClusterID,

prometheusx/metrics.go

@@ -4,10 +4,11 @@ import (
 	"net/http"
 	"strconv"
 
+	"github.com/ory/x/httpx"
+
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"github.com/urfave/negroni"
 )
 
 // Metrics prototypes
@@ -106,20 +107,17 @@ func (h Metrics) instrumentHandlerStatusBucket(next http.Handler) http.HandlerFu
 	return func(rw http.ResponseWriter, r *http.Request) {
 		next.ServeHTTP(rw, r)
 
-		res, ok := rw.(negroni.ResponseWriter)
-		if !ok {
-			return
-		}
+		status, _ := httpx.GetResponseMeta(rw)
 
 		statusBucket := "unknown"
 		switch {
-		case res.Status() >= 200 && res.Status() <= 299:
+		case status >= 200 && status <= 299:
 			statusBucket = "2xx"
-		case res.Status() >= 300 && res.Status() <= 399:
+		case status >= 300 && status <= 399:
 			statusBucket = "3xx"
-		case res.Status() >= 400 && res.Status() <= 499:
+		case status >= 400 && status <= 499:
 			statusBucket = "4xx"
-		case res.Status() >= 500 && res.Status() <= 599:
+		case status >= 500 && status <= 599:
 			statusBucket = "5xx"
 		}
 
@@ -131,10 +129,9 @@ func (h Metrics) instrumentHandlerStatusBucket(next http.Handler) http.HandlerFu
 // Instrument will instrument any http.HandlerFunc with custom metrics
 func (h Metrics) Instrument(rw http.ResponseWriter, next http.HandlerFunc, endpoint string) http.HandlerFunc {
 	labels := prometheus.Labels{}
-	res, ok := rw.(negroni.ResponseWriter)
-	if ok && res.Status() != 0 {
-		labels = prometheus.Labels{"code": strconv.Itoa(res.Status())}
-	}
+	status, _ := httpx.GetResponseMeta(rw)
+
+	labels = prometheus.Labels{"code": strconv.Itoa(status)}
 	wrapped := promhttp.InstrumentHandlerResponseSize(h.responseSize.MustCurryWith(labels), next)
 	wrapped = promhttp.InstrumentHandlerCounter(h.totalRequests.MustCurryWith(labels), wrapped)
 	wrapped = promhttp.InstrumentHandlerDuration(h.duration.MustCurryWith(labels), wrapped)