Correctly instrument websocket handshakes

Part of weaveworks/monitoring#82

vendor/github.com/weaveworks/common/middleware/instrument.go

@@ -19,16 +19,25 @@ type Instrument struct {
 	Duration *prometheus.HistogramVec
 }
 
-func isWSHandshakeRequest(req *http.Request) bool {
-	return strings.ToLower(req.Header.Get("Upgrade")) == "websocket" &&
-		strings.ToLower(req.Header.Get("Connection")) == "upgrade"
+// IsWSHandshakeRequest returns true if the given request is a websocket handshake request.
+func IsWSHandshakeRequest(req *http.Request) bool {
+	if strings.ToLower(req.Header.Get("Upgrade")) == "websocket" {
+		// Connection header values can be of form "foo, bar, ..."
+		parts := strings.Split(strings.ToLower(req.Header.Get("Connection")), ",")
+		for _, part := range parts {
+			if strings.TrimSpace(part) == "upgrade" {
+				return true
+			}
+		}
+	}
+	return false
 }
 
 // Wrap implements middleware.Interface
 func (i Instrument) Wrap(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		begin := time.Now()
-		isWS := strconv.FormatBool(isWSHandshakeRequest(r))
+		isWS := strconv.FormatBool(IsWSHandshakeRequest(r))
 		interceptor := &interceptor{ResponseWriter: w, statusCode: http.StatusOK}
 		route := i.getRouteName(r)
 		next.ServeHTTP(interceptor, r)

vendor/manifest

@@ -1361,7 +1361,7 @@
 			"importpath": "github.com/weaveworks/common",
 			"repository": "https://github.com/weaveworks/common",
 			"vcs": "git",
-			"revision": "5edbff9f695b090e16bbb90dd89b83b70178c49e",
+			"revision": "cc20acf03ebf74be0facaae4259dff6cde01ce77",
 			"branch": "master",
 			"notests": true
 		},