Add metrics about client bytes/messages sent/received.

client.go

@@ -26,6 +26,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"io"
 	"net"
 	"strconv"
 	"strings"
@@ -344,6 +345,7 @@ func (c *Client) ReadPump() {
 		if msg == "" {
 			return nil
 		}
+		statsClientBytesTotal.WithLabelValues("incoming").Add(float64(len(msg)))
 		if ts, err := strconv.ParseInt(msg, 10, 64); err == nil {
 			rtt := now.Sub(time.Unix(0, ts))
 			if c.logRTT {
@@ -406,6 +408,8 @@ func (c *Client) ReadPump() {
 			break
 		}
 
+		statsClientBytesTotal.WithLabelValues("incoming").Add(float64(decodeBuffer.Len()))
+		statsClientMessagesTotal.WithLabelValues("incoming").Inc()
 		c.messageChan <- decodeBuffer
 	}
 }
@@ -425,16 +429,33 @@ func (c *Client) processMessages() {
 	c.doClose()
 }
 
+type counterWriter struct {
+	w       io.Writer
+	counter *int
+}
+
+func (w *counterWriter) Write(p []byte) (int, error) {
+	written, err := w.w.Write(p)
+	if written > 0 {
+		*w.counter += written
+	}
+	return written, err
+}
+
 func (c *Client) writeInternal(message json.Marshaler) bool {
 	var closeData []byte
 
 	c.conn.SetWriteDeadline(time.Now().Add(writeWait)) // nolint
 	writer, err := c.conn.NextWriter(websocket.TextMessage)
+	var written int
 	if err == nil {
 		if m, ok := (any(message)).(easyjson.Marshaler); ok {
-			_, err = easyjson.MarshalToWriter(m, writer)
+			written, err = easyjson.MarshalToWriter(m, writer)
 		} else {
-			err = json.NewEncoder(writer).Encode(message)
+			err = json.NewEncoder(&counterWriter{
+				w:       writer,
+				counter: &written,
+			}).Encode(message)
 		}
 	}
 	if err == nil {
@@ -454,6 +475,9 @@ func (c *Client) writeInternal(message json.Marshaler) bool {
 		closeData = websocket.FormatCloseMessage(websocket.CloseInternalServerErr, "")
 		goto close
 	}
+
+	statsClientBytesTotal.WithLabelValues("outgoing").Add(float64(written))
+	statsClientMessagesTotal.WithLabelValues("outgoing").Inc()
 	return true
 
 close:
@@ -542,6 +566,7 @@ func (c *Client) sendPing() bool {
 		return false
 	}
 
+	statsClientBytesTotal.WithLabelValues("outgoing").Add(float64(len(msg)))
 	return true
 }
 

client_stats_prometheus.go

@@ -39,10 +39,24 @@ var (
 		Help:      "The roundtrip time of WebSocket ping messages in milliseconds",
 		Buckets:   prometheus.ExponentialBucketsRange(1, 30000, 50),
 	})
+	statsClientBytesTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "client",
+		Name:      "bytes_total",
+		Help:      "The total number of bytes sent to or received by clients",
+	}, []string{"direction"})
+	statsClientMessagesTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "client",
+		Name:      "messages_total",
+		Help:      "The total number of messages sent to or received by clients",
+	}, []string{"direction"})
 
 	clientStats = []prometheus.Collector{
 		statsClientCountries,
 		statsClientRTT,
+		statsClientBytesTotal,
+		statsClientMessagesTotal,
 	}
 )
 

client_test.go

@@ -0,0 +1,46 @@
+/**
+ * Standalone signaling server for the Nextcloud Spreed app.
+ * Copyright (C) 2025 struktur AG
+ *
+ * @author Joachim Bauch <bauch@struktur.de>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package signaling
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCounterWriter(t *testing.T) {
+	assert := assert.New(t)
+
+	var b bytes.Buffer
+	var written int
+	w := &counterWriter{
+		w:       &b,
+		counter: &written,
+	}
+	if count, err := w.Write(nil); assert.NoError(err) && assert.EqualValues(0, count) {
+		assert.EqualValues(0, written)
+	}
+	if count, err := w.Write([]byte("foo")); assert.NoError(err) && assert.EqualValues(3, count) {
+		assert.EqualValues(3, written)
+	}
+}

docs/prometheus-metrics.md

@@ -72,3 +72,5 @@ The following metrics are available:
 | `signaling_mcu_media_retransmissions_total`       | Counter   | 2.0.5     | The total number of received retransmissions                              | `media`                           |
 | `signaling_mcu_media_bytes_total`                 | Counter   | 2.0.5     | The total number of media bytes sent / received                           | `media`, `direction`              |
 | `signaling_mcu_media_lost_total`                  | Counter   | 2.0.5     | The total number of lost media packets                                    | `media`, `origin`                 |
+| `signaling_client_bytes_total`                    | Counter   | 2.0.5     | The total number of bytes sent to or received by clients                  | `direction`                       |
+| `signaling_client_messages_total`                 | Counter   | 2.0.5     | The total number of messages sent to or received by clients               | `direction`                       |