From 889ec056f21e6f8f5dc01f15783fa4986f314995 Mon Sep 17 00:00:00 2001
From: Joachim Bauch <bauch@struktur.de>
Date: Wed, 5 Nov 2025 12:11:13 +0100
Subject: [PATCH] Also expose bandwidth usage of backend servers through
 metrics.

---
 api_proxy.go               | 5 +++++
 docs/prometheus-metrics.md | 1 +
 mcu_proxy.go               | 6 ++++++
 mcu_stats_prometheus.go    | 7 +++++++
 proxy/proxy_server.go      | 8 ++++++--
 5 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/api_proxy.go b/api_proxy.go
index 8f3bd6e..7b1a5e7 100644
--- a/api_proxy.go
+++ b/api_proxy.go
@@ -321,6 +321,11 @@ type EventProxyServerBandwidth struct {
 	Incoming *float64 `json:"incoming,omitempty"`
 	// Outgoing is the bandwidth utilization for subscribers in percent.
 	Outgoing *float64 `json:"outgoing,omitempty"`
+
+	// Received is the incoming bandwidth in bytes per second.
+	Received uint64 `json:"received,omitempty"`
+	// Sent is the outgoing bandwidth in bytes per second.
+	Sent uint64 `json:"sent,omitempty"`
 }
 
 func (b *EventProxyServerBandwidth) String() string {
diff --git a/docs/prometheus-metrics.md b/docs/prometheus-metrics.md
index 5027c40..1f1c155 100644
--- a/docs/prometheus-metrics.md
+++ b/docs/prometheus-metrics.md
@@ -57,4 +57,5 @@ The following metrics are available:
 | `signaling_backend_client_requests_errors_total`  | Counter   | 2.0.3     | The total number of backend client requests that had an error             | `backend`, `error`                |
 | `signaling_mcu_bandwidth`                         | Gauge     | 2.0.5     | The current bandwidth in bytes per second                                 | `direction`                       |
 | `signaling_mcu_backend_usage`                     | Gauge     | 2.0.5     | The current usage of signaling proxy backends in percent                  | `url`, `direction`                |
+| `signaling_mcu_backend_bandwidth`                 | Gauge     | 2.0.5     | The current bandwidth of signaling proxy backends in bytes per second     | `url`, `direction`                |
 | `signaling_proxy_load`                            | Gauge     | 2.0.5     | The current load of the signaling proxy                                   |                                   |
diff --git a/mcu_proxy.go b/mcu_proxy.go
index 461be23..b46d703 100644
--- a/mcu_proxy.go
+++ b/mcu_proxy.go
@@ -416,6 +416,8 @@ func newMcuProxyConnection(proxy *mcuProxy, baseUrl string, ip net.IP, token str
 	statsProxyBackendLoadCurrent.WithLabelValues(conn.url.String()).Set(0)
 	statsProxyUsageCurrent.WithLabelValues(conn.url.String(), "incoming").Set(0)
 	statsProxyUsageCurrent.WithLabelValues(conn.url.String(), "outgoing").Set(0)
+	statsProxyBandwidthCurrent.WithLabelValues(conn.url.String(), "incoming").Set(0)
+	statsProxyBandwidthCurrent.WithLabelValues(conn.url.String(), "outgoing").Set(0)
 	return conn, nil
 }
 
@@ -754,6 +756,8 @@ func (c *mcuProxyConnection) closeIfEmpty() bool {
 		statsProxyBackendLoadCurrent.DeleteLabelValues(c.url.String())
 		statsProxyUsageCurrent.DeleteLabelValues(c.url.String(), "incoming")
 		statsProxyUsageCurrent.DeleteLabelValues(c.url.String(), "outgoing")
+		statsProxyBandwidthCurrent.DeleteLabelValues(c.url.String(), "incoming")
+		statsProxyBandwidthCurrent.DeleteLabelValues(c.url.String(), "outgoing")
 
 		c.proxy.removeConnection(c)
 	}()
@@ -1090,6 +1094,8 @@ func (c *mcuProxyConnection) processEvent(msg *ProxyServerMessage) {
 		c.bandwidth.Store(event.Bandwidth)
 		statsProxyBackendLoadCurrent.WithLabelValues(c.url.String()).Set(float64(event.Load))
 		if bw := event.Bandwidth; bw != nil {
+			statsProxyBandwidthCurrent.WithLabelValues(c.url.String(), "incoming").Set(float64(bw.Received))
+			statsProxyBandwidthCurrent.WithLabelValues(c.url.String(), "outgoing").Set(float64(bw.Sent))
 			if bw.Incoming != nil {
 				statsProxyUsageCurrent.WithLabelValues(c.url.String(), "incoming").Set(*bw.Incoming)
 			} else {
diff --git a/mcu_stats_prometheus.go b/mcu_stats_prometheus.go
index d1df618..cd063ea 100644
--- a/mcu_stats_prometheus.go
+++ b/mcu_stats_prometheus.go
@@ -115,6 +115,12 @@ var (
 		Name:      "backend_usage",
 		Help:      "The current usage of signaling proxy backends in percent",
 	}, []string{"url", "direction"})
+	statsProxyBandwidthCurrent = prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "backend_bandwidth",
+		Help:      "The current bandwidth of signaling proxy backends in bytes per second",
+	}, []string{"url", "direction"})
 	statsProxyNobackendAvailableTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
 		Namespace: "signaling",
 		Subsystem: "mcu",
@@ -126,6 +132,7 @@ var (
 		statsConnectedProxyBackendsCurrent,
 		statsProxyBackendLoadCurrent,
 		statsProxyUsageCurrent,
+		statsProxyBandwidthCurrent,
 		statsProxyNobackendAvailableTotal,
 	}
 )
diff --git a/proxy/proxy_server.go b/proxy/proxy_server.go
index b38b190..93f1f42 100644
--- a/proxy/proxy_server.go
+++ b/proxy/proxy_server.go
@@ -503,8 +503,12 @@ func (s *ProxyServer) newLoadEvent(load uint64, incoming uint64, outgoing uint64
 	}
 	maxIncoming := s.maxIncoming.Load()
 	maxOutgoing := s.maxOutgoing.Load()
-	if maxIncoming > 0 || maxOutgoing > 0 {
-		msg.Event.Bandwidth = &signaling.EventProxyServerBandwidth{}
+	if maxIncoming > 0 || maxOutgoing > 0 || incoming != 0 || outgoing != 0 {
+		// Values should be sent in bytes per second.
+		msg.Event.Bandwidth = &signaling.EventProxyServerBandwidth{
+			Received: incoming / 8,
+			Sent:     outgoing / 8,
+		}
 		if maxIncoming > 0 {
 			value := float64(incoming) / float64(maxIncoming) * 100
 			msg.Event.Bandwidth.Incoming = &value