From fa900132b43faef966f11a99483dd0565e774846 Mon Sep 17 00:00:00 2001
From: Joachim Bauch <bauch@struktur.de>
Date: Thu, 6 Nov 2025 20:41:43 +0100
Subject: [PATCH] Add metrics for candidates and ICE, DTLS and PeerConnection
 states.

---
 docs/prometheus-metrics.md  |  5 +++++
 mcu_janus_events_handler.go | 12 +++++++++++-
 mcu_stats_prometheus.go     | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/docs/prometheus-metrics.md b/docs/prometheus-metrics.md
index 013c601..3ff405d 100644
--- a/docs/prometheus-metrics.md
+++ b/docs/prometheus-metrics.md
@@ -60,3 +60,8 @@ The following metrics are available:
 | `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                                   |                                   |
 | `signaling_client_rtt`                            | Histogram | 2.0.5     | The roundtrip time of WebSocket ping messages in milliseconds             |                                   |
+| `signaling_mcu_selected_local_candidate_total`    | Counter   | 2.0.5     | Total number of selected local candidates                                 | `type`, `transport`, `family`     |
+| `signaling_mcu_selected_remote_candidate_total`   | Counter   | 2.0.5     | Total number of selected local candidates                                 | `type`, `transport`, `family`     |
+| `signaling_mcu_peerconnection_state_total`        | Counter   | 2.0.5     | Total number PeerConnection states                                        | `state`, `reason`                 |
+| `signaling_mcu_ice_state_total`                   | Counter   | 2.0.5     | Total number of ICE connection states                                     | `state`                           |
+| `signaling_mcu_dtls_state_total`                  | Counter   | 2.0.5     | Total number of DTLS connection states                                    | `state`                           |
diff --git a/mcu_janus_events_handler.go b/mcu_janus_events_handler.go
index 0bb97c5..e9d6706 100644
--- a/mcu_janus_events_handler.go
+++ b/mcu_janus_events_handler.go
@@ -302,7 +302,8 @@ func (e JanusEventWebRTCDTLS) String() string {
 
 // type=16, subtype=6
 type JanusEventWebRTCPeerConnection struct {
-	Connection string `json:"connection"` // "webrtcup"
+	Connection string `json:"connection"`       // "webrtcup", "hangup"
+	Reason     string `json:"reason,omitempty"` // Only if "connection" == "hangup"
 }
 
 func (e JanusEventWebRTCPeerConnection) String() string {
@@ -737,6 +738,15 @@ func (h *JanusEventsHandler) processEvent(event JanusEvent) {
 	}
 
 	switch evt := evt.(type) {
+	case *JanusEventWebRTCICE:
+		statsJanusICEStateTotal.WithLabelValues(evt.ICE).Inc()
+	case *JanusEventWebRTCDTLS:
+		statsJanusDTLSStateTotal.WithLabelValues(evt.DTLS).Inc()
+	case *JanusEventWebRTCPeerConnection:
+		statsJanusPeerConnectionStateTotal.WithLabelValues(evt.Connection, evt.Reason).Inc()
+	case *JanusEventWebRTCSelectedPair:
+		statsJanusSelectedLocalCandidateTotal.WithLabelValues(evt.Candidates.Local.Type, evt.Candidates.Local.Transport, fmt.Sprintf("ipv%d", evt.Candidates.Local.Family)).Inc()
+		statsJanusSelectedRemoteCandidateTotal.WithLabelValues(evt.Candidates.Remote.Type, evt.Candidates.Remote.Transport, fmt.Sprintf("ipv%d", evt.Candidates.Remote.Family)).Inc()
 	case *JanusEventMediaStats:
 		h.mcu.UpdateBandwidth(event.HandleId, evt.Media, api.BandwidthFromBytes(uint64(evt.BytesSentLastSec)), api.BandwidthFromBytes(uint64(evt.BytesReceivedLastSec)))
 	}
diff --git a/mcu_stats_prometheus.go b/mcu_stats_prometheus.go
index cd063ea..a821a89 100644
--- a/mcu_stats_prometheus.go
+++ b/mcu_stats_prometheus.go
@@ -92,9 +92,44 @@ var (
 		Name:      "bandwidth",
 		Help:      "The current bandwidth in bytes per second",
 	}, []string{"direction"})
+	statsJanusSelectedLocalCandidateTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "selected_local_candidate_total",
+		Help:      "Total number of selected local candidates",
+	}, []string{"type", "transport", "family"})
+	statsJanusSelectedRemoteCandidateTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "selected_remote_candidate_total",
+		Help:      "Total number of selected remote candidates",
+	}, []string{"type", "transport", "family"})
+	statsJanusPeerConnectionStateTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "peerconnection_state_total",
+		Help:      "Total number of PeerConnections states",
+	}, []string{"state", "reason"})
+	statsJanusICEStateTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "ice_state_total",
+		Help:      "Total number of ICE connection states",
+	}, []string{"state"})
+	statsJanusDTLSStateTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "signaling",
+		Subsystem: "mcu",
+		Name:      "dtls_state_total",
+		Help:      "Total number of DTLS connection states",
+	}, []string{"state"})
 
 	janusMcuStats = []prometheus.Collector{
 		statsJanusBandwidthCurrent,
+		statsJanusSelectedLocalCandidateTotal,
+		statsJanusSelectedRemoteCandidateTotal,
+		statsJanusPeerConnectionStateTotal,
+		statsJanusICEStateTotal,
+		statsJanusDTLSStateTotal,
 	}
 
 	statsConnectedProxyBackendsCurrent = prometheus.NewGaugeVec(prometheus.GaugeOpts{