75 lines
2.6 KiB
Go
75 lines
2.6 KiB
Go
package prometheus
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import (
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// Hybrid instrumentation rationale: direct client_golang instrumentation
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// lives in app/webrtc/metrics.go (hot-path counters and histograms);
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// this file owns the snapshot-style gauges. See the design doc at
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// docs/design/2026-05-03-datarhei-dragon-fork-webrtc-prometheus-metrics-design.md.
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"github.com/prometheus/client_golang/prometheus"
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)
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// WebRTCStats is a point-in-time snapshot of the WebRTC subsystem state.
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// Populated by Handler.Stats() in app/webrtc and consumed by the collector
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// at scrape time.
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type WebRTCStats struct {
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StreamCount int
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PeersByStream map[string]int
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UDPPortsInUse int
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}
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// WebRTCStatsSource is implemented by app/webrtc.Handler (via its Stats()
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// method). The interface lives here so prometheus/ does not import app/webrtc,
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// keeping the dependency arrow one-directional.
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type WebRTCStatsSource interface {
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Stats() WebRTCStats
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}
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type webrtcCollector struct {
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core string
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source WebRTCStatsSource
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activeStreamsDesc *prometheus.Desc
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activePeersDesc *prometheus.Desc
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udpPortsInUseDesc *prometheus.Desc
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}
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// NewWebRTCCollector returns a prometheus.Collector that emits three gauge
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// metrics at scrape time by calling source.Stats(). Register it with the
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// shared Metrics registry before the /metrics endpoint starts serving.
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func NewWebRTCCollector(core string, source WebRTCStatsSource) prometheus.Collector {
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cl := prometheus.Labels{"core": core}
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return &webrtcCollector{
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core: core,
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source: source,
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activeStreamsDesc: prometheus.NewDesc(
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"dragonfork_webrtc_active_streams",
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"Streams currently registered (processes with webrtc.enabled=true running).",
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nil, cl,
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),
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activePeersDesc: prometheus.NewDesc(
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"dragonfork_webrtc_active_peers",
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"Currently subscribed WHEP peers per stream.",
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[]string{"stream_id"}, cl,
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),
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udpPortsInUseDesc: prometheus.NewDesc(
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"dragonfork_webrtc_udp_ports_in_use",
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"UDP ports currently allocated (2 per active stream).",
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nil, cl,
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),
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}
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}
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func (c *webrtcCollector) Describe(ch chan<- *prometheus.Desc) {
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ch <- c.activeStreamsDesc
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ch <- c.activePeersDesc
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ch <- c.udpPortsInUseDesc
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}
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func (c *webrtcCollector) Collect(ch chan<- prometheus.Metric) {
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stats := c.source.Stats()
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ch <- prometheus.MustNewConstMetric(c.activeStreamsDesc, prometheus.GaugeValue, float64(stats.StreamCount))
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ch <- prometheus.MustNewConstMetric(c.udpPortsInUseDesc, prometheus.GaugeValue, float64(stats.UDPPortsInUse))
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for streamID, count := range stats.PeersByStream {
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ch <- prometheus.MustNewConstMetric(c.activePeersDesc, prometheus.GaugeValue, float64(count), streamID)
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}
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}
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