initial working version

internal/dnstt/exporter.go

@@ -0,0 +1,83 @@
+package dnstt
+
+import "github.com/prometheus/client_golang/prometheus"
+
+const namespace = "dnstt"
+
+// Exporter exposes aggregate DNSTT traffic metrics from a Collector.
+type Exporter struct {
+	collector *Collector
+
+	activeClients *prometheus.Desc
+	peakClients   *prometheus.Desc
+	queries       *prometheus.Desc
+	bytesIn       *prometheus.Desc
+	bytesOut      *prometheus.Desc
+	sessions      *prometheus.Desc
+}
+
+// NewExporter creates a Prometheus collector for DNSTT metrics.
+func NewExporter(collector *Collector) *Exporter {
+	labels := []string{"domain"}
+	return &Exporter{
+		collector: collector,
+		activeClients: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "active_clients"),
+			"Number of DNSTT client sessions observed within the active timeout window.",
+			labels,
+			nil,
+		),
+		peakClients: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "peak_clients"),
+			"Maximum concurrent active DNSTT client sessions observed.",
+			labels,
+			nil,
+		),
+		queries: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "queries_total"),
+			"Total DNSTT DNS queries observed.",
+			labels,
+			nil,
+		),
+		bytesIn: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "bytes_in_total"),
+			"Total bytes observed in DNSTT DNS queries.",
+			labels,
+			nil,
+		),
+		bytesOut: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "bytes_out_total"),
+			"Total bytes observed in DNSTT DNS responses.",
+			labels,
+			nil,
+		),
+		sessions: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "sessions_total"),
+			"Total unique DNSTT client sessions observed.",
+			labels,
+			nil,
+		),
+	}
+}
+
+// Describe sends metric descriptors to Prometheus.
+func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
+	ch <- e.activeClients
+	ch <- e.peakClients
+	ch <- e.queries
+	ch <- e.bytesIn
+	ch <- e.bytesOut
+	ch <- e.sessions
+}
+
+// Collect sends current metric values to Prometheus.
+func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
+	for _, tunnel := range e.collector.Snapshot().Tunnels {
+		ch <- prometheus.MustNewConstMetric(e.activeClients, prometheus.GaugeValue, float64(tunnel.ActiveClients), tunnel.Domain)
+		ch <- prometheus.MustNewConstMetric(e.peakClients, prometheus.GaugeValue, float64(tunnel.PeakClients), tunnel.Domain)
+		ch <- prometheus.MustNewConstMetric(e.queries, prometheus.CounterValue, float64(tunnel.TotalQueries), tunnel.Domain)
+		ch <- prometheus.MustNewConstMetric(e.bytesIn, prometheus.CounterValue, float64(tunnel.BytesIn), tunnel.Domain)
+		ch <- prometheus.MustNewConstMetric(e.bytesOut, prometheus.CounterValue, float64(tunnel.BytesOut), tunnel.Domain)
+		ch <- prometheus.MustNewConstMetric(e.sessions, prometheus.CounterValue, float64(tunnel.TotalSessions), tunnel.Domain)
+	}
+}