TUN-1212: Expose tunnel_id in metrics

origin/tunnelsforha.go

@@ -0,0 +1,49 @@
+package origin
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// tunnelsForHA maps this cloudflared instance's HA connections to the tunnel IDs they serve.
+type tunnelsForHA struct {
+	sync.Mutex
+	metrics *prometheus.GaugeVec
+	entries map[uint8]string
+}
+
+// NewTunnelsForHA initializes the Prometheus metrics etc for a tunnelsForHA.
+func NewTunnelsForHA() tunnelsForHA {
+	metrics := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "tunnel_ids",
+			Help: "The ID of all tunnels (and their corresponding HA connection ID) running in this instance of cloudflared.",
+		},
+		[]string{"tunnel_id", "ha_conn_id"},
+	)
+	prometheus.MustRegister(metrics)
+
+	return tunnelsForHA{
+		metrics: metrics,
+		entries: make(map[uint8]string),
+	}
+}
+
+// Track a new tunnel ID, removing the disconnected tunnel (if any) and update metrics.
+func (t *tunnelsForHA) AddTunnelID(haConn uint8, tunnelID string) {
+	t.Lock()
+	defer t.Unlock()
+	if oldTunnelID, ok := t.entries[haConn]; ok {
+		t.metrics.WithLabelValues(oldTunnelID).Dec()
+	}
+	t.entries[haConn] = tunnelID
+	t.metrics.WithLabelValues(tunnelID, fmt.Sprintf("%v", haConn)).Inc()
+}
+
+func (t *tunnelsForHA) String() string {
+	t.Lock()
+	defer t.Unlock()
+	return fmt.Sprintf("%v", t.entries)
+}