controlclient: add timing metrics for control requests

Updates #26869

control/controlclient/direct.go

@@ -676,7 +676,9 @@ func (c *Direct) doLogin(ctx context.Context, opt loginOpt) (mustRegen bool, new
 	addLBHeader(req, request.OldNodeKey)
 	addLBHeader(req, request.NodeKey)
 
+	start := time.Now()
 	res, err := httpc.Do(req)
+	loginLatencies.Observe(time.Since(start).Seconds())
 	if err != nil {
 		return regen, opt.URL, nil, fmt.Errorf("register request: %w", err)
 	}
@@ -964,7 +966,9 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 	}
 	addLBHeader(req, nodeKey)
 
+	start := time.Now()
 	res, err := httpc.Do(req)
+	initialMapRequestLatencies.Observe(time.Since(start).Seconds())
 	if err != nil {
 		vlogf("netmap: Do: %v", err)
 		return err
@@ -1322,6 +1326,7 @@ func (c *Direct) answerPing(pr *tailcfg.PingRequest) {
 		c.logf("invalid PingRequest with no URL")
 		return
 	}
+	start := time.Now()
 	switch pr.Types {
 	case "":
 		answerHeadPing(c.logf, httpc, pr)
@@ -1334,6 +1339,7 @@ func (c *Direct) answerPing(pr *tailcfg.PingRequest) {
 		answerC2NPing(c.logf, c.c2nHandler, httpc, pr)
 		return
 	}
+	answerPingLatencies.Observe(time.Since(start).Seconds())
 	for _, t := range strings.Split(pr.Types, ",") {
 		switch pt := tailcfg.PingType(t); pt {
 		case tailcfg.PingTSMP, tailcfg.PingDisco, tailcfg.PingICMP, tailcfg.PingPeerAPI:
@@ -1638,7 +1644,9 @@ func (c *Direct) ReportHealthChange(w *health.Warnable, us *health.UnhealthyStat
 	// Best effort, no logging:
 	ctx, cancel := context.WithTimeout(c.closedCtx, 5*time.Second)
 	defer cancel()
+	start := time.Now()
 	res, err := np.post(ctx, "/machine/update-health", nodeKey, req)
+	updateHealthLatencies.Observe(time.Since(start).Seconds())
 	if err != nil {
 		return
 	}

control/controlclient/metrics.go

@@ -0,0 +1,39 @@
+package controlclient
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	loginLatencies = promauto.NewHistogram(prometheus.HistogramOpts{
+		Name: "controlclient_login_latency_seconds",
+		Help: "Control login time",
+		// 15 buckets from 10ms to 1m.
+		Buckets: prometheus.ExponentialBucketsRange(0.01, 60, 15)},
+	)
+	dialLatencies = promauto.NewHistogram(prometheus.HistogramOpts{
+		Name: "controlclient_dial_latency_seconds",
+		Help: "Control dial time",
+		// 15 buckets from 10ms to 1m.
+		Buckets: prometheus.ExponentialBucketsRange(0.01, 60, 15)},
+	)
+	initialMapRequestLatencies = promauto.NewHistogram(prometheus.HistogramOpts{
+		Name: "controlclient_initial_map_request_latency_seconds",
+		Help: "Initial map request/response time",
+		// 15 buckets from 10ms to 1m.
+		Buckets: prometheus.ExponentialBucketsRange(0.01, 60, 15)},
+	)
+	updateHealthLatencies = promauto.NewHistogram(prometheus.HistogramOpts{
+		Name: "controlclient_update_health_latency_seconds",
+		Help: "Update health request/response time",
+		// 15 buckets from 10ms to 1m.
+		Buckets: prometheus.ExponentialBucketsRange(0.01, 60, 15)},
+	)
+	answerPingLatencies = promauto.NewHistogram(prometheus.HistogramOpts{
+		Name: "controlclient_answer_ping_latency_seconds",
+		Help: "Answer ping request/response time",
+		// 15 buckets from 10ms to 1m.
+		Buckets: prometheus.ExponentialBucketsRange(0.01, 60, 15)},
+	)
+)

control/controlclient/noise.go

@@ -239,7 +239,9 @@ func (nc *NoiseClient) getConn(ctx context.Context) (*noiseconn.Conn, error) {
 		// which was canceled is our context and retry if our context is still
 		// valid.
 		conn, err, _ := nc.sfDial.Do(struct{}{}, func() (*noiseconn.Conn, error) {
+			start := time.Now()
 			c, err := nc.dial(ctx)
+			dialLatencies.Observe(time.Since(start).Seconds())
 			if err != nil {
 				if ctx.Err() != nil {
 					return nil, contextErr{ctx.Err()}