Initial commit: stats-gateway gRPC service + dashboard + CLI

internal/probes/probes.go

@@ -0,0 +1,72 @@
+package probes
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httptrace"
+	"time"
+)
+
+// Result holds timing measurements from a single HTTP probe.
+type Result struct {
+	Node           string // populated by storage on read; ignored by InsertSample (uses separate arg)
+	URL            string
+	HTTPLatencyMs  float64
+	TCPRttMs       float64
+	DNSResolveMs   float64
+	TLSHandshakeMs float64
+	ThroughputKbps int64
+	Timestamp      time.Time
+}
+
+// ProbeHTTP performs an HTTP HEAD request to url, recording timing via httptrace.
+func ProbeHTTP(ctx context.Context, url string) (*Result, error) {
+	r := &Result{URL: url, Timestamp: time.Now().UTC()}
+
+	var dnsStart, connStart, tlsStart time.Time
+	trace := &httptrace.ClientTrace{
+		DNSStart: func(_ httptrace.DNSStartInfo) { dnsStart = time.Now() },
+		DNSDone: func(_ httptrace.DNSDoneInfo) {
+			if !dnsStart.IsZero() {
+				r.DNSResolveMs = float64(time.Since(dnsStart).Microseconds()) / 1000
+			}
+		},
+		ConnectStart: func(_, _ string) { connStart = time.Now() },
+		ConnectDone: func(_, _ string, _ error) {
+			if !connStart.IsZero() {
+				r.TCPRttMs = float64(time.Since(connStart).Microseconds()) / 1000
+			}
+		},
+		TLSHandshakeStart: func() { tlsStart = time.Now() },
+		TLSHandshakeDone: func(_ tls.ConnectionState, _ error) {
+			if !tlsStart.IsZero() {
+				r.TLSHandshakeMs = float64(time.Since(tlsStart).Microseconds()) / 1000
+			}
+		},
+	}
+
+	req, err := http.NewRequestWithContext(httptrace.WithClientTrace(ctx, trace), "HEAD", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("new request: %w", err)
+	}
+
+	client := &http.Client{
+		Timeout: 10 * time.Second,
+		Transport: &http.Transport{
+			DialContext: (&net.Dialer{Timeout: 5 * time.Second}).DialContext,
+		},
+	}
+
+	start := time.Now()
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("http: %w", err)
+	}
+	defer resp.Body.Close()
+	r.HTTPLatencyMs = float64(time.Since(start).Microseconds()) / 1000
+
+	return r, nil
+}