Aleksey Shakhmatov
1d6cd95909
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
108 lines
2.7 KiB
Go
108 lines
2.7 KiB
Go
// Full observability: Prometheus metrics and OpenTelemetry tracing together.
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package main
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import (
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"context"
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"fmt"
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"log"
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"math/rand/v2"
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"net/http"
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"os"
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"os/signal"
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"strconv"
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"time"
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"git.codelab.vc/pkg/obsx"
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"go.opentelemetry.io/otel/attribute"
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"go.opentelemetry.io/otel/codes"
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)
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func main() {
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ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
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defer stop()
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// --- Tracing ---
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shutdown, err := obsx.SetupTracer(ctx, obsx.TracerConfig{
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ServiceName: "full-observability",
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ServiceVersion: "0.1.0",
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Endpoint: "localhost:4317",
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})
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if err != nil {
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log.Fatal(err)
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}
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defer func() {
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if err := shutdown(context.Background()); err != nil {
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log.Printf("tracer shutdown: %v", err)
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}
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}()
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// --- Metrics ---
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metrics := obsx.NewMetrics(obsx.MetricsConfig{
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Namespace: "myapp",
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Subsystem: "orders",
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})
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requests := metrics.Counter("requests_total", "Total requests", "method", "status")
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duration := metrics.Histogram("request_duration_seconds", "Latency", nil, "method")
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inflight := metrics.Gauge("inflight_requests", "In-flight requests")
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// --- Routes ---
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mux := http.NewServeMux()
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mux.HandleFunc("POST /orders", func(w http.ResponseWriter, r *http.Request) {
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inflight.WithLabelValues().Inc()
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defer inflight.WithLabelValues().Dec()
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start := time.Now()
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ctx, span := obsx.StartSpan(r.Context(), "HandleCreateOrder")
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defer span.End()
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orderID, err := createOrder(ctx)
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status := http.StatusCreated
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if err != nil {
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status = http.StatusInternalServerError
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span.RecordError(err)
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span.SetStatus(codes.Error, err.Error())
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http.Error(w, err.Error(), status)
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} else {
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span.SetStatus(codes.Ok, "")
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w.WriteHeader(status)
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fmt.Fprintf(w, `{"order_id": %q}`+"\n", orderID)
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}
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requests.WithLabelValues("POST", strconv.Itoa(status)).Inc()
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duration.WithLabelValues("POST").Observe(time.Since(start).Seconds())
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})
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mux.Handle("GET /metrics", metrics.Handler())
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// --- Server ---
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srv := &http.Server{Addr: ":8080", Handler: mux}
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go func() {
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<-ctx.Done()
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_ = srv.Shutdown(context.Background())
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}()
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log.Println("listening on :8080 (try POST /orders, GET /metrics)")
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if err := srv.ListenAndServe(); err != http.ErrServerClosed {
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log.Fatal(err)
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}
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}
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// createOrder simulates order creation with a child span.
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func createOrder(ctx context.Context) (string, error) {
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_, span := obsx.StartSpan(ctx, "db.InsertOrder")
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defer span.End()
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span.SetAttributes(attribute.String("db.statement", "INSERT INTO orders ..."))
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// Simulate DB latency.
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time.Sleep(time.Duration(rand.IntN(80)) * time.Millisecond)
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orderID := fmt.Sprintf("ord-%d", rand.IntN(100000))
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span.SetAttributes(attribute.String("order.id", orderID))
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return orderID, nil
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}
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