Observabilitas & Telemetri

distlimit memiliki arsitektur telemetri pluggable via interface metrics.Observer. Saat dinonaktifkan, subsistem telemetri ini memberikan overhead memori 0 B/op dan latensi nol.

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📊 Integrasi Prometheus (metrics/prometheus)

Collector Prometheus (distprom.Observer) mengekspor metrik untuk jumlah evaluasi, latensi eksekusi, dan event failover circuit breaker.

Instalasi

go get github.com/prometheus/client_golang

Setup Kode Lengkap

package main

import (
  "net/http"
  "time"

  "github.com/balramadan/distlimit"
  "github.com/balramadan/distlimit/algorithm/tokenbucket"
  "github.com/balramadan/distlimit/driver/memory"
  distprom "github.com/balramadan/distlimit/metrics/prometheus"
  distlimitnethttp "github.com/balramadan/distlimit/middleware/nethttp"
  "github.com/prometheus/client_golang/prometheus/promhttp"
)

func main() {
  memDriver := memory.New(5 * time.Minute)

  // 1. Inisialisasi Prometheus Observer
  promObserver := distprom.NewObserver(
    distprom.WithNamespace("api_gateway"),
    distprom.WithSubsystem("rate_limiter"),
  )

  // 2. Pasangkan Observer ke Limiter
  limiter, _ := distlimit.New(
    memDriver,
    distlimit.WithLimit(100),
    distlimit.WithWindow(1*time.Minute),
    distlimit.WithAlgorithm(tokenbucket.New()),
    distlimit.WithMetricObserver(promObserver),
  )

  mux := http.NewServeMux()

  // 3. Aktifkan Route Labeling pada Middleware
  apiHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("ok"))
  })
  mux.Handle("/api/v1/users", distlimitnethttp.New(
    limiter,
    distlimitnethttp.WithRouteLabeling(true),
  )(apiHandler))

  // 4. Sediakan Endpoint Metrics untuk Scraper Prometheus
  mux.Handle("/metrics", promhttp.Handler())

  http.ListenAndServe(":8080", mux)
}

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Metrik Prometheus yang Diekspor

Nama Metrik	Tipe	Label	Deskripsi
distlimit_requests_total	Counter	status, driver, algorithm, route	Total evaluasi rate limit. Nilai status: allowed atau blocked.
distlimit_evaluation_duration_seconds	Histogram	driver, algorithm, route	Latensi eksekusi internal evaluasi rate limit dalam detik.
distlimit_hybrid_fallback_total	Counter	driver	Total kegagalan Redis di mana Driver Hybrid beralih ke memori.

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🔭 Integrasi OpenTelemetry (metrics/otel)

Observer OpenTelemetry (distotel.Observer) mencatat counter dan histogram menggunakan OTel Meter Provider standar.

Instalasi

go get go.opentelemetry.io/otel

Setup Kode Lengkap

package main

import (
  "time"

  "github.com/balramadan/distlimit"
  "github.com/balramadan/distlimit/algorithm/tokenbucket"
  "github.com/balramadan/distlimit/driver/memory"
  distotel "github.com/balramadan/distlimit/metrics/otel"
  "go.opentelemetry.io/otel"
)

func main() {
  memDriver := memory.New(5 * time.Minute)

  // Inisialisasi OpenTelemetry Observer menggunakan MeterProvider global
  otelObserver := distotel.NewObserver(
    distotel.WithMeterProvider(otel.GetMeterProvider()),
  )

  limiter, _ := distlimit.New(
    memDriver,
    distlimit.WithLimit(100),
    distlimit.WithWindow(1*time.Minute),
    distlimit.WithAlgorithm(tokenbucket.New()),
    distlimit.WithMetricObserver(otelObserver),
  )

  _ = limiter
}

---

Jaminan Zero-Allocation

Saat tidak ada observer yang diberikan (atau saat menggunakan metrics.NewNoopObserver()), distlimit sepenuhnya melompati alokasi string dan timestamp.

Hasil Benchmark

BenchmarkLimiter_NoObserver-2   322239   3223 ns/op   0 B/op   0 allocs/op

Key Takeaway Performa: Mengaktifkan rate limiting dengan observabilitas yang dinonaktifkan menghasilkan 0 B/op alokasi memori dan tidak menimbulkan tekanan Garbage Collection pada beban tinggi.