marcusDenslow
31b8e82e47
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Default prometheus.DefBuckets bottoms out at 5ms, which made every route's p95 collapse to 4.75ms (histogram_quantile interpolation within the smallest bucket). Custom buckets from 100µs to 5s now distinguish microsecond-fast routes (health) from slower ones (stripe-backed cart endpoints). Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
package middleware
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import (
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"net/http"
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"strconv"
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"time"
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"github.com/go-chi/chi/v5"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promauto"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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var (
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httpRequestsTotal = promauto.NewCounterVec(
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prometheus.CounterOpts{
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Name: "http_requests_total",
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Help: "Total HTTP requests processed, labeled by method, route, and status",
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},
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[]string{"method", "route", "status"},
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)
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httpRequestDuration = promauto.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "http_request_duration_seconds",
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Help: "HTTP request latency in seconds, labeled by method and route",
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Buckets: []float64{.0001, .0005, .001, .0025, .005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5},
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},
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[]string{"method", "route"},
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)
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)
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// Metrics records request count and latency for every request
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func Metrics(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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start := time.Now()
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wrapped := newResponseWriter(w)
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next.ServeHTTP(wrapped, r)
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route := chi.RouteContext(r.Context()).RoutePattern()
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if route == "" {
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route = "unknown"
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}
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duration := time.Since(start).Seconds()
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status := strconv.Itoa(wrapped.statusCode)
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httpRequestsTotal.WithLabelValues(r.Method, route, status).Inc()
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httpRequestDuration.WithLabelValues(r.Method, route).Observe(duration)
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})
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}
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// MetricsHandler returns the Prometheus scrape endpoint
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func MetricsHandler() http.Handler {
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return promhttp.Handler()
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}
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