rod
89 lines
2.3 KiB
Go
89 lines
2.3 KiB
Go
package main
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import (
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"encoding/json"
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"log/slog"
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"net/http"
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"os"
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"strconv"
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"time"
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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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reqTotal = promauto.NewCounterVec(prometheus.CounterOpts{
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Name: "http_requests_total",
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Help: "Total number of HTTP requests.",
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}, []string{"method", "path", "status"})
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reqDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
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Name: "http_request_duration_seconds",
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Help: "HTTP request latency in seconds.",
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Buckets: prometheus.DefBuckets,
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}, []string{"method", "path"})
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)
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func main() {
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env := getenv("APP_ENV", "dev")
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version := getenv("APP_VERSION", "unknown")
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port := getenv("PORT", "8080")
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logLevel := slog.LevelInfo
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if getenv("LOG_LEVEL", "info") == "debug" {
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logLevel = slog.LevelDebug
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}
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slog.SetDefault(slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: logLevel})))
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mux := http.NewServeMux()
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mux.Handle("/metrics", promhttp.Handler())
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mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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})
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mux.HandleFunc("/", instrument(func(w http.ResponseWriter, r *http.Request) {
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w.Header().Set("Content-Type", "application/json")
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json.NewEncoder(w).Encode(map[string]string{
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"env": env,
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"version": version,
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})
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}))
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slog.Info("listening", "port", port, "env", env, "version", version)
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if err := http.ListenAndServe(":"+port, mux); err != nil {
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slog.Error("server failed", "err", err)
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os.Exit(1)
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}
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}
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func instrument(next http.HandlerFunc) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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rw := &statusWriter{ResponseWriter: w, status: http.StatusOK}
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start := time.Now()
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next(rw, r)
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dur := time.Since(start).Seconds()
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status := strconv.Itoa(rw.status)
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reqTotal.WithLabelValues(r.Method, r.URL.Path, status).Inc()
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reqDuration.WithLabelValues(r.Method, r.URL.Path).Observe(dur)
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slog.Debug("request", "method", r.Method, "path", r.URL.Path, "status", rw.status, "duration", dur)
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}
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}
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type statusWriter struct {
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http.ResponseWriter
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status int
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}
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func (sw *statusWriter) WriteHeader(code int) {
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sw.status = code
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sw.ResponseWriter.WriteHeader(code)
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}
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func getenv(key, fallback string) string {
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if v := os.Getenv(key); v != "" {
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return v
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}
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return fallback
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}
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