main.go

package main

import (
	"context"
	"flag"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"prometheus-s3-exporter/pkg/config"
	"prometheus-s3-exporter/pkg/exporter"

	"github.com/prometheus/client_golang/prometheus/promhttp"
)

var (
	version = "dev"
	commit  = ""
	date    = ""
)

func main() {
	cfgPath := flag.String("config", "config.toml", "Path to TOML config file")
	listen := flag.String("listen", "", "Override listen address from config (e.g. :9877)")
	flag.Parse()

	log.Printf("prometheus-s3-exporter version=%s commit=%s date=%s", version, commit, date)

	cfg, err := config.Load(*cfgPath)
	if err != nil {
		log.Fatalf("failed to load config: %v", err)
	}
	if *listen != "" {
		cfg.Server.ListenAddress = *listen
	}

	exp, err := exporter.NewManager(cfg)
	if err != nil {
		log.Fatalf("failed to init exporter: %v", err)
	}
	// Start background collectors
	exp.Start()
	defer exp.Stop()

	mux := http.NewServeMux()
	mux.Handle(cfg.Server.MetricsPath, promhttp.Handler())
	mux.HandleFunc("/-/ready", func(w http.ResponseWriter, r *http.Request) {
		if exp.Ready() {
			w.WriteHeader(http.StatusOK)
			_, _ = w.Write([]byte("ok"))
			return
		}
		w.WriteHeader(http.StatusServiceUnavailable)
		_, _ = w.Write([]byte("not ready"))
	})
	mux.HandleFunc("/-/healthy", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("ok"))
	})

	srv := &http.Server{Addr: cfg.Server.ListenAddress, Handler: mux}

	go func() {
		log.Printf("listening on %s, metrics at %s", cfg.Server.ListenAddress, cfg.Server.MetricsPath)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("http server error: %v", err)
		}
	}()

	// Graceful shutdown
	sigc := make(chan os.Signal, 1)
	signal.Notify(sigc, os.Interrupt, syscall.SIGTERM)
	<-sigc
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := srv.Shutdown(ctx); err != nil {
		log.Printf("server shutdown error: %v", err)
	}
}