feat(server): запуск планировщика, /metrics, graceful shutdown

cmd/server/main.go

@@ -2,9 +2,13 @@ package main
 
 import (
 	"context"
+	"errors"
 	"log"
 	"net/http"
+	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/jackc/pgx/v5/pgxpool"
@@ -13,8 +17,11 @@ import (
 	"github.com/vasyakrg/dns-autoresolver/internal/auth"
 	"github.com/vasyakrg/dns-autoresolver/internal/config"
 	"github.com/vasyakrg/dns-autoresolver/internal/crypto"
+	"github.com/vasyakrg/dns-autoresolver/internal/metrics"
+	"github.com/vasyakrg/dns-autoresolver/internal/notify"
 	"github.com/vasyakrg/dns-autoresolver/internal/provider/registry"
 	"github.com/vasyakrg/dns-autoresolver/internal/provider/selectel"
+	"github.com/vasyakrg/dns-autoresolver/internal/scheduler"
 	"github.com/vasyakrg/dns-autoresolver/internal/service"
 	"github.com/vasyakrg/dns-autoresolver/internal/store"
 	"github.com/vasyakrg/dns-autoresolver/internal/web"
@@ -24,6 +31,16 @@ import (
 // user must re-authenticate.
 const sessionTTL = 720 * time.Hour
 
+// schedulerTick is how often the in-process scheduler checks for due project
+// schedules. Individual projects only actually run when their own
+// schedules.interval_seconds has elapsed (see internal/store ListDueSchedules) —
+// this is just the polling granularity.
+const schedulerTick = time.Minute
+
+// shutdownTimeout bounds how long graceful shutdown waits for in-flight HTTP
+// requests to finish before forcing the listener closed.
+const shutdownTimeout = 10 * time.Second
+
 // isAPIPath reports whether path must be routed to the API router rather
 // than the SPA. "/api" (no trailing slash) counts as an API path too —
 // only strings.HasPrefix(path, "/api/") would otherwise miss it and fall
@@ -33,7 +50,9 @@ func isAPIPath(path string) bool {
 }
 
 func main() {
-	ctx := context.Background()
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
 	cfg, err := config.Load()
 	if err != nil {
 		log.Fatalf("config: %v", err)
@@ -58,7 +77,14 @@ func main() {
 	reg.Register(selectel.New())
 
 	svc := service.New(st, st, reg, cipher)
-	a := &api.API{Svc: svc, Store: st, Cipher: cipher, Reg: reg, Auth: st, Sessions: sessions}
+
+	m := metrics.New()
+	dispatcher := notify.NewDispatcher(st, cipher)
+
+	a := &api.API{
+		Svc: svc, Store: st, Cipher: cipher, Reg: reg, Auth: st, Sessions: sessions,
+		Schedule: st, Dispatch: dispatcher,
+	}
 	apiRouter := api.NewRouter(a)
 
 	webHandler, err := web.Handler()
@@ -66,20 +92,53 @@ func main() {
 		log.Printf("web: static UI unavailable: %v", err)
 	}
 
+	// The scheduler only checks and notifies — it never applies zone changes
+	// (Apply stays a manual, explicit API call). Its own errors are logged
+	// internally and never stop the loop; ctx cancellation (signal) is the
+	// only thing that ends Run.
+	sched := scheduler.New(st, svc, dispatcher, m)
+	go sched.Run(ctx, schedulerTick)
+
 	mux := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if isAPIPath(r.URL.Path) {
+		switch {
+		case r.URL.Path == "/metrics":
+			// Public by design (no auth) — Metrics.Handler only ever exposes
+			// aggregate counters/gauges, never per-domain or secret data.
+			m.Handler().ServeHTTP(w, r)
+		case isAPIPath(r.URL.Path):
 			apiRouter.ServeHTTP(w, r)
-			return
-		}
-		if webHandler != nil {
+		case webHandler != nil:
 			webHandler.ServeHTTP(w, r)
-			return
+		default:
+			http.NotFound(w, r)
 		}
-		http.NotFound(w, r)
 	})
 
-	log.Printf("listening on %s", cfg.ListenAddr)
-	if err := http.ListenAndServe(cfg.ListenAddr, mux); err != nil {
-		log.Fatal(err)
+	srv := &http.Server{Addr: cfg.ListenAddr, Handler: mux}
+
+	serveErr := make(chan error, 1)
+	go func() {
+		log.Printf("listening on %s", cfg.ListenAddr)
+		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			serveErr <- err
+			return
+		}
+		serveErr <- nil
+	}()
+
+	select {
+	case <-ctx.Done():
+		log.Printf("shutdown signal received, draining connections (timeout %s)", shutdownTimeout)
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), shutdownTimeout)
+		defer cancel()
+		if err := srv.Shutdown(shutdownCtx); err != nil {
+			log.Printf("server: graceful shutdown failed: %v", err)
+		}
+		<-serveErr
+		log.Printf("server stopped")
+	case err := <-serveErr:
+		if err != nil {
+			log.Fatalf("server: %v", err)
+		}
 	}
 }