Рыба проекта. Минимальная функциональность

pkg/adapters/healthz/healthz.go

@@ -0,0 +1,67 @@
+package healthz
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"sync/atomic"
+	"time"
+)
+
+// Server is a minimal HTTP health check server.
+type Server struct {
+	listener     net.Listener
+	server       *http.Server
+	shuttingDown atomic.Bool
+}
+
+// New creates a health check server listening on the given port.
+// Passing port 0 binds to an available ephemeral port.
+func New(port int) (*Server, error) {
+	listener, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", port))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create listener: %w", err)
+	}
+
+	s := &Server{listener: listener}
+	s.server = &http.Server{
+		Handler: http.HandlerFunc(s.handleHealthz),
+	}
+	return s, nil
+}
+
+// Addr returns the bound network address (e.g. "127.0.0.1:8080").
+func (s *Server) Addr() string {
+	if s.listener == nil {
+		return ""
+	}
+	return s.listener.Addr().String()
+}
+
+// Start begins serving HTTP requests. It blocks until Stop is called.
+func (s *Server) Start() error {
+	return s.server.Serve(s.listener)
+}
+
+// Stop initiates graceful shutdown. After Stop is called the /healthz
+// endpoint returns 503 while in-flight requests complete.
+func (s *Server) Stop(ctx context.Context) error {
+	s.shuttingDown.Store(true)
+	// Grace period so that health checks can observe the 503 state
+	// before the listener is closed.
+	time.Sleep(100 * time.Millisecond)
+	return s.server.Shutdown(ctx)
+}
+
+func (s *Server) handleHealthz(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/healthz" {
+		http.NotFound(w, r)
+		return
+	}
+	if s.shuttingDown.Load() {
+		w.WriteHeader(http.StatusServiceUnavailable)
+		return
+	}
+	w.WriteHeader(http.StatusOK)
+}