enforce ordering of libbeat API server Start/Stop functions

libbeat/api/server.go

@@ -33,13 +33,15 @@ import (
 // Server takes care of correctly starting the HTTP component of the API
 // and will answer all the routes defined in the received ServeMux.
 type Server struct {
-	log        *logp.Logger
-	mux        *http.ServeMux
-	l          net.Listener
-	config     Config
-	wg         sync.WaitGroup
-	mutex      sync.Mutex
-	httpServer *http.Server
+	log         *logp.Logger
+	mux         *http.ServeMux
+	l           net.Listener
+	config      Config
+	wg          sync.WaitGroup
+	mutex       sync.Mutex
+	httpServer  *http.Server
+	startCalled bool
+	stopCalled  bool
 }
 
 // New creates a new API Server with no routes attached.
@@ -67,6 +69,17 @@ func New(log *logp.Logger, config *config.C) (*Server, error) {
 func (s *Server) Start() {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
+
+	// only need to call Start once
+	if s.startCalled {
+		return
+	}
+	s.startCalled = true
+
+	if s.stopCalled {
+		s.log.Info("Not starting stating stats endpoint since stop was already called")
+		return
+	}
 	s.log.Info("Starting stats endpoint")
 	s.wg.Add(1)
 	s.httpServer = &http.Server{Handler: s.mux} //nolint:gosec // Keep original behavior
@@ -83,12 +96,23 @@ func (s *Server) Start() {
 func (s *Server) Stop() error {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
+	// only need to call Stop once
+	if s.stopCalled {
+		return nil
+	}
+	s.stopCalled = true
+
 	if s.httpServer == nil {
+		// New always creates a listener, need to close it even if the server hasn't started
+		if err := s.l.Close(); err != nil {
+			s.log.Infof("Error closing stats endpoint (%s): %v", s.l.Addr().String(), err)
+		}
 		return nil
 	}
 	if err := s.httpServer.Close(); err != nil {
 		return fmt.Errorf("error closing monitoring server: %w", err)
 	}
+
 	s.wg.Wait()
 	return nil
 }

libbeat/api/server_test.go

@@ -19,16 +19,20 @@ package api
 
 import (
 	"context"
+	"encoding/base64"
 	"io"
+	"math/rand/v2"
 	"net"
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"path/filepath"
 	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/goleak"
 
 	"github.com/elastic/elastic-agent-libs/config"
 	"github.com/elastic/elastic-agent-libs/logp/logptest"
@@ -41,7 +45,7 @@ func TestConfiguration(t *testing.T) {
 		return
 	}
 	t.Run("when user is set", func(t *testing.T) {
-		cfg := config.MustNewConfigFrom(map[string]interface{}{
+		cfg := config.MustNewConfigFrom(map[string]any{
 			"host": "unix:///tmp/ok",
 			"user": "admin",
 		})
@@ -51,7 +55,7 @@ func TestConfiguration(t *testing.T) {
 	})
 
 	t.Run("when security descriptor is set", func(t *testing.T) {
-		cfg := config.MustNewConfigFrom(map[string]interface{}{
+		cfg := config.MustNewConfigFrom(map[string]any{
 			"host":                "unix:///tmp/ok",
 			"security_descriptor": "D:P(A;;GA;;;1234)",
 		})
@@ -87,7 +91,7 @@ func TestSocket(t *testing.T) {
 		sockFile := tmpDir + "/test.sock"
 		t.Log(sockFile)
 
-		cfg := config.MustNewConfigFrom(map[string]interface{}{
+		cfg := config.MustNewConfigFrom(map[string]any{
 			"host": "unix://" + sockFile,
 		})
 
@@ -130,7 +134,7 @@ func TestSocket(t *testing.T) {
 		require.NoError(t, err)
 		f.Close()
 
-		cfg := config.MustNewConfigFrom(map[string]interface{}{
+		cfg := config.MustNewConfigFrom(map[string]any{
 			"host": "unix://" + sockFile,
 		})
 
@@ -167,7 +171,7 @@ func TestHTTP(t *testing.T) {
 	// select a random free port.
 	url := "http://localhost:0"
 
-	cfg := config.MustNewConfigFrom(map[string]interface{}{
+	cfg := config.MustNewConfigFrom(map[string]any{
 		"host": url,
 	})
 	logger := logptest.NewTestingLogger(t, "")
@@ -198,7 +202,7 @@ func attachEchoHelloHandler(t *testing.T, s *Server) {
 }
 
 func TestAttachHandler(t *testing.T) {
-	cfg := config.MustNewConfigFrom(map[string]interface{}{
+	cfg := config.MustNewConfigFrom(map[string]any{
 		"host": "http://localhost:0",
 	})
 
@@ -222,8 +226,84 @@ func TestAttachHandler(t *testing.T) {
 	assert.Equal(t, http.StatusMovedPermanently, resp.Result().StatusCode)
 }
 
+func TestOrdering(t *testing.T) {
+	monitorSocket := genSocketPath()
+	var monitorHost string
+	if runtime.GOOS == "windows" {
+		monitorHost = "npipe:///" + filepath.Base(monitorSocket)
+	} else {
+		monitorHost = "unix://" + monitorSocket
+	}
+	cfg := config.MustNewConfigFrom(map[string]any{
+		"host": monitorHost,
+	})
+
+	t.Run("NewStartStop", func(t *testing.T) {
+		defer goleak.VerifyNone(t)
+		logger := logptest.NewTestingLogger(t, "")
+		s, err := New(logger, cfg)
+		require.NoError(t, err)
+		s.Start()
+		err = s.Stop()
+		require.NoError(t, err)
+		s.wg.Wait()
+	})
+	t.Run("NewStopStart", func(t *testing.T) {
+		defer goleak.VerifyNone(t)
+		logger := logptest.NewTestingLogger(t, "")
+		s, err := New(logger, cfg)
+		require.NoError(t, err)
+		err = s.Stop()
+		require.NoError(t, err)
+		s.Start()
+		s.wg.Wait()
+	})
+	t.Run("NewStop", func(t *testing.T) {
+		defer goleak.VerifyNone(t)
+		logger := logptest.NewTestingLogger(t, "")
+		s, err := New(logger, cfg)
+		require.NoError(t, err)
+		err = s.Stop()
+		require.NoError(t, err)
+		s.wg.Wait()
+	})
+	t.Run("NewStopStop", func(t *testing.T) {
+		defer goleak.VerifyNone(t)
+		logger := logptest.NewTestingLogger(t, "")
+		s, err := New(logger, cfg)
+		require.NoError(t, err)
+		err = s.Stop()
+		require.NoError(t, err)
+		err = s.Stop()
+		require.NoError(t, err)
+		s.wg.Wait()
+	})
+	t.Run("NewStartStartStop", func(t *testing.T) {
+		defer goleak.VerifyNone(t)
+		logger := logptest.NewTestingLogger(t, "")
+		s, err := New(logger, cfg)
+		require.NoError(t, err)
+		s.Start()
+		s.Start()
+		err = s.Stop()
+		require.NoError(t, err)
+		s.wg.Wait()
+	})
+}
+
 func newTestHandler(response string) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		_, _ = io.WriteString(w, response)
 	})
 }
+
+func genSocketPath() string {
+	randData := make([]byte, 16)
+	for i := range len(randData) {
+		randData[i] = uint8(rand.UintN(255)) //nolint:gosec // 0-255 fits in a uint8
+	}
+	socketName := base64.URLEncoding.EncodeToString(randData) + ".sock"
+	// don't use t.TempDir() because it can be too long
+	socketDir := os.TempDir()
+	return filepath.Join(socketDir, socketName)
+}