fix: remove the socket if it already exists

Signed-off-by: GitHub <[email protected]>

Author: isaac-dasan

cns/deviceplugin/server.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"os"
 	"time"
 
 	"github.com/pkg/errors"
@@ -45,6 +46,11 @@ func (s *Server) Run(ctx context.Context) error {
 	defer cancel()
 	s.shutdownCh = childCtx.Done()
 
+	// remove the socket if it already exists
+	if err := os.Remove(s.address); err != nil && !os.IsNotExist(err) {
+		return errors.Wrap(err, "error removing socket")
+	}
+
 	l, err := net.Listen("unix", s.address)
 	if err != nil {
 		return errors.Wrap(err, "error listening on socket")

cns/deviceplugin/server_test.go

@@ -0,0 +1,69 @@
+package deviceplugin
+
+import (
+	"context"
+	"net"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+type mockDeviceCounter struct {
+	count int
+}
+
+func (m *mockDeviceCounter) getDeviceCount() int {
+	return m.count
+}
+
+func TestServer_Run_CleansUpExistingSocket(t *testing.T) {
+	// Create a temporary directory for the socket
+	tmpDir := t.TempDir()
+	socketPath := filepath.Join(tmpDir, "test.sock")
+
+	// Create a dummy file at the socket path to simulate a stale socket
+	if err := os.WriteFile(socketPath, []byte("stale socket"), 0644); err != nil {
+		t.Fatalf("failed to create dummy socket file: %v", err)
+	}
+
+	logger := zap.NewNop()
+	counter := &mockDeviceCounter{count: 1}
+	server := NewServer(logger, socketPath, counter, time.Second)
+
+	// Create a context that we can cancel to stop the server
+	ctx, cancel := context.WithCancel(context.Background())
+
+	// Run the server in a goroutine
+	errChan := make(chan error)
+	go func() {
+		errChan <- server.Run(ctx)
+	}()
+
+	// Wait for the server to start up, delete the pre-existing file and recreate it as a socket
+	// We verify this by trying to connect to the socket repeatedly until success or timeout
+	var conn net.Conn
+	var err error
+	// Retry for up to 2 seconds
+	for start := time.Now(); time.Since(start) < 2*time.Second; time.Sleep(200 * time.Millisecond) {
+		conn, err = net.Dial("unix", socketPath)
+		if err == nil {
+			conn.Close()
+			break
+		}
+	}
+
+	if err != nil {
+		t.Errorf("failed to connect to socket: %v", err)
+	}
+
+	// Stop the server
+	cancel()
+
+	// Wait for Run to return
+	if err := <-errChan; err != nil {
+		t.Errorf("server.Run returned error: %v", err)
+	}
+}