only close plugin server if actually created

Signed-off-by: Nicolas De Loof <[email protected]>

Author: ndeloof

cmd/docker/docker.go

@@ -302,12 +302,12 @@ func tryPluginRun(ctx context.Context, dockerCli command.Cli, cmd *cobra.Command
 	srv, err := socket.NewPluginServer(nil)
 	if err == nil {
 		plugincmd.Env = append(plugincmd.Env, socket.EnvKey+"="+srv.Addr().String())
+		defer func() {
+			// Close the server when plugin execution is over, so that in case
+			// it's still open, any sockets on the filesystem are cleaned up.
+			_ = srv.Close()
+		}()
 	}
-	defer func() {
-		// Close the server when plugin execution is over, so that in case
-		// it's still open, any sockets on the filesystem are cleaned up.
-		_ = srv.Close()
-	}()
 
 	// Set additional environment variables specified by the caller.
 	plugincmd.Env = append(plugincmd.Env, envs...)
@@ -334,7 +334,9 @@ func tryPluginRun(ctx context.Context, dockerCli command.Cli, cmd *cobra.Command
 		//
 		// Repeated invocations will result in EINVAL,
 		// or EBADF; but that is fine for our purposes.
-		_ = srv.Close()
+		if srv != nil {
+			_ = srv.Close()
+		}
 
 		// force the process to terminate if it hasn't already
 		if force {