Function tryPluginRun

cmd/docker/docker.go:322–441

(ctx context.Context, dockerCli command.Cli, cmd *cobra.Command, subcommand string, envs []string)

}

func tryPluginRun(ctx context.Context, dockerCli command.Cli, cmd *cobra.Command, subcommand string, envs []string) error {
	plugincmd, err := pluginmanager.PluginRunCommand(dockerCli, subcommand, cmd)
	if err != nil {
		return err
	}

	// Establish the plugin socket, adding it to the environment under a
	// well-known key if successful.
	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()
		}()
	}

	// Set additional environment variables specified by the caller.
	plugincmd.Env = append(plugincmd.Env, envs...)

	// Background signal handling logic: block on the signals channel, and
	// notify the plugin via the PluginServer (or signal) as appropriate.
	const exitLimit = 2

	// forceExitCh is closed by the signal goroutine just before it SIGKILLs
	// the plugin. The main goroutine checks this after plugincmd.Run() returns
	// and owns the final os.Exit(1) call, keeping exit-code ownership in one
	// place and avoiding a race between two concurrent os.Exit calls.
	forceExitCh := make(chan struct{})

	tryTerminatePlugin := func(force bool) {
		// If stdin is a TTY, the kernel will forward
		// signals to the subprocess because the shared
		// pgid makes the TTY a controlling terminal.
		//
		// The plugin should have its own copy of this
		// termination logic, and exit after 3 retries
		// on its own.
		if dockerCli.Out().IsTerminal() {
			return
		}

		// Terminate the plugin server, which closes
		// all connections with plugin subprocesses,
		// and signal them to exit.
		//
		// Repeated invocations result in EINVAL or EBADF,
		// but that is fine for our purposes.
		if srv != nil {
			_ = srv.Close()
		}

		// force the process to terminate if it hasn't already
		if force {
			// Close forceExitCh before Kill so the channel is guaranteed
			// to be closed by the time plugincmd.Run() returns: the plugin
			// can only exit after Kill() delivers SIGKILL, and Run() only