func (o Options) ExecuteProcess() (int, error) {
	if o.ArtifactDir != "" {
		if err := os.MkdirAll(o.ArtifactDir, os.ModePerm); err != nil {
			return InternalErrorCode, fmt.Errorf("could not create artifact directory(%s): %v", o.ArtifactDir, err)
		}
	}
	processLogFile, err := os.Create(o.ProcessLog)
	if err != nil {
		return InternalErrorCode, fmt.Errorf("could not create process logfile(%s): %v", o.ProcessLog, err)
	}
	defer processLogFile.Close()

	output := io.MultiWriter(os.Stdout, processLogFile)
	logrus.SetOutput(output)
	defer logrus.SetOutput(os.Stdout)

	// if we get asked to terminate we need to forward
	// that to the wrapped process as if it timed out
	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)

	if o.PreviousMarker != "" {
		ctx, cancel := context.WithCancel(context.Background())
		go func() {
			select {
			case s := <-interrupt:
				logrus.Errorf("Received interrupt %s, cancelling...", s)
				cancel()
			case <-ctx.Done():
			}
		}()
		code, err := wrapper.WaitForMarker(ctx, o.PreviousMarker)
		cancel() // end previous go-routine when not interrupted
		if err != nil {
			return InternalErrorCode, fmt.Errorf("wait for previous marker %s: %v", o.PreviousMarker, err)
		}
		if code != 0 {
			logrus.Infof("Skipping as previous step exited %d", code)
			return PreviousErrorCode, nil
		}
	}

	executable := o.Args[0]
	var arguments []string
	if len(o.Args) > 1 {
		arguments = o.Args[1:]
	}
	command := exec.Command(executable, arguments...)
	command.Stderr = output
	command.Stdout = output
	if err := command.Start(); err != nil {
		return InternalErrorCode, fmt.Errorf("could not start the process: %v", err)
	}

	timeout := optionOrDefault(o.Timeout, DefaultTimeout)
	gracePeriod := optionOrDefault(o.GracePeriod, DefaultGracePeriod)
	var commandErr error
	cancelled, aborted := false, false
	done := make(chan error)
	go func() {
		done <- command.Wait()
	}()
	select {
	case err := <-done:
		commandErr = err
	case <-time.After(timeout):
		logrus.Errorf("Process did not finish before %s timeout", timeout)
		cancelled = true
		gracefullyTerminate(command, done, gracePeriod)
	case s := <-interrupt:
		logrus.Errorf("Entrypoint received interrupt: %v", s)
		cancelled = true
		aborted = true
		gracefullyTerminate(command, done, gracePeriod)
	}

	var returnCode int
	if cancelled {
		if aborted {
			commandErr = errAborted
			returnCode = AbortedErrorCode
		} else {
			commandErr = errTimedOut
			returnCode = InternalErrorCode
		}
	} else {
		if status, ok := command.ProcessState.Sys().(syscall.WaitStatus); ok {
			returnCode = status.ExitStatus()
		} else if commandErr == nil {
			returnCode = 0
		} else {
			returnCode = 1
		}

		if returnCode != 0 {
			commandErr = fmt.Errorf("wrapped process failed: %v", commandErr)
		}
	}
	return returnCode, commandErr
}
func (o Options) ExecuteProcess() (int, error) {
	if o.ArtifactDir != "" {
		if err := os.MkdirAll(o.ArtifactDir, os.ModePerm); err != nil {
			return InternalErrorCode, fmt.Errorf("could not create artifact directory(%s): %v", o.ArtifactDir, err)
		}
	}
	processLogFile, err := os.Create(o.ProcessLog)
	if err != nil {
		return InternalErrorCode, fmt.Errorf("could not create process logfile(%s): %v", o.ProcessLog, err)
	}
	defer processLogFile.Close()

	output := io.MultiWriter(os.Stdout, processLogFile)
	logrus.SetOutput(output)
	defer logrus.SetOutput(os.Stdout)

	// if we get asked to terminate we need to forward
	// that to the wrapped process as if it timed out
	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)

	if o.PreviousMarker != "" {
		ctx, cancel := context.WithCancel(context.Background())
		go func() {
			select {
			case s := <-interrupt:
				logrus.Errorf("Received interrupt %s, cancelling...", s)
				cancel()
			case <-ctx.Done():
			}
		}()
		code, err := wrapper.WaitForMarker(ctx, o.PreviousMarker)
		cancel() // end previous go-routine when not interrupted
		if err != nil {
			return InternalErrorCode, fmt.Errorf("wait for previous marker %s: %v", o.PreviousMarker, err)
		}
		if code != 0 {
			logrus.Infof("Skipping as previous step exited %d", code)
			return PreviousErrorCode, nil
		}
	}

	executable := o.Args[0]
	var arguments []string
	if len(o.Args) > 1 {
		arguments = o.Args[1:]
	}
	command := exec.Command(executable, arguments...)
	command.Stderr = output
	command.Stdout = output
	if err := command.Start(); err != nil {
		return InternalErrorCode, fmt.Errorf("could not start the process: %v", err)
	}

	timeout := optionOrDefault(o.Timeout, DefaultTimeout)
	gracePeriod := optionOrDefault(o.GracePeriod, DefaultGracePeriod)
	var commandErr error
	cancelled, aborted := false, false
	done := make(chan error)
	go func() {
		done <- command.Wait()
	}()
	select {
	case err := <-done:
		commandErr = err
	case <-time.After(timeout):
		logrus.Errorf("Process did not finish before %s timeout", timeout)
		cancelled = true
		gracefullyTerminate(command, done, gracePeriod)
	case s := <-interrupt:
		logrus.Errorf("Entrypoint received interrupt: %v", s)
		cancelled = true
		aborted = true
		gracefullyTerminate(command, done, gracePeriod)
	}

	var returnCode int
	if cancelled {
		if aborted {
			commandErr = errAborted
			returnCode = AbortedErrorCode
		} else {
			commandErr = errTimedOut
			returnCode = InternalErrorCode
		}
	} else {
		if status, ok := command.ProcessState.Sys().(syscall.WaitStatus); ok {
			returnCode = status.ExitStatus()
		} else if commandErr == nil {
			returnCode = 0
		} else {
			returnCode = 1
		}

		if returnCode != 0 {
			commandErr = fmt.Errorf("wrapped process failed: %v", commandErr)
		}
	}
	return returnCode, commandErr
}
// ExecuteProcess creates the artifact directory then executes the process as
// configured, writing the output to the process log.