Wish program with Bubbletea middleware executing a remote command

remote_exec_no_pty.go

package main

import (
	"context"
	"errors"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/log"
	"github.com/charmbracelet/ssh"
	"github.com/charmbracelet/wish"
	bm "github.com/charmbracelet/wish/bubbletea"
	lm "github.com/charmbracelet/wish/logging"
)

func main() {
	s, err := wish.NewServer(
		wish.WithAddress(":23234"),
		wish.WithMiddleware(
			bm.Middleware(teaHandler),
			lm.Middleware(),
		),
	)
	if err != nil {
		log.Error("could not start server", "error", err)
	}

	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	log.Info("Starting SSH server")
	go func() {
		if err = s.ListenAndServe(); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
			log.Error("could not start server", "error", err)
			done <- nil
		}
	}()

	<-done
	log.Info("Stopping SSH server")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer func() { cancel() }()
	if err := s.Shutdown(ctx); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
		log.Error("could not stop server", "error", err)
	}
}

func teaHandler(s ssh.Session) (tea.Model, []tea.ProgramOption) {
	_, _, active := s.Pty()
	if !active {
		wish.Fatalln(s, "no active terminal, skipping")
		return nil, nil
	}
	m := model{s}
	return m, []tea.ProgramOption{
		tea.WithAltScreen(),
	}
}

type model struct {
	session ssh.Session
}

func (m model) Init() tea.Cmd {
	return runCommand(m.session)
}

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	return m, nil
}

func (m model) View() string {
	return ""
}

func runCommand(s ssh.Session) tea.Cmd {
	c := exec.Command("journalctl", "-f")

	return tea.ExecProcess(c, func(err error) tea.Msg {
		if err != nil {
			log.Error(err)
		}
		return tea.Quit()
	})
}

remote_exec_pty.go

package main

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
	"time"
	"unsafe"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/log"
	"github.com/charmbracelet/ssh"
	"github.com/charmbracelet/wish"
	bm "github.com/charmbracelet/wish/bubbletea"
	lm "github.com/charmbracelet/wish/logging"
	"github.com/creack/pty"
)

func main() {
	s, err := wish.NewServer(
		wish.WithAddress(":23234"),
		wish.WithMiddleware(
			bm.Middleware(teaHandler),
			lm.Middleware(),
		),
	)
	if err != nil {
		log.Error("could not start server", "error", err)
	}

	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	log.Info("Starting SSH server")
	go func() {
		if err = s.ListenAndServe(); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
			log.Error("could not start server", "error", err)
			done <- nil
		}
	}()

	<-done
	log.Info("Stopping SSH server")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer func() { cancel() }()
	if err := s.Shutdown(ctx); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
		log.Error("could not stop server", "error", err)
	}
}

func teaHandler(s ssh.Session) (tea.Model, []tea.ProgramOption) {
	_, _, active := s.Pty()
	if !active {
		wish.Fatalln(s, "no active terminal, skipping")
		return nil, nil
	}
	m := model{s}
	return m, []tea.ProgramOption{tea.WithAltScreen()}
}

type model struct {
	session ssh.Session
}

func (m model) Init() tea.Cmd {
	return runCommand(m.session)
}

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	return m, nil
}

func (m model) View() string {
	return ""
}

func runCommand(s ssh.Session) tea.Cmd {
	c := exec.Command("/bin/bash", "-i")
	pty, winChan, _ := s.Pty()
	c.Env = append(c.Env, fmt.Sprintf("TERM=%s", pty.Term))

	return tea.Exec(&execProc{cmd: c, winChan: winChan, pty: pty}, func(err error) tea.Msg {
		if err != nil {
			log.Error(err)
		}
		return tea.Quit()
	})
}

type execProc struct {
	cmd     *exec.Cmd
	winChan <-chan ssh.Window
	stdin   io.Reader
	stdout  io.Writer
	pty     ssh.Pty
}

func (e *execProc) SetStdin(r io.Reader) {
	e.stdin = r
}

func (e *execProc) SetStdout(w io.Writer) {
	e.stdout = w
}

func (e *execProc) SetStderr(w io.Writer) {}

func (e *execProc) Run() error {
	f, err := pty.Start(e.cmd)
	if err != nil {
		return err
	}
	setWinsize(f, e.pty.Window.Width, e.pty.Window.Height)
	go func() {
		for win := range e.winChan {
			setWinsize(f, win.Width, win.Height)
		}
	}()
	go func() {
		io.Copy(f, e.stdin)
	}()
	io.Copy(e.stdout, f)
	return e.cmd.Wait()
}

func setWinsize(f *os.File, w, h int) {
	syscall.Syscall(syscall.SYS_IOCTL, f.Fd(), uintptr(syscall.TIOCSWINSZ),
		uintptr(unsafe.Pointer(&struct{ h, w, x, y uint16 }{uint16(h), uint16(w), 0, 0})))
}