Don't terminate when last client leaves about upterm HOT 5 OPEN

Okay, to clarify, I was in a read-only session. So I'd still call this unexpected.

upterm host --read-only zsh

from upterm.

I think I get what is the issue here. It works only when --force-command isn't used. It also works for --read-only sessions.

How to reproduce:

1. Run a host terminal upterm host --read-only in a terminal window.
2. Run a client terminal ssh [email protected] in another terminal window.
3. Terminate (close) the client terminal.
   Expected: The host terminal do nothing dramatic (triggers ClientLeftCallback callback)
   Actual: The host terminal exited with EOF error.

The reason for this behavior is the next few issues:

1. Write and Read-only client terminals affects host terminal dimensions. issue #138
2. When client terminal is terminated, it sends an event with width=0 and height=0 to host terminal. (https://github.com/owenthereal/upterm/blob/master/host/internal/server.go#L253).
3. That cause host terminal to redraw.
4. Redraw triggers a write operation to writers https://github.com/owenthereal/upterm/blob/master/host/internal/command.go#L127. It has 3 writers at this point (MultiWriter internal cache, host terminal stdout, remote session).
5. Because remote session is already terminated that causes EOF error.

Possible ways to fix:

1. Don't redraw the host terminal when the client terminal gets killed.
2. Check session.Context().Done() somewhere (e.g. https://github.com/owenthereal/upterm/blob/master/host/internal/server.go#L195 ) that would trigger a dead writer to be removed here https://github.com/owenthereal/upterm/blob/master/host/internal/server.go#L242
3. Handle writes to clients differently and ignore if they're broken/unstable. I believe that might also fix #134 but I didn't investigate that case.

from upterm.

@mweinelt:

What command did you run? For example, if you run bash (e.g., upterm host -- bash) and the client types exit, the exit is sent to the bash command, and it will exit the bash process on the host. If you want that quitting client doesn't exit your host's running process, you would need a terminal multiplexer like tmux. tmux runs a server on the host, and quitting clients won't exit the tmux server on the host. For example, the following creates a tmux session on the host and forces clients to join by attaching to the tmux server: upterm host --force-command 'tmux attach -t pair-programming' -- tmux new -t pair-programming (Ref: https://github.com/owenthereal/upterm#quick-reference)

from upterm.

Right, i was running just plain zsh. Somewhat unexpected but understandable.

from upterm.

This seems to not only happen when the last client leaves.

We can reproducibly bring upterm to terminate when any client of a read-only session closes (either with the SSH sequence [enter] ~ ., or by closing the terminal window).

from upterm.