Readline not enabled for supervisorctl fg <service>?

[knpwrs]

1. When I run a rails app with byebug enabled I am able to enter commands and navigate up and down my byebug command history with the arrow keys.
2. When I run the same rails app under supervisor and then foreground the service (supervisorctl fg rails) I am unable to use the arrow keys as expected. Pressing the up key, for instance, enters ^[[A:

Is there a way to make my arrow keys behave under supervisor as they do when not under supervisor?

[mnaberez]

Is there a way to make my arrow keys behave under supervisor as they do when not under supervisor?

Not with the current implementation:

supervisor/supervisor/supervisorctl.py

Lines 1372 to 1374 in 602d6f5

	# this takes care of the user input
	while True:
	inp = raw_input() + '\n'

[knpwrs]

So it seems like using the arrow keys works when running fg rails from the supervisor shell (launched via supervisorctl -c ./workbench/supervisord.conf), but the arrow keys do not work when going directly to foreground, bypassing the supervisor shell (via supervisorctl -c ./workbench/supervisord.conf fg rails).

This is an example of going to the supervisor shell first and then using fg rails:

Screen.Recording.2022-02-17.at.10.39.31.AM.mov

[knpwrs]

As a workaround it appears that using rlwrap works:

rlwrap supervisorctl -c ./workbench/supervisord.conf fg rails

[mnaberez]

There are two different issues in represented in this ticket. There's the original question:

Is there a way to make my arrow keys behave under supervisor as they do when not under supervisor?

The answer is no because of the implementation. The user input is line buffered by supervisorctl, so the escape sequences for the arrow keys aren't sent to the remote process. They're handled by supervisorctl. This means that programs such as text editors, which expect character input, won't work.

The second issue is this one:

So it seems like using the arrow keys works when running fg rails from the supervisor shell (launched via supervisorctl -c ./workbench/supervisord.conf), but the arrow keys do not work when going directly to foreground, bypassing the supervisor shell (via supervisorctl -c ./workbench/supervisord.conf fg rails).

This would seem to indicate that the local readline (the one used by raw_input in the supervisorctl process) isn't being used for some reason under that invocation.

[knpwrs]

Interesting. rlwrap works for me for now. Thank you!