Hide stack traces unless debug mode is enabled.

[danielhollas]

I always find it jarring when as a user a python CLI tool spews a full stack trace into my terminal. More importantly, I always have to squint to find tha actual error.

I wonder whether it wouldn't be a more user friendly to disable stack traces unless a debug mode is enabled? Something.like below perhaps?
https://stackoverflow.com/a/27674608

I am asking both as a user of this specific package, but also in general as a newbie Python dev about what's the best practice here.

[csadorf]

I agree, there should ideally never be a traceback visible to the user which is why all expected exceptions should be caught and handled in https://github.com/aiidalab/aiidalab-launch/blob/main/aiidalab_launch/__main__.py .

However, it is of course possible that something "falls through the cracks", and setting the tracebacklimit to 0 could be a viable solution to address that. But I assume that the error message would potentially be even more cryptic, the traceback dump at least indicates that something went "horribly wrong". Using a custom sys.excepthook exception handler might be a better option, where we can at least show a message that explains that the program crashed with an unexpected error.

Maybe it would be worthwhile to find an example of such an implementation in a "popular" CLI application that we could compare against?

Did you encounter a traceback with the package or is this just a general question?

[danielhollas]

Here's an example of what happens when you provide an non-existent profile name.

$ aiidalab-launch profiles edit invalid
Traceback (most recent call last):
  File "/home/bl22441/.local/bin/aiidalab-launch", line 8, in <module>
    sys.exit(cli())
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 1128, in __call__
    return self.main(*args, **kwargs)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/decorators.py", line 84, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/aiidalab_launch/__main__.py", line 245, in edit_profile
    current_profile = app_state.config.get_profile(profile)
  File "/home/bl22441/.local/pipx/venvs/aiidalab_launch/lib/python3.8/site-packages/aiidalab_launch/config.py", line 65, in get_profile
    raise ValueError(f"Did not find profile with name '{name}'.")
ValueError: Did not find profile with name 'invalid'.

It would be great if only the last line was printed, or if we need more context to limit the traceback depth to 1 for example.

Also all the additional validations that we added for extra mounts throw ValueError which I think is not handled in __main__.py

[csadorf]

@danielhollas Would you be open to trying to implement this?

[danielhollas]

@csadorf sure, I can give it a shot, feel free to assign this to me. Although it's a low priority for now so if somebody else wants to go ahead feel free.