Option isatty=True not always working

[pascal-hari]

Detected issue

When passing the parameter isatty=True to the method coloredlogs.install() the logger does not always generate a colored output.

Conditions

I use this option because I run on windows and use a git bash terminal. Since git bash is using pipes it's not detecting the terminal correctly with sys.stdout.isatty().

Expected behavior

I would expect with the isatty=True to the method coloredlogs.install() that the colored output is forced independent of sys.stdout.isatty().

Version

This has been discovered when running on version 14.0.

More information on issue

Debugging the module has shown that the method terminal_supports_colors(stream) returns false and the use_colors gets deactivated. More debugging has shown that in there the sys.stdout.isatty() is called.
Looking at those lines there is no difference from 'isatty'=None and 'isatty'=True.

Possible fix

For me changing line 433 to if use_colors is None: solved the issue. But I cannot tell if this is a valid fix, since I do not know other use cases.

[dwardzinski-jsf]

I am also having this issue. Looking at the source code, it would appear that only isatty=False has any effect (forces colors to be disabled). As you mentioned, isatty=True and isatty=None both use terminal auto-detection, so setting isatty=True makes no difference. Your fix (changing line 433 to if use_color is None:) would appear to be a valid fix, since it does make sense for isatty=True to force coloring regardless of whether the script thinks it's in an interactive terminal or not.

As for use cases, I've personally been having some issues with this since I'm calling my script through a job scheduler like cron (which disables coloring since it's not being called through a terminal). I've managed to find a workaround without changing the source code by making the scheduler call script -q -c 'python3 script.py' instead, which tricks it into thinking it's being called through a terminal. However, that also ended up causing other issues like SIGTERM signals not being intercepted properly (which is being used in my script). So, changing the source code looks like the way to go until this is fixed.

[heni]

use could install my version locally, just executing command
pip install -U git+https://github.com/heni/python-coloredlogs.git@fix/isatty-force-attribute

[michael-o]

I basically have the same problem, but with a different usecase. My Python code runs a shared GitLab runner and I do pass isatty=True and expected that colors are forced even if we are not attached to a terminal, but still autodetection works. I'd expect that True would force/override detection.

[michael-o]

@heni Your patch works for me in the GitLab runner.

[xolox]

Hi all and thanks for the feedback. I've just published coloredlogs release 14.1 which fixes this issue.