`colorama` disables colors in GitHub Actions

[abitrolly]

GitHub Actions provide no TTY, so colorama import wraps stdout and strips all colors https://github.com/tartley/colorama/issues/209#issuecomment-465119302 so even forcing colors doesn't work.

2022-06-30T17:00:45.4633499Z Successfully installed build-0.8.0 pep517-0.12.0 tomli-2.0.1
2022-06-30T17:00:46.1506025Z ##[group]Run python -m build
2022-06-30T17:00:46.1506287Z [36;1mpython -m build[0m
2022-06-30T17:00:46.1506499Z [36;1mgit status --ignored[0m
2022-06-30T17:00:46.1559508Z shell: /usr/bin/bash -e {0}
2022-06-30T17:00:46.1559700Z env:
2022-06-30T17:00:46.1559871Z   FORCE_COLOR: 1
2022-06-30T17:00:46.1560056Z ##[endgroup]
2022-06-30T17:00:46.6361795Z * Creating venv isolated environment...
2022-06-30T17:00:49.6232262Z * Installing packages in isolated environment... (setuptools >= 40.8.0, wheel)
2022-06-30T17:00:52.0028343Z * Getting dependencies for sdist...

Took me a while to debug this. Added some debug statements.

--- a/src/build/__main__.py
+++ b/src/build/__main__.py
@@ -49,6 +49,7 @@ def _init_colors() -> Dict[str, str]:
 _STYLES = _init_colors()
 print(_STYLES)
 
+print('{red}ERROR{reset} {}'.format("msg", **_STYLES))
 
 def _showwarning(
     message: Union[Warning, str],
@@ -65,6 +64,7 @@ def _showwarning(
 
 
 def _setup_cli() -> None:
+    print('{red}ERROR{reset} {}'.format("precolorama", **_STYLES))
     warnings.showwarning = _showwarning
 
     try:
@@ -73,6 +73,7 @@ def _setup_cli() -> None:
         pass
     else:
         colorama.init()  # fix colors on windows
+    print('{red}ERROR{reset} {}'.format("postcolorama", **_STYLES))
 
 
 def _error(msg: str, code: int = 1) -> NoReturn:  # pragma: no cover

And got this.

The solution is to enable colorama only on Windows.

[henryiii]

That seems pretty reasonable to do, but just curious, why is colorama even present? It should not be installed on linux/macOS generally.

[abitrolly]

colorama is needed on Windows, because its terminal is unable to render ANSI sequences by itself. Why it was installed in Linux needs further investigation.

[abitrolly]

colorama is present by default on ubuntu-latest GHA runners.

https://github.com/yakshaveinc/python/runs/7144602632?check_suite_focus=true

But I haven't found why it is here. Software list doesn't include it https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2204-Readme.md and I couldn't find build logs for runner images to trace down who installs it. pip also doesn't seem to include the feature to track who needed a dependency.

[abitrolly]

Asked why the deps here https://github.com/actions/virtual-environments/issues/5851