Enable colours when FORCE_COLOR env var is set

What’s the problem this feature will solve?

pip 22 now uses Rich for installation progress bars and some error handling, which gives us pretty colours!

Colour can help diagnose problems, and a common place for pip and the need to diagnose problems is on a CI.

However, because the GitHub Actions isn’t a tty, output of tools which autodetect the terminal output is usually monochrome. That’s why many tools and CI setups use the FORCE_COLOR environment variable, and/or command-line options to turn it back on.

The pip CI included (#10830):

https://github.com/pypa/pip/blob/4a508c268ee4be5bc279f1522954b78fa9e25050/.github/workflows/ci.yml#L14-L17

However, pip itself (and Rich) don’t use FORCE_COLOR, meaning we get monochrome output:

Compare with nox:

https://github.com/pypa/pip/runs/5177210581?check_suite_focus=true

And pytest:

https://github.com/pytest-dev/pytest/runs/5185781927?check_suite_focus=true

Describe the solution you’d like

Enable colour when FORCE_COLOR is set.

For reference:

• pytest issue, PR and docs
• nox issue and PR
• tox PR
• pypa/build PR
• Colorama WIP PR
• Node.js docs

Alternative Solutions

Get Rich to support FORCE_COLOR directly. This was considered in 2020 but rejected in https://github.com/Textualize/rich/issues/343 to leave it up to the developer to support it.

But Will said “I may yet relent on this. I try to be pragmatic!” so it may still be a better option 😃

Additional context

I’m not specifically requesting it here, but could be worth considering also disabling when NO_COLOR is set: https://no-color.org/

Similarly not requesting it here, but for completeness I’ll mention pytest also has this command-line option:

  --color=color         color terminal output (yes/no/auto).

And nox:

  --nocolor, --no-color
                        Disable all color output.
  --forcecolor, --force-color
                        Force color output, even if stdout is not an interactive terminal.

Whereas pip only has the negative:

  --no-color                  Suppress colored output.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[hugovk]

If FORCE_COLOR (any value -> on) has emerged as a standard. I could implement that in Rich.

@willmcgugan This would be great! What’s the next step? Would you like an issue created at https://github.com/Textualize/rich?

[potiuk]

Yeah. That would be indeed very useful. Colors in CI are great for visual communication (as otherwise you end up with big blob of text) - especially that often in Ci you enable pretty verbose output to be able to diagnose problems. Nany tools allows forcing colors indeed so it woud be useful to have it in ‘pip’. Happy to help and create a PR for that one if preferred way to do it is agreed to by the maintainers…