should `NO_COLOR=` disable color output?

[spacedub]

Right now, if NO_COLOR="", output colors will be disabled.
eg: colors are enabled only if NO_COLOR is not set at all.

Comment in the source here https://github.com/moby/buildkit/blob/master/util/progress/progressui/init.go#L18
suggests that this is on purpose, but this seems to differ from the example at https://no-color.org/ right?

[jedevc]

Ah nice find 🎉 Yeah this looks like an unintentional bug to me, the comment seems to refer to how BuildKit writes colors from the global variables.

Quoting from the site (emphasis mine):

Command-line software which adds ANSI color to its output by default should check for a NO_COLOR environment variable that, when present and not an empty string (regardless of its value), prevents the addition of ANSI color.

[spkane]

I was curious about what I was thinking at the time I made the original PR for the buildkit color functionality, and I noticed that the NO_COLOR folks changed the wording about this right as I was working on this.

jcs/no_color@99f90e2

So, that explains the shift. I simply misinterpreted what they meant and they have clarified it since then.