NO_COLOR support

[msalib]

I love color-eyre when developing locally; it is so incredibly helpful! But the colors are a problem when deploying to prod where, for example, Cloudwatch logs for AWS Lambda functions just include raw ANSI escape sequences. I'm working around that right now by using this code in my setup function:

        if std::env::var("NO_COLOR") == Err(std::env::VarError::NotPresent) {
            color_eyre::install()?;
        } else {
            color_eyre::config::HookBuilder::new()
                .theme(color_eyre::config::Theme::new())
                .install()?;
        }

and making sure our prod deployments include NO_COLOR=1.

I'd love to see either:

• a mention of this particular pattern in the docs (I searched and couldn't find anything), or
• a change to HookBuilder::blank() selecting either the default dark theme or the blank theme based on the presence of NO_COLOR

I'm sure you've already seen this, but I found https://no-color.org/ helpful

I'm sorry I don't have the time right now to write up a draft PR for you.

[yaahc]

Glad to hear you're enjoying color-eyre 😊.

a mention of this particular pattern in the docs (I searched and couldn't find anything)

Happy to add this. Do you remember where you searched for this first? I figure those will be the best places to put the example to make sure ppl find it in the future.

a change to HookBuilder::blank() selecting either the default dark theme or the blank theme based on the presence of NO_COLOR

Also happy with doing this, I think I have a preference for the former suggestion but I don't mind this one or even doing both.

I'm sure you've already seen this, but I found https://no-color.org/ helpful

I hadn't seen this! I think this would be a good link to include in any updated examples we end up adding for this.

I'm sorry I don't have the time right now to write up a draft PR for you.

No worries! Thank you for taking the time to submit the issue.

[pksunkara]

There was quite a bit of work done on colorchoice crate as part of https://github.com/rust-cli/anstyle that handles the "should we color?" question. cc @epage

[epage]

colorchoice is just about having a central global so CLI control doesn't need to be piped through the entire program.

For NO_COLOR, that would normally be handled via printing via anstream which has you write your colors and then strips them depending on the environment the program is running within