Colorize LogTo output

[ajcvickers]

From an internal discussion with @bricelam: ANSI escape sequences FTW: .LogTo(m => Console.WriteLine("\x1b[1;30m" + m + "\x1b[22;39m"))

A cheatsheet: https://github.com/dotnet/efcore/blob/main/src/ef/AnsiConstants.cs

[roji]

One thing - we should detect whether we're printing to a terminal or not, to avoid outputting ANSI when output is redirected to a pipe or file (e.g. dotnet ef .... > some_file). This is standard Unix behavior which is traditionally done with an isatty check, am hoping that there's something standard for .NET as well...

(is this really about interception?)

[roji]

Maybe this thing?

[bricelam]

IIRC, they added a flag to say whether escape codes are supported (since they weren't until version 1703 of Windows 10). We should use that instead.

[ajcvickers]

@bricelam I think the challenge here is that we don't know where the logs are going. We just send strings to a delegate. So this might have to be a manual opt-in or opt-out.

[roji]

@ajcvickers do you mean it's not possible at the level of dotnet CLI or something? If so that's a serious limitation (is it already tracked?)

[ajcvickers]

I mean just because the application is using a console that supports escape codes doesn't mean that LogTo output is being sent to that console. It might be going to a file, or to an IDE debugging window, or any place else. See examples here: https://docs.microsoft.com/en-us/ef/core/logging-events-diagnostics/simple-logging#directing-the-logs

[roji]

I think that's what Environment.UserInteractive is for. It would be disappointing if .NET didn't have some sort of way to detect this (where Unix had isatty since Roman times).

At some point we should just play around with all these...

[bricelam]

Since we don't know if they'll acutally be using a console, we probably need an opt-in flag. DbContextLoggerOptions.Colorize or someting.