Package tint implements a zero-dependency slog.Handler
that writes tinted (colorized) logs. Its output format is inspired by the zerolog.ConsoleWriter and
slog.TextHandler.
The output format can be customized using Options
which is a drop-in replacement for slog.HandlerOptions.
go get github.com/lmittmann/tint
w := os.Stderr
// Create a new logger
logger := slog.New(tint.NewHandler(w, nil))
// Set global logger with custom options
slog.SetDefault(slog.New(
tint.NewHandler(w, &tint.Options{
Level: slog.LevelDebug,
TimeFormat: time.Kitchen,
}),
))ReplaceAttr can be used to alter or drop attributes. If set, it is called on
each non-group attribute before it is logged. See slog.HandlerOptions
for details.
// Create a new logger with a custom TRACE level:
const LevelTrace = slog.LevelDebug - 4
w := os.Stderr
logger := slog.New(tint.NewHandler(w, &tint.Options{
Level: LevelTrace,
ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
if a.Key == slog.LevelKey && len(groups) == 0 {
level, ok := a.Value.Any().(slog.Level)
if ok && level <= LevelTrace {
return tint.Attr(13, slog.String(a.Key, "TRC"))
}
}
return a
},
}))// Create a new logger that doesn't write the time
w := os.Stderr
logger := slog.New(
tint.NewHandler(w, &tint.Options{
ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
if a.Key == slog.TimeKey && len(groups) == 0 {
return slog.Attr{}
}
return a
},
}),
)// Create a new logger that writes all errors in red
w := os.Stderr
logger := slog.New(
tint.NewHandler(w, &tint.Options{
ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
if a.Value.Kind() == slog.KindAny {
if _, ok := a.Value.Any().(error); ok {
return tint.Attr(9, a)
}
}
return a
},
}),
)Colors are enabled by default. Use the Options.NoColor field to disable
color output. To automatically enable colors based on terminal capabilities, use
e.g., the go-isatty package:
w := os.Stderr
logger := slog.New(
tint.NewHandler(w, &tint.Options{
NoColor: !isatty.IsTerminal(w.Fd()),
}),
)Color support on Windows can be added by using e.g., the
go-colorable package:
w := os.Stderr
logger := slog.New(
tint.NewHandler(colorable.NewColorable(w), nil),
)