🌈 slogcolor

slogcolor is a little, customizable color handler for log/slog. It enhances log readability by color-coding log levels and supports flexible formatting options. Its output is inspired by XMRig and zerolog.

Basic Usage

package main

import (
    "os"
    "time"
    "errors"
    "log/slog"

    "github.com/MatusOllah/slogcolor"
)

func main() {
    // Configure slog to use slogcolor by default for colored output
    slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, slogcolor.DefaultOptions)))

    slog.Info("Initializing")
    slog.Debug("Init done", "duration", 500*time.Millisecond)
    slog.Warn("Slow request!", "method", "GET", "path", "/api/users", "duration", 750*time.Millisecond)
    slog.Error("DB connection lost!", "err", errors.New("connection reset"), "db", "horalky")
}

Customized output format

The output format can also be customized using the Options like this:

opts := &slogcolor.Options{
    Level:         slog.LevelDebug,
    TimeFormat:    time.RFC3339,
    SrcFileMode:   slog.Nop,
}
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, opts)))

or like this:

opts := slogcolor.DefaultOptions
opts.Level = slog.LevelDebug
opts.TimeFormat = time.RFC3339
opts.SrcFileMode = slog.Nop

slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, opts)))

Prefixes

Messages can be prefixed with Prefix like this:

slog.Info(slogcolor.Prefix("MyPrefix", "kajšmentke"))
slog.Info(slogcolor.Prefix("SceneController", "switching scene"))

Disable colors

Colors are enabled by default but can be disabled using Options.NoColor. Particularly useful for automatically enabling colors based on the terminal capabilities using e.g. the go-isatty package.

w := os.Stderr

opts := slogcolor.DefaultOptions
opts.NoColor = !isatty.IsTerminal(w.Fd())

slog.SetDefault(slog.New(slogcolor.NewHandler(w, opts)))