gologger

gologger is a very simple logging package to do structured logging in go.

Features

• Simple and fast structured logging with beautiful CLI output
• Fully compatible with Go's standard log/slog package
• Zero-breaking-change migration - use both APIs simultaneously
• Identical output format - slog calls produce same CLI appearance
• Rich metadata support - structured key-value logging
• Multiple levels - Info, Debug, Warning, Error, Fatal, Verbose, Silent
• Custom formatters - CLI, JSON, and custom formats
• Flexible writers - stdout/stderr, files, rotation, custom writers

Use gologger as a library

package main

import (
	"strconv"

	"github.com/projectdiscovery/gologger"
	"github.com/projectdiscovery/gologger/levels"
)

func main() {
	gologger.DefaultLogger.SetMaxLevel(levels.LevelDebug)
	//	gologger.DefaultLogger.SetFormatter(&formatter.JSON{})
	gologger.Print().Msgf("\tgologger: sample test\t\n")
	gologger.Info().Str("user", "pdteam").Msg("running simulation program")
	for i := 0; i < 10; i++ {
		gologger.Info().Str("count", strconv.Itoa(i)).Msg("running simulation step...")
	}
	gologger.Debug().Str("state", "running").Msg("planner running")
	gologger.Warning().Str("state", "errored").Str("status", "404").Msg("could not run")
	gologger.Fatal().Msg("bye bye")
}

slog Compatibility

gologger is fully compatible with Go's standard log/slog package. You can use gologger as an slog handler to get the same beautiful CLI output while leveraging the standard Go logging ecosystem.

Quick Start with slog

package main

import (
	"log/slog"
	"github.com/projectdiscovery/gologger"
	"github.com/projectdiscovery/gologger/levels"
)

func main() {
	// Setup gologger as slog handler (one-time setup)
	gologger.DefaultLogger.SetMaxLevel(levels.LevelVerbose)
	slog.SetDefault(slog.New(gologger.DefaultLogger))
	
	// Now both APIs produce identical output:
	gologger.Info().Str("user", "john").Msg("Hello from gologger") 
	slog.Info("Hello from slog", slog.String("user", "john"))
	
	// Both output: [INF] Hello from gologger [user=john]
	//              [INF] Hello from slog [user=john]
}

Migration Benefits

• 🔄 Zero Breaking Changes: All existing gologger code continues working
• 🎯 Identical Output: slog produces the exact same CLI format
• 📈 Incremental Migration: Migrate function by function at your own pace
• 🌟 Best of Both Worlds: Keep gologger's aesthetics, gain slog's ecosystem
• 🔧 Advanced Features: Groups, persistent attributes, different handler types

Learn More

See the complete slog Compatibility Guide for:

• Detailed side-by-side API comparisons with output examples
• How attributes, groups, and custom levels work
• Step-by-step migration strategies
• Advanced features and best practices

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gologger is made with 🖤 by the projectdiscovery team.