README
¶
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/slogpackage - 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
gologger is made with 🖤 by the projectdiscovery team.
Documentation
¶
Overview ¶
Package gologger provides a simple layer for leveled logging in go.
Index ¶
- Constants
- func TrimGologgerLevels() *slog.HandlerOptions
- type Event
- type Logger
- func (l *Logger) Debug() *Event
- func (l *Logger) Enabled(_ context.Context, level slog.Level) bool
- func (l *Logger) Error() *Event
- func (l *Logger) Fatal() *Event
- func (l *Logger) Handle(ctx context.Context, record slog.Record) error
- func (l *Logger) Info() *Event
- func (l *Logger) Log(event *Event)
- func (l *Logger) Print() *Event
- func (l *Logger) SetFormatter(formatter formatter.Formatter)
- func (l *Logger) SetMaxLevel(level levels.Level)
- func (l *Logger) SetTimestamp(timestamp bool, minLevel levels.Level)
- func (l *Logger) SetTimestampWithFormat(timestamp bool, minLevel levels.Level, format string)
- func (l *Logger) SetWriter(writer writer.Writer)
- func (l *Logger) Verbose() *Event
- func (l *Logger) Warning() *Event
- func (l *Logger) WithAttrs(attrs []slog.Attr) slog.Handler
- func (l *Logger) WithGroup(name string) slog.Handler
Constants ¶
const ( LevelTrace = slog.Level(-8) // Most detailed logging (DEBUG-4) LevelVerbose = slog.Level(-6) // More detailed than debug (DEBUG-2) LevelSilent = slog.Level(1) // No label output (INFO+1) LevelFatal = slog.Level(12) // Critical errors causing exit (ERROR+4) )
Custom slog levels that match gologger's level hierarchy. These can be used with any slog handler.
Variables ¶
This section is empty.
Functions ¶
func TrimGologgerLevels ¶ added in v1.1.69
func TrimGologgerLevels() *slog.HandlerOptions
TrimGologgerLevels creates handler options that convert gologger offset levels to clean names e.g., "DEBUG-4" becomes "TRACE", "ERROR+4" becomes "FATAL", "INFO+1" becomes "" (silent)
Types ¶
type Event ¶ added in v1.1.0
type Event struct {
// contains filtered or unexported fields
}
Event is a log event to be written with data
func Warning ¶
func Warning() *Event
Warning writes a warning message on the screen with the default label
func (*Event) MsgFunc ¶ added in v1.1.5
MsgFunc logs a message with lazy evaluation. Useful when computing the message can be resource heavy.
type Logger ¶ added in v1.1.0
type Logger struct {
// contains filtered or unexported fields
}
Logger is a logger for logging structured data in a beautiful and fast manner.
var ( // DefaultLogger is the default logging instance DefaultLogger *Logger )
func (*Logger) Debug ¶ added in v1.1.0
Debug writes an error message on the screen with the default label
func (*Logger) Error ¶ added in v1.1.0
Error writes a error message on the screen with the default label
func (*Logger) Info ¶ added in v1.1.0
Info writes a info message on the screen with the default label
func (*Logger) SetFormatter ¶ added in v1.1.0
SetFormatter sets the formatter instance for a logger
func (*Logger) SetMaxLevel ¶ added in v1.1.0
SetMaxLevel sets the max logging level for logger
func (*Logger) SetTimestamp ¶ added in v1.1.6
SetTimestamp enables/disables automatic or custom timestamp
func (*Logger) SetTimestampWithFormat ¶ added in v1.1.58
func (*Logger) Warning ¶ added in v1.1.0
Warning writes a warning message on the screen with the default label
Source Files
Directories
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| Path | Synopsis |
|---|---|
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examples
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basic
command
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rotatedaily
command
|
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rotatehourly
command
|
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slog
command
Example: using gologger as a log/slog handler.
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Example: using gologger as a log/slog handler. |
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tee
command
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