logs

README

logs

Simple, pretty logger for your Go apps.

log := logs.Default()
log.WithGroup("grouped").Debug("debug line", "path", "console_test.go")
log.Info("some info")
log.Warn("some warning")
log.Error("an error", "err", errors.New("oh no"))

Features

• Compatible with slog
• Pretty console handler for terminals
• Adds a level filter handler
• Adds a concurrent multi-logger

Install

go get github.com/matthewmueller/logs

Example

// Go with the default logger
log := logs.Default()

// Or configure
log = logs.New(
  logs.Multi(
    logs.Filter(slog.LevelInfo, logs.Console(os.Stderr)),
    slog.NewJSONHandler(os.Stderr, nil),
  ),
)

log.WithGroup("hello").Debug("world", "args", 10)
log.Info("hello", "planet", "world", "args", 10)
log.Warn("hello", "planet", "world", "args", 10)
log.Error("hello world", "planet", "world", "args", 10)

// Integrates well with other libraries because log is still a *slog.Logger
var logger *slog.Logger = log
logger.WithGroup("hello").Debug("world", "args", 10)
logger.Info("hello", "planet", "world", "args", 10)
logger.Warn("hello", "planet", "world", "args", 10)
logger.Error("hello world", slog.String("planet", "world"), "args", 10)

Contributors

• Matt Mueller (@mattmueller)

License

MIT

Documentation

Index

• func Debug(msg string, args ...any)
• func DebugContext(ctx context.Context, msg string, args ...any)
• func Error(msg string, args ...any)
• func ErrorContext(ctx context.Context, msg string, args ...any)
• func Info(msg string, args ...any)
• func InfoContext(ctx context.Context, msg string, args ...any)
• func ParseLevel(level string) (slog.Level, error)
• func Warn(msg string, args ...any)
• func WarnContext(ctx context.Context, msg string, args ...any)
• type ConsoleHandler
  • func Console(w io.Writer) *ConsoleHandler
  • func (c *ConsoleHandler) Enabled(context.Context, slog.Level) bool
  • func (c *ConsoleHandler) Handle(ctx context.Context, record slog.Record) error
  • func (c *ConsoleHandler) WithAttrs(attrs []slog.Attr) slog.Handler
  • func (c *ConsoleHandler) WithGroup(group string) slog.Handler
• type FilterHandler
  • func Filter(level slog.Level, handler slog.Handler) *FilterHandler
  • func (f *FilterHandler) Enabled(ctx context.Context, l slog.Level) bool
  • func (f *FilterHandler) Handle(ctx context.Context, record slog.Record) error
  • func (f *FilterHandler) WithAttrs(attrs []slog.Attr) slog.Handler
  • func (f *FilterHandler) WithGroup(group string) slog.Handler
• type Handler
• type Logger
  • func Default() *Logger
  • func Discard() *Logger
  • func New(handler slog.Handler) *Logger
  • func Scope(log *Logger) *Logger
• type MultiHandler
  • func Multi(handlers ...slog.Handler) MultiHandler
  • func (handlers MultiHandler) Enabled(ctx context.Context, lvl slog.Level) bool
  • func (handlers MultiHandler) Handle(ctx context.Context, record slog.Record) error
  • func (handlers MultiHandler) WithAttrs(attrs []slog.Attr) slog.Handler
  • func (handlers MultiHandler) WithGroup(group string) slog.Handler

Examples

• Console
• Default
• Discard
• Logger
• Multi

Functions

func Debug

func Debug(msg string, args ...any)

Debug calls [Logger.Debug] on the default logger.

func DebugContext

func DebugContext(ctx context.Context, msg string, args ...any)

DebugContext calls [Logger.DebugContext] on the default logger.

func Error

func Error(msg string, args ...any)

Error calls [Logger.Error] on the default logger.

func ErrorContext

func ErrorContext(ctx context.Context, msg string, args ...any)

ErrorContext calls [Logger.ErrorContext] on the default logger.

func Info

func Info(msg string, args ...any)

Info calls [Logger.Info] on the default logger.

func InfoContext

func InfoContext(ctx context.Context, msg string, args ...any)

InfoContext calls [Logger.InfoContext] on the default logger.

func ParseLevel

func ParseLevel(level string) (slog.Level, error)

ParseLevel parses a string into a log level

func Warn

func Warn(msg string, args ...any)

Warn calls [Logger.Warn] on the default logger.

func WarnContext

func WarnContext(ctx context.Context, msg string, args ...any)

WarnContext calls [Logger.WarnContext] on the default logger.

Types

type ConsoleHandler

type ConsoleHandler struct {
	Color  color.Writer
	Source bool
	// contains filtered or unexported fields
}

ConsoleHandler handler for printing logs to the terminal

func Console

func Console(w io.Writer) *ConsoleHandler

Example

package main

import (
	"errors"
	"os"

	"github.com/livebud/color"
	"github.com/matthewmueller/logs"
)

func main() {
	console := logs.Console(os.Stdout)
	console.Color = color.Ignore()
	log := logs.New(console)
	log.WithGroup("grouped").Debug("debug line", "path", "console_test.go")
	log.Info("some info")
	log.Warn("some warning")
	log.Error("an error", "err", errors.New("oh no"))
}

Output:

debug: debug line grouped.path=console_test.go
info: some info
warn: some warning
error: an error err="oh no"

func (*ConsoleHandler) Enabled

func (c *ConsoleHandler) Enabled(context.Context, slog.Level) bool

Enabled is always set to true. Use log.Filter to filter out log levels

func (*ConsoleHandler) Handle

func (c *ConsoleHandler) Handle(ctx context.Context, record slog.Record) error

func (*ConsoleHandler) WithAttrs

func (c *ConsoleHandler) WithAttrs(attrs []slog.Attr) slog.Handler

func (*ConsoleHandler) WithGroup

func (c *ConsoleHandler) WithGroup(group string) slog.Handler

type FilterHandler

type FilterHandler struct {
	// contains filtered or unexported fields
}

func Filter

func Filter(level slog.Level, handler slog.Handler) *FilterHandler

Filter logs by level

func (*FilterHandler) Enabled

func (f *FilterHandler) Enabled(ctx context.Context, l slog.Level) bool

func (*FilterHandler) Handle

func (f *FilterHandler) Handle(ctx context.Context, record slog.Record) error

func (*FilterHandler) WithAttrs

func (f *FilterHandler) WithAttrs(attrs []slog.Attr) slog.Handler

func (*FilterHandler) WithGroup

func (f *FilterHandler) WithGroup(group string) slog.Handler

type Handler

type Handler = slog.Handler

type Logger

type Logger = slog.Logger

Example

package main

import (
	"log/slog"
	"os"

	"github.com/livebud/color"
	"github.com/matthewmueller/logs"
)

func main() {
	console := logs.Console(os.Stdout)
	console.Color = color.Ignore()
	log := logs.New(console)
	var logger *slog.Logger = log
	logger.WithGroup("hello").Debug("world", "args", 10)
	logger.Info("hello", "planet", "world", "args", 10)
	logger.Warn("hello", "planet", "world", "args", 10)
	logger.Error("hello world", slog.String("planet", "world"), "args", 10)
}

Output:

debug: world hello.args=10
info: hello planet=world args=10
warn: hello planet=world args=10
error: hello world planet=world args=10

func Default

func Default() *Logger

Example

package main

import (
	"github.com/matthewmueller/logs"
)

func main() {
	logs.Info("hello", "planet", "world", "args", 10)
	// No output because default logger logs to stderr
	

func Discard

func Discard() *Logger

Example

package main

import (
	"log/slog"

	"github.com/matthewmueller/logs"
)

func main() {
	log := logs.Discard()
	var logger *slog.Logger = log
	logger.WithGroup("hello").Debug("world", "args", 10)
	logger.Info("hello", "planet", "world", "args", 10)
	logger.Warn("hello", "planet", "world", "args", 10)
	logger.Error("hello world", slog.String("planet", "world"), "args", 10)
}

func New

func New(handler slog.Handler) *Logger

func Scope

func Scope(log *Logger) *Logger

Scope adds the funcion, filename and line number to the log

type MultiHandler

type MultiHandler []slog.Handler

func Multi

func Multi(handlers ...slog.Handler) MultiHandler

Example

package main

import (
	"log/slog"
	"os"

	"github.com/matthewmueller/logs"
)

func main() {
	console := logs.Console(os.Stderr)
	log := slog.New(logs.Multi(
		logs.Filter(slog.LevelInfo, console),
		slog.NewJSONHandler(os.Stderr, nil),
	))
	log.WithGroup("hello").Debug("world", "args", 10)
	log.Info("hello", "planet", "world", "args", 10)
	log.Warn("hello", "planet", "world", "args", 10)
	log.Error("hello world", "planet", "world", "args", 10)
}

func (MultiHandler) Enabled

func (handlers MultiHandler) Enabled(ctx context.Context, lvl slog.Level) bool

func (MultiHandler) Handle

func (handlers MultiHandler) Handle(ctx context.Context, record slog.Record) error

func (MultiHandler) WithAttrs

func (handlers MultiHandler) WithAttrs(attrs []slog.Attr) slog.Handler

func (MultiHandler) WithGroup

func (handlers MultiHandler) WithGroup(group string) slog.Handler