log

README

log

log provides a structured logger with context support.

Refer to examples/app for the source code.

Installation

go get -u github.com/bartventer/log

Usage

package main

import (
    "github.com/bartventer/log"
)

func main() {
    logger := log.New(log.UseLevel(log.DebugLevel))
    
    logger.Debug("Oh, hi!")
}

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

This project is a refactored version of the fantastic charmbracelet/log, which is a part of Charm.

Documentation

Overview

Package log provides a structured logger with context support.

Index

• Constants
• Variables
• func Debug(msg string, args ...slog.Attr)
• func Debugf(format string, args ...any)
• func Default() *slog.Logger
• func Error(msg string, args ...slog.Attr)
• func Errorf(format string, args ...any)
• func Fatal(msg string, args ...slog.Attr)
• func Fatalf(format string, args ...any)
• func Info(msg string, args ...slog.Attr)
• func Infof(format string, args ...any)
• func Log(level Level, msg string, args ...slog.Attr)
• func Logf(level Level, format string, args ...any)
• func New(opts ...Option) *slog.Logger
• func Print(msg string, args ...slog.Attr)
• func SetCallerFormatter(f CallerFormatter, loggers ...*slog.Logger)
• func SetCallerOffset(offset int, loggers ...*slog.Logger)
• func SetFormatter(f Formatter, loggers ...*slog.Logger)
• func SetLevel(level Level, loggers ...*slog.Logger)
• func SetOutput(w io.Writer, loggers ...*slog.Logger)
• func SetPrefix(prefix string, loggers ...*slog.Logger)
• func SetReportCaller(report bool, loggers ...*slog.Logger)
• func SetReportTimestamp(report bool, loggers ...*slog.Logger)
• func SetStyles(s *Styles, loggers ...*slog.Logger)
• func SetTimeFormat(format string, loggers ...*slog.Logger)
• func SetTimeFunction(f TimeFunction, loggers ...*slog.Logger)
• func StandardLog(opts ...StandardLogOption) *stdlog.Logger
• func Warn(msg string, args ...slog.Attr)
• func Warnf(format string, args ...any)
• func WithContext(ctx context.Context, logger Logger) context.Context
• func WithPrefix(l *slog.Logger, prefix string) *slog.Logger
• type CallerFormatter
• type Formatter
• type Level
• type LogOptions
• type Logger
  • func FromContext(ctx context.Context) Logger
• type Option
  • func AsDefault() Option
  • func UseCallerFormatter(f CallerFormatter) Option
  • func UseCallerOffset(offset int) Option
  • func UseFields(fields map[string]slog.Value) Option
  • func UseFormatter(f Formatter) Option
  • func UseLevel(l Level) Option
  • func UseOutput(w io.Writer) Option
  • func UsePrefix(p string) Option
  • func UseReportCaller(r bool) Option
  • func UseReportTimestamp(r bool) Option
  • func UseStyles(s *Styles) Option
  • func UseTimeFormat(f string) Option
  • func UseTimeFunction(f TimeFunction) Option
• type Options
• type StandardLogOption
• type StandardLogOptions
• type Styles
  • func DefaultStyles() *Styles
• type TimeFunction

Constants

const (
	DebugLevel = log.DebugLevel
	InfoLevel  = log.InfoLevel
	WarnLevel  = log.WarnLevel
	ErrorLevel = log.ErrorLevel
	FatalLevel = log.FatalLevel
)

Levels

const (
	TextFormatter   = log.TextFormatter
	JSONFormatter   = log.JSONFormatter
	LogfmtFormatter = log.LogfmtFormatter
)

Formatters

Variables

var (
	ShortCallerFormatter = log.ShortCallerFormatter
	LongCallerFormatter  = log.LongCallerFormatter
)

Caller Formatters

var ContextKey = contextKey{"log"}

ContextKey is the key used to store the logger in context.

Functions

func Debug

func Debug(msg string, args ...slog.Attr)

Debug logs a message with level Debug.

func Debugf

func Debugf(format string, args ...any)

Debugf logs a formatted message with level Debug.

func Default

func Default() *slog.Logger

Default returns the default logger.

func Error

func Error(msg string, args ...slog.Attr)

Error logs a message with level Error.

func Errorf

func Errorf(format string, args ...any)

Errorf logs a formatted message with level Error.

func Fatal

func Fatal(msg string, args ...slog.Attr)

Fatal logs a message with level Fatal and exits with status code 1.

func Fatalf

func Fatalf(format string, args ...any)

Fatalf logs a formatted message with level Fatal and exits with status code 1.

func Info

func Info(msg string, args ...slog.Attr)

Info logs a message with level Info.

func Infof

func Infof(format string, args ...any)

Infof logs a formatted message with level Info.

func Log

func Log(level Level, msg string, args ...slog.Attr)

Log logs a message with the given level.

func Logf

func Logf(level Level, format string, args ...any)

Logf logs a formatted message with the given level.

func New

func New(opts ...Option) *slog.Logger

New creates a new logger with the given options.

func Print

func Print(msg string, args ...slog.Attr)

Print logs a message with no level.

func SetCallerFormatter

func SetCallerFormatter(f CallerFormatter, loggers ...*slog.Logger)

SetCallerFormatter sets the caller formatter.

func SetCallerOffset

func SetCallerOffset(offset int, loggers ...*slog.Logger)

SetCallerOffset sets the caller offset.

func SetFormatter

func SetFormatter(f Formatter, loggers ...*slog.Logger)

SetFormatter sets the formatter.

func SetLevel

func SetLevel(level Level, loggers ...*slog.Logger)

SetLevel sets the level.

func SetOutput

func SetOutput(w io.Writer, loggers ...*slog.Logger)

SetOutput sets the output destination.

func SetPrefix

func SetPrefix(prefix string, loggers ...*slog.Logger)

SetPrefix sets the prefix.

func SetReportCaller

func SetReportCaller(report bool, loggers ...*slog.Logger)

SetReportCaller sets whether to report caller location.

func SetReportTimestamp

func SetReportTimestamp(report bool, loggers ...*slog.Logger)

SetReportTimestamp sets whether to report timestamp.

func SetStyles

func SetStyles(s *Styles, loggers ...*slog.Logger)

SetStyles sets the logger styles.

func SetTimeFormat

func SetTimeFormat(format string, loggers ...*slog.Logger)

SetTimeFormat sets the time format.

func SetTimeFunction

func SetTimeFunction(f TimeFunction, loggers ...*slog.Logger)

SetTimeFunction sets the time function.

func StandardLog

func StandardLog(opts ...StandardLogOption) *stdlog.Logger

StandardLog creates a new standard logger with the given options.

func Warn

func Warn(msg string, args ...slog.Attr)

Warn logs a message with level Warn.

func Warnf

func Warnf(format string, args ...any)

Warnf logs a formatted message with level Warn.

func WithContext

func WithContext(ctx context.Context, logger Logger) context.Context

WithContext wraps the given logger in context.

func WithPrefix

func WithPrefix(l *slog.Logger, prefix string) *slog.Logger

WithPrefix returns a new logger with the given prefix.

Types

type CallerFormatter

type CallerFormatter = log.CallerFormatter

Type aliases

type Formatter

type Formatter = log.Formatter

Type aliases

type Level

type Level = log.Level

Type aliases

type LogOptions

type LogOptions = log.Options

Type aliases

type Logger

type Logger interface {
	Debug(msg string, args ...any)
	DebugContext(ctx context.Context, msg string, args ...any)
	Enabled(ctx context.Context, level slog.Level) bool
	Error(msg string, args ...any)
	ErrorContext(ctx context.Context, msg string, args ...any)
	Handler() slog.Handler
	Info(msg string, args ...any)
	InfoContext(ctx context.Context, msg string, args ...any)
	Log(ctx context.Context, level slog.Level, msg string, args ...any)
	LogAttrs(ctx context.Context, level slog.Level, msg string, attrs ...slog.Attr)
	Warn(msg string, args ...any)
	WarnContext(ctx context.Context, msg string, args ...any)
	With(args ...any) *slog.Logger
	WithGroup(name string) *slog.Logger
}

Logger defines the slog.Logger interface.

func FromContext

func FromContext(ctx context.Context) Logger

FromContext returns the logger from the given context. This will return the default package logger if no logger found in context.

type Option

type Option func(*Options)

Option is a logger option.

func AsDefault

func AsDefault() Option

AsDefault sets the logger as the default logger. Default is false.

func UseCallerFormatter

func UseCallerFormatter(f CallerFormatter) Option

UseCallerFormatter sets the caller formatter option. Default is log.ShortCallerFormatter.

func UseCallerOffset

func UseCallerOffset(offset int) Option

UseCallerOffset sets the caller offset option. Default is 0.

func UseFields

func UseFields(fields map[string]slog.Value) Option

UseFields sets the fields option. Default is no fields.

func UseFormatter

func UseFormatter(f Formatter) Option

UseFormatter sets the formatter option. Default is TextFormatter.

func UseLevel

func UseLevel(l Level) Option

UseLevel sets the level option. Default is log.InfoLevel.

func UseOutput

func UseOutput(w io.Writer) Option

UseOutput sets the writer option. Default is os.Stderr.

func UsePrefix

func UsePrefix(p string) Option

UsePrefix sets the prefix option. Default is no prefix.

func UseReportCaller

func UseReportCaller(r bool) Option

UseReportCaller sets the report caller option. Default is false.

func UseReportTimestamp

func UseReportTimestamp(r bool) Option

UseReportTimestamp sets the report timestamp option. Default is false.

func UseStyles

func UseStyles(s *Styles) Option

UseStyles sets the styles option. Default is DefaultStyles.

func UseTimeFormat

func UseTimeFormat(f string) Option

UseTimeFormat sets the time format option. Default is log.DefaultTimeFormat.

func UseTimeFunction

func UseTimeFunction(f TimeFunction) Option

UseTimeFunction sets the time function option. Default is time.Now.

type Options

type Options struct {
	*LogOptions
	Writer  io.Writer   // Writer is the writer for the logger. Default is [os.Stderr].
	Styles  *log.Styles // Styles is the styles for the logger. Default is [DefaultStyles].
	Default bool        // Default is whether the logger is the default logger. Default is false.
}

Options is the logger options.

type StandardLogOption

type StandardLogOption func(*StandardLogOptions)

StandardLogOption is a standard logger option.

type StandardLogOptions

type StandardLogOptions struct {
	log.StandardLogOptions
	Logger *slog.Logger // Log is the logger to use. Default is the default logger.
}

StandardLogOptions can be used to configure the standard log adapter.

type Styles

type Styles = log.Styles

Type aliases

func DefaultStyles

func DefaultStyles() *Styles

DefaultStyles returns the default styles. It applies custom styles to the log.DefaultStyles.

type TimeFunction

type TimeFunction = func(time.Time) time.Time

Type aliases