logger

README

Simple structured logger for Go

A simple logger package that provides levels, a number of output formats, and named sub-logs. Output formats include key/value, JSON and AMQP/RabbitMQ

Installation

Install using go get github.com/felix/logger.

Documentation is available at http://godoc.org/github.com/felix/logger

Usage

Create a key/value logger

log := logger.New(logger.Name("app"), logger.Level(logger.DEBUG))
log.Error("unable to do anything")

... [info] app: unable to do anything

log.Warn("invalid something", "id", 344, "error", "generally broken")

Add structure

... [warn] app: invalid something id=344 error="generally broken"

Create a sub-logger

sublog := log.GetNamed("database")
sublog.Info("connection initialised")

... [info] app.database: connection initialised

Create a new Logger with pre-defined values

For major sub-systems there is no need to repeat values for each log call:

reqID := "555"
msgLog := sublog.WithField("request", reqID)
msgLog.Error("failed to process message")

... [info] app.database: failed to process message request=555

Comparison

BenchmarkCoreLogger-12           5000000               288 ns/op
BenchmarkLocal-12                2000000               654 ns/op
BenchmarkLogrus-12               1000000              1738 ns/op
BenchmarkFieldsLocal-12          1000000              1024 ns/op
BenchmarkFieldsLogrus-12         1000000              2061 ns/op

Documentation

Index

• func Debug(msg string, args ...interface{})
• func Error(msg string, args ...interface{})
• func Info(msg string, args ...interface{})
• func IsDebug() bool
• func IsInfo() bool
• func IsWarn() bool
• func SetField(k string, v interface{})
• func SetLevel(lvl message.Level)
• func SetLevelString(lvl string)
• func SetName(n string)
• func Warn(msg string, args ...interface{})
• type Logger
  • func GetNamed(n string) *Logger
  • func New(opts ...Option) (*Logger, error)
  • func (l *Logger) Configure(opts ...Option) error
  • func (l *Logger) Debug(msg string, args ...interface{})
  • func (l *Logger) Error(msg string, args ...interface{})
  • func (l *Logger) GetNamed(n string) *Logger
  • func (l *Logger) Info(msg string, args ...interface{})
  • func (l *Logger) IsDebug() bool
  • func (l *Logger) IsInfo() bool
  • func (l *Logger) IsWarn() bool
  • func (l *Logger) Log(lvl message.Level, msg string, args ...interface{})
  • func (l *Logger) SetField(k string, v interface{})
  • func (l *Logger) SetLevel(lvl message.Level)
  • func (l *Logger) SetLevelString(lvl string)
  • func (l *Logger) SetName(n string)
  • func (l *Logger) Warn(msg string, args ...interface{})
• type Option
  • func Field(k string, v interface{}) Option
  • func Fields(f map[string]interface{}) Option
  • func Level(lvl message.Level) Option
  • func LevelString(lvl string) Option
  • func Name(n string) Option
  • func Writer(f message.Writer) Option

Functions

func Debug

func Debug(msg string, args ...interface{})

Debug logs a debug message.

func Error

func Error(msg string, args ...interface{})

Error logs an error message.

func Info

func Info(msg string, args ...interface{})

Info logs an information message.

func IsDebug

func IsDebug() bool

IsDebug determines the debug status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func IsInfo

func IsInfo() bool

IsInfo determines the info status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func IsWarn

func IsWarn() bool

IsWarn determines the info status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func SetField

func SetField(k string, v interface{})

SetField enables changing the default fields for a logger instance.

func SetLevel

func SetLevel(lvl message.Level)

SetLevel enables changing the minimum level for a logger instance.

func SetLevelString

func SetLevelString(lvl string)

SetLevelString enables changing the minimum level for a logger instance.

func SetName

func SetName(n string)

SetName enables changing the name for a logger instance.

func Warn

func Warn(msg string, args ...interface{})

Warn logs an information message.

Types

type Logger

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

Logger is a simple levelled logger.

func GetNamed

func GetNamed(n string) *Logger

GetNamed creates a new instance of a logger with a new name.

func New

func New(opts ...Option) (*Logger, error)

New creates a new logger instance

func (*Logger) Configure

func (l *Logger) Configure(opts ...Option) error

Configure applies settings to the logger.

func (*Logger) Debug

func (l *Logger) Debug(msg string, args ...interface{})

Debug logs a debug message.

func (*Logger) Error

func (l *Logger) Error(msg string, args ...interface{})

Error logs an error message.

func (*Logger) GetNamed

func (l *Logger) GetNamed(n string) *Logger

GetNamed creates a new instance of a logger with a new name.

func (*Logger) Info

func (l *Logger) Info(msg string, args ...interface{})

Info logs an information message.

func (*Logger) IsDebug

func (l *Logger) IsDebug() bool

IsDebug determines the debug status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func (*Logger) IsInfo

func (l *Logger) IsInfo() bool

IsInfo determines the info status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func (*Logger) IsWarn

func (l *Logger) IsWarn() bool

IsWarn determines the info status for a logger instance. Use this to conditionally execute blocks of code depending on the log verbosity.

func (*Logger) Log

func (l *Logger) Log(lvl message.Level, msg string, args ...interface{})

Log for a logger instance

func (*Logger) SetField

func (l *Logger) SetField(k string, v interface{})

SetField enables changing the default fields for a logger instance.

func (*Logger) SetLevel

func (l *Logger) SetLevel(lvl message.Level)

SetLevel enables changing the minimum level for a logger instance.

func (*Logger) SetLevelString

func (l *Logger) SetLevelString(lvl string)

SetLevelString enables changing the minimum level for a logger instance.

func (*Logger) SetName

func (l *Logger) SetName(n string)

SetName enables changing the name for a logger instance.

func (*Logger) Warn

func (l *Logger) Warn(msg string, args ...interface{})

Warn logs an information message.

type Option

type Option func(*Logger) error

An Option configures a logger

func Field

func Field(k string, v interface{}) Option

Field configures an initial field of the logger.

func Fields

func Fields(f map[string]interface{}) Option

Fields configures an initial set of fields of the logger.

func Level

func Level(lvl message.Level) Option

Level configures the minimum level to log.

func LevelString

func LevelString(lvl string) Option

LevelString configures the minimum level to log.

func Name

func Name(n string) Option

Name configures the name of the logger.

func Writer

func Writer(f message.Writer) Option

Writer add an output formatter for the logger.