log

Documentation

Overview

Package log provides a global logger.

Example

This example uses command-line flags to demonstrate various outputs depending on the chosen log level.

package main

import (
	"flag"
	"os"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// setup would normally be an init() function, however, there seems
// to be something awry with the testing framework when we set the
// global Logger from an init()
func setup() {

	zerolog.TimeFieldFormat = ""

	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
	}
	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
}

func main() {
	setup()
	debug := flag.Bool("debug", false, "sets log level to debug")

	flag.Parse()

	// Default level for this example is info, unless debug flag is present
	zerolog.SetGlobalLevel(zerolog.InfoLevel)
	if *debug {
		zerolog.SetGlobalLevel(zerolog.DebugLevel)
	}

	log.Debug().Msg("This message appears only when log level set to Debug")
	log.Info().Msg("This message appears when log level set to Debug or Info")

	if e := log.Debug(); e.Enabled() {
		// Compute log output only if enabled.
		value := "bar"
		e.Str("foo", value).Msg("some debug message")
	}

}

Output:

{"level":"info","time":1199811905,"message":"This message appears when log level set to Debug or Info"}

Index

• Variables
• func Debug() *zerolog.Event
• func Error() *zerolog.Event
• func Fatal() *zerolog.Event
• func Info() *zerolog.Event

Examples

• Package
• Debug
• Error
• Fatal
• Info

Variables

var Logger = zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: time.RFC3339}).With().Timestamp().Logger()

Logger is the global logger.

Functions

func Debug

func Debug() *zerolog.Event

Debug starts a new message with debug level.

You must call Msg on the returned event in order to send the event.

Example

Example of a log at a particular "level" (in this case, "debug")

package main

import (
	"os"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// setup would normally be an init() function, however, there seems
// to be something awry with the testing framework when we set the
// global Logger from an init()
func setup() {

	zerolog.TimeFieldFormat = ""

	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
	}
	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
}

func main() {
	setup()
	log.Debug().Msg("hello world")

}

Output:

{"level":"debug","time":1199811905,"message":"hello world"}

func Error

func Error() *zerolog.Event

Error starts a new message with error level.

You must call Msg on the returned event in order to send the event.

Example

Example of a log at a particular "level" (in this case, "error")

package main

import (
	"os"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// setup would normally be an init() function, however, there seems
// to be something awry with the testing framework when we set the
// global Logger from an init()
func setup() {

	zerolog.TimeFieldFormat = ""

	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
	}
	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
}

func main() {
	setup()
	log.Error().Msg("hello world")

}

Output:

{"level":"error","time":1199811905,"message":"hello world"}

func Fatal

func Fatal() *zerolog.Event

Fatal starts a new message with fatal level. The os.Exit(1) function is called by the Msg method.

You must call Msg on the returned event in order to send the event.

Example

Example of a log at a particular "level" (in this case, "fatal")

package main

import (
	"errors"
	"os"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// setup would normally be an init() function, however, there seems
// to be something awry with the testing framework when we set the
// global Logger from an init()
func setup() {

	zerolog.TimeFieldFormat = ""

	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
	}
	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
}

func main() {
	setup()
	err := errors.New("A repo man spends his life getting into tense situations")
	service := "myservice"

	log.Fatal().
		Err(err).
		Str("service", service).
		Msgf("Cannot start %s", service)

	// Outputs: {"level":"fatal","time":1199811905,"error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"}
}

func Info

func Info() *zerolog.Event

Info starts a new message with info level.

You must call Msg on the returned event in order to send the event.

Example

Example of a log at a particular "level" (in this case, "info")

package main

import (
	"os"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// setup would normally be an init() function, however, there seems
// to be something awry with the testing framework when we set the
// global Logger from an init()
func setup() {

	zerolog.TimeFieldFormat = ""

	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC)
	}
	log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
}

func main() {
	setup()
	log.Info().Msg("hello world")

}

Output:

{"level":"info","time":1199811905,"message":"hello world"}