zerolog: github.com/rs/zerolog Index | Examples | Files | Directories

package zerolog

import "github.com/rs/zerolog"

Package zerolog provides a lightweight logging library dedicated to JSON logging.

A global Logger can be use for simple logging:

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

log.Info().Msg("hello world")
// Output: {"time":1494567715,"level":"info","message":"hello world"}

NOTE: To import the global logger, import the "log" subpackage "github.com/rs/zerolog/log".

Fields can be added to log messages:

log.Info().Str("foo", "bar").Msg("hello world")
// Output: {"time":1494567715,"level":"info","message":"hello world","foo":"bar"}

Create logger instance to manage different outputs:

logger := zerolog.New(os.Stderr).With().Timestamp().Logger()
logger.Info().
       Str("foo", "bar").
       Msg("hello world")
// Output: {"time":1494567715,"level":"info","message":"hello world","foo":"bar"}

Sub-loggers let you chain loggers with additional context:

sublogger := log.With().Str("component": "foo").Logger()
sublogger.Info().Msg("hello world")
// Output: {"time":1494567715,"level":"info","message":"hello world","component":"foo"}

Level logging

zerolog.SetGlobalLevel(zerolog.InfoLevel)

log.Debug().Msg("filtered out message")
log.Info().Msg("routed message")

if e := log.Debug(); e.Enabled() {
    // Compute log output only if enabled.
    value := compute()
    e.Str("foo": value).Msg("some debug message")
}
// Output: {"level":"info","time":1494567715,"routed message"}

Customize automatic field names:

log.TimestampFieldName = "t"
log.LevelFieldName = "p"
log.MessageFieldName = "m"

log.Info().Msg("hello world")
// Output: {"t":1494567715,"p":"info","m":"hello world"}

Log with no level and message:

log.Log().Str("foo","bar").Msg("")
// Output: {"time":1494567715,"foo":"bar"}

Add contextual fields to global Logger:

log.Logger = log.With().Str("foo", "bar").Logger()

Sample logs:

sampled := log.Sample(&zerolog.BasicSampler{N: 10})
sampled.Info().Msg("will be logged every 10 messages")

Log with contextual hooks:

// Create the hook:
type SeverityHook struct{}

func (h SeverityHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
     if level != zerolog.NoLevel {
         e.Str("severity", level.String())
     }
}

// And use it:
var h SeverityHook
log := zerolog.New(os.Stdout).Hook(h)
log.Warn().Msg("")
// Output: {"level":"warn","severity":"warn"}

Caveats

There is no fields deduplication out-of-the-box. Using the same key multiple times creates new key in final JSON each time.

logger := zerolog.New(os.Stderr).With().Timestamp().Logger()
logger.Info().
       Timestamp().
       Msg("dup")
// Output: {"level":"info","time":1494567715,"time":1494567715,"message":"dup"}

In this case, many consumers will take the last value, but this is not guaranteed; check yours if in doubt.

Index

Examples

Package Files

array.go console.go context.go ctx.go encoder.go encoder_json.go event.go fields.go globals.go go112.go hook.go log.go sampler.go syslog.go writer.go

Constants

const (
    // TimeFormatUnix defines a time format that makes time fields to be
    // serialized as Unix timestamp integers.
    TimeFormatUnix = ""

    // TimeFormatUnix defines a time format that makes time fields to be
    // serialized as Unix timestamp integers in milliseconds.
    TimeFormatUnixMs = "UNIXMS"
)

Variables

var (
    // TimestampFieldName is the field name used for the timestamp field.
    TimestampFieldName = "time"

    // LevelFieldName is the field name used for the level field.
    LevelFieldName = "level"

    // LevelFieldMarshalFunc allows customization of global level field marshaling
    LevelFieldMarshalFunc = func(l Level) string {
        return l.String()
    }

    // MessageFieldName is the field name used for the message field.
    MessageFieldName = "message"

    // ErrorFieldName is the field name used for error fields.
    ErrorFieldName = "error"

    // CallerFieldName is the field name used for caller field.
    CallerFieldName = "caller"

    // CallerSkipFrameCount is the number of stack frames to skip to find the caller.
    CallerSkipFrameCount = 2

    // CallerMarshalFunc allows customization of global caller marshaling
    CallerMarshalFunc = func(file string, line int) string {
        return file + ":" + strconv.Itoa(line)
    }

    // ErrorStackFieldName is the field name used for error stacks.
    ErrorStackFieldName = "stack"

    // ErrorStackMarshaler extract the stack from err if any.
    ErrorStackMarshaler func(err error) interface{}

    // ErrorMarshalFunc allows customization of global error marshaling
    ErrorMarshalFunc = func(err error) interface{} {
        return err
    }

    // TimeFieldFormat defines the time format of the Time field type. If set to
    // TimeFormatUnix or TimeFormatUnixMs, the time is formatted as an UNIX
    // timestamp as integer.
    TimeFieldFormat = time.RFC3339

    // TimestampFunc defines the function called to generate a timestamp.
    TimestampFunc = time.Now

    // DurationFieldUnit defines the unit for time.Duration type fields added
    // using the Dur method.
    DurationFieldUnit = time.Millisecond

    // DurationFieldInteger renders Dur fields as integer instead of float if
    // set to true.
    DurationFieldInteger = false

    // ErrorHandler is called whenever zerolog fails to write an event on its
    // output. If not set, an error is printed on the stderr. This handler must
    // be thread safe and non-blocking.
    ErrorHandler func(err error)
)
var (
    // Often samples log every ~ 10 events.
    Often = RandomSampler(10)
    // Sometimes samples log every ~ 100 events.
    Sometimes = RandomSampler(100)
    // Rarely samples log every ~ 1000 events.
    Rarely = RandomSampler(1000)
)

func DisableSampling Uses

func DisableSampling(v bool)

DisableSampling will disable sampling in all Loggers if true.

func SetGlobalLevel Uses

func SetGlobalLevel(l Level)

SetGlobalLevel sets the global override for log level. If this values is raised, all Loggers will use at least this value.

To globally disable logs, set GlobalLevel to Disabled.

func SyncWriter Uses

func SyncWriter(w io.Writer) io.Writer

SyncWriter wraps w so that each call to Write is synchronized with a mutex. This syncer can be the call to writer's Write method is not thread safe. Note that os.File Write operation is using write() syscall which is supposed to be thread-safe on POSIX systems. So there is no need to use this with os.File on such systems as zerolog guaranties to issue a single Write call per log event.

type Array Uses

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

Array is used to prepopulate an array of items which can be re-used to add to log messages.

func Arr Uses

func Arr() *Array

Arr creates an array to be added to an Event or Context.

func (*Array) Bool Uses

func (a *Array) Bool(b bool) *Array

Bool append append the val as a bool to the array.

func (*Array) Bytes Uses

func (a *Array) Bytes(val []byte) *Array

Bytes append append the val as a string to the array.

func (*Array) Dur Uses

func (a *Array) Dur(d time.Duration) *Array

Dur append append d to the array.

func (*Array) Err Uses

func (a *Array) Err(err error) *Array

Err serializes and appends the err to the array.

func (*Array) Float32 Uses

func (a *Array) Float32(f float32) *Array

Float32 append append f as a float32 to the array.

func (*Array) Float64 Uses

func (a *Array) Float64(f float64) *Array

Float64 append append f as a float64 to the array.

func (*Array) Hex Uses

func (a *Array) Hex(val []byte) *Array

Hex append append the val as a hex string to the array.

func (*Array) IPAddr Uses

func (a *Array) IPAddr(ip net.IP) *Array

IPAddr adds IPv4 or IPv6 address to the array

func (*Array) IPPrefix Uses

func (a *Array) IPPrefix(pfx net.IPNet) *Array

IPPrefix adds IPv4 or IPv6 Prefix (IP + mask) to the array

func (*Array) Int Uses

func (a *Array) Int(i int) *Array

Int append append i as a int to the array.

func (*Array) Int16 Uses

func (a *Array) Int16(i int16) *Array

Int16 append append i as a int16 to the array.

func (*Array) Int32 Uses

func (a *Array) Int32(i int32) *Array

Int32 append append i as a int32 to the array.

func (*Array) Int64 Uses

func (a *Array) Int64(i int64) *Array

Int64 append append i as a int64 to the array.

func (*Array) Int8 Uses

func (a *Array) Int8(i int8) *Array

Int8 append append i as a int8 to the array.

func (*Array) Interface Uses

func (a *Array) Interface(i interface{}) *Array

Interface append append i marshaled using reflection.

func (*Array) MACAddr Uses

func (a *Array) MACAddr(ha net.HardwareAddr) *Array

MACAddr adds a MAC (Ethernet) address to the array

func (*Array) MarshalZerologArray Uses

func (*Array) MarshalZerologArray(*Array)

MarshalZerologArray method here is no-op - since data is already in the needed format.

func (*Array) Object Uses

func (a *Array) Object(obj LogObjectMarshaler) *Array

Object marshals an object that implement the LogObjectMarshaler interface and append append it to the array.

func (*Array) Str Uses

func (a *Array) Str(val string) *Array

Str append append the val as a string to the array.

func (*Array) Time Uses

func (a *Array) Time(t time.Time) *Array

Time append append t formated as string using zerolog.TimeFieldFormat.

func (*Array) Uint Uses

func (a *Array) Uint(i uint) *Array

Uint append append i as a uint to the array.

func (*Array) Uint16 Uses

func (a *Array) Uint16(i uint16) *Array

Uint16 append append i as a uint16 to the array.

func (*Array) Uint32 Uses

func (a *Array) Uint32(i uint32) *Array

Uint32 append append i as a uint32 to the array.

func (*Array) Uint64 Uses

func (a *Array) Uint64(i uint64) *Array

Uint64 append append i as a uint64 to the array.

func (*Array) Uint8 Uses

func (a *Array) Uint8(i uint8) *Array

Uint8 append append i as a uint8 to the array.

type BasicSampler Uses

type BasicSampler struct {
    N uint32
    // contains filtered or unexported fields
}

BasicSampler is a sampler that will send every Nth events, regardless of there level.

func (*BasicSampler) Sample Uses

func (s *BasicSampler) Sample(lvl Level) bool

Sample implements the Sampler interface.

type BurstSampler Uses

type BurstSampler struct {
    // Burst is the maximum number of event per period allowed before calling
    // NextSampler.
    Burst uint32
    // Period defines the burst period. If 0, NextSampler is always called.
    Period time.Duration
    // NextSampler is the sampler used after the burst is reached. If nil,
    // events are always rejected after the burst.
    NextSampler Sampler
    // contains filtered or unexported fields
}

BurstSampler lets Burst events pass per Period then pass the decision to NextSampler. If Sampler is not set, all subsequent events are rejected.

func (*BurstSampler) Sample Uses

func (s *BurstSampler) Sample(lvl Level) bool

Sample implements the Sampler interface.

type ConsoleWriter Uses

type ConsoleWriter struct {
    // Out is the output destination.
    Out io.Writer

    // NoColor disables the colorized output.
    NoColor bool

    // TimeFormat specifies the format for timestamp in output.
    TimeFormat string

    // PartsOrder defines the order of parts in output.
    PartsOrder []string

    FormatTimestamp     Formatter
    FormatLevel         Formatter
    FormatCaller        Formatter
    FormatMessage       Formatter
    FormatFieldName     Formatter
    FormatFieldValue    Formatter
    FormatErrFieldName  Formatter
    FormatErrFieldValue Formatter
}

ConsoleWriter parses the JSON input and writes it in an (optionally) colorized, human-friendly format to Out.

Code:

log := zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, NoColor: true})

log.Info().Str("foo", "bar").Msg("Hello World")

Output:

<nil> INF Hello World foo=bar

Code:

out := zerolog.ConsoleWriter{Out: os.Stdout, NoColor: true}
out.FormatLevel = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%-6s|", i)) }
out.FormatFieldName = func(i interface{}) string { return fmt.Sprintf("%s:", i) }
out.FormatFieldValue = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("%s", i)) }
log := zerolog.New(out)

log.Info().Str("foo", "bar").Msg("Hello World")

Output:

<nil> INFO  | Hello World foo:BAR

func NewConsoleWriter Uses

func NewConsoleWriter(options ...func(w *ConsoleWriter)) ConsoleWriter

NewConsoleWriter creates and initializes a new ConsoleWriter.

Code:

out := zerolog.NewConsoleWriter()
out.NoColor = true // For testing purposes only
log := zerolog.New(out)

log.Debug().Str("foo", "bar").Msg("Hello World")

Output:

<nil> DBG Hello World foo=bar

Code:

out := zerolog.NewConsoleWriter(
    func(w *zerolog.ConsoleWriter) {
        // Customize time format
        w.TimeFormat = time.RFC822
        // Customize level formatting
        w.FormatLevel = func(i interface{}) string { return strings.ToUpper(fmt.Sprintf("[%-5s]", i)) }
    },
)
out.NoColor = true // For testing purposes only

log := zerolog.New(out)

log.Info().Str("foo", "bar").Msg("Hello World")

Output:

<nil> [INFO ] Hello World foo=bar

func (ConsoleWriter) Write Uses

func (w ConsoleWriter) Write(p []byte) (n int, err error)

Write transforms the JSON input with formatters and appends to w.Out.

type Context Uses

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

Context configures a new sub-logger with contextual fields.

func (Context) AnErr Uses

func (c Context) AnErr(key string, err error) Context

AnErr adds the field key with serialized err to the logger context.

func (Context) Array Uses

func (c Context) Array(key string, arr LogArrayMarshaler) Context

Array adds the field key with an array to the event context. Use zerolog.Arr() to create the array or pass a type that implement the LogArrayMarshaler interface.

Code:

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Array("array", zerolog.Arr().
        Str("baz").
        Int(1),
    ).Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","array":["baz",1],"message":"hello world"}

Code:

// Users implements zerolog.LogArrayMarshaler
u := Users{
    User{"John", 35, time.Time{}},
    User{"Bob", 55, time.Time{}},
}

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Array("users", u).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}

func (Context) Bool Uses

func (c Context) Bool(key string, b bool) Context

Bool adds the field key with val as a bool to the logger context.

func (Context) Bools Uses

func (c Context) Bools(key string, b []bool) Context

Bools adds the field key with val as a []bool to the logger context.

func (Context) Bytes Uses

func (c Context) Bytes(key string, val []byte) Context

Bytes adds the field key with val as a []byte to the logger context.

func (Context) Caller Uses

func (c Context) Caller() Context

Caller adds the file:line of the caller with the zerolog.CallerFieldName key.

func (Context) CallerWithSkipFrameCount Uses

func (c Context) CallerWithSkipFrameCount(skipFrameCount int) Context

CallerWithSkipFrameCount adds the file:line of the caller with the zerolog.CallerFieldName key. The specified skipFrameCount int will override the global CallerSkipFrameCount for this context's respective logger. If set to -1 the global CallerSkipFrameCount will be used.

func (Context) Dict Uses

func (c Context) Dict(key string, dict *Event) Context

Dict adds the field key with the dict to the logger context.

Code:

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Dict("dict", zerolog.Dict().
        Str("bar", "baz").
        Int("n", 1),
    ).Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}

func (Context) Dur Uses

func (c Context) Dur(key string, d time.Duration) Context

Dur adds the fields key with d divided by unit and stored as a float.

Code:

d := time.Duration(10 * time.Second)

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Dur("dur", d).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","dur":10000,"message":"hello world"}

func (Context) Durs Uses

func (c Context) Durs(key string, d []time.Duration) Context

Durs adds the fields key with d divided by unit and stored as a float.

Code:

d := []time.Duration{
    time.Duration(10 * time.Second),
    time.Duration(20 * time.Second),
}

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Durs("durs", d).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","durs":[10000,20000],"message":"hello world"}

func (Context) EmbedObject Uses

func (c Context) EmbedObject(obj LogObjectMarshaler) Context

EmbedObject marshals and Embeds an object that implement the LogObjectMarshaler interface.

Code:

price := Price{val: 6449, prec: 2, unit: "$"}

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    EmbedObject(price).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","price":"$64.49","message":"hello world"}

func (Context) Err Uses

func (c Context) Err(err error) Context

Err adds the field "error" with serialized err to the logger context.

func (Context) Errs Uses

func (c Context) Errs(key string, errs []error) Context

Errs adds the field key with errs as an array of serialized errors to the logger context.

func (Context) Fields Uses

func (c Context) Fields(fields map[string]interface{}) Context

Fields is a helper function to use a map to set fields using type assertion.

func (Context) Float32 Uses

func (c Context) Float32(key string, f float32) Context

Float32 adds the field key with f as a float32 to the logger context.

func (Context) Float64 Uses

func (c Context) Float64(key string, f float64) Context

Float64 adds the field key with f as a float64 to the logger context.

func (Context) Floats32 Uses

func (c Context) Floats32(key string, f []float32) Context

Floats32 adds the field key with f as a []float32 to the logger context.

func (Context) Floats64 Uses

func (c Context) Floats64(key string, f []float64) Context

Floats64 adds the field key with f as a []float64 to the logger context.

func (Context) Hex Uses

func (c Context) Hex(key string, val []byte) Context

Hex adds the field key with val as a hex string to the logger context.

func (Context) IPAddr Uses

func (c Context) IPAddr(key string, ip net.IP) Context

IPAddr adds IPv4 or IPv6 Address to the context

Code:

hostIP := net.IP{192, 168, 0, 100}
log := zerolog.New(os.Stdout).With().
    IPAddr("HostIP", hostIP).
    Logger()

log.Log().Msg("hello world")

Output:

{"HostIP":"192.168.0.100","message":"hello world"}

func (Context) IPPrefix Uses

func (c Context) IPPrefix(key string, pfx net.IPNet) Context

IPPrefix adds IPv4 or IPv6 Prefix (address and mask) to the context

Code:

route := net.IPNet{IP: net.IP{192, 168, 0, 0}, Mask: net.CIDRMask(24, 32)}
log := zerolog.New(os.Stdout).With().
    IPPrefix("Route", route).
    Logger()

log.Log().Msg("hello world")

Output:

{"Route":"192.168.0.0/24","message":"hello world"}

func (Context) Int Uses

func (c Context) Int(key string, i int) Context

Int adds the field key with i as a int to the logger context.

func (Context) Int16 Uses

func (c Context) Int16(key string, i int16) Context

Int16 adds the field key with i as a int16 to the logger context.

func (Context) Int32 Uses

func (c Context) Int32(key string, i int32) Context

Int32 adds the field key with i as a int32 to the logger context.

func (Context) Int64 Uses

func (c Context) Int64(key string, i int64) Context

Int64 adds the field key with i as a int64 to the logger context.

func (Context) Int8 Uses

func (c Context) Int8(key string, i int8) Context

Int8 adds the field key with i as a int8 to the logger context.

func (Context) Interface Uses

func (c Context) Interface(key string, i interface{}) Context

Interface adds the field key with obj marshaled using reflection.

Code:

obj := struct {
    Name string `json:"name"`
}{
    Name: "john",
}

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Interface("obj", obj).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","obj":{"name":"john"},"message":"hello world"}

func (Context) Ints Uses

func (c Context) Ints(key string, i []int) Context

Ints adds the field key with i as a []int to the logger context.

func (Context) Ints16 Uses

func (c Context) Ints16(key string, i []int16) Context

Ints16 adds the field key with i as a []int16 to the logger context.

func (Context) Ints32 Uses

func (c Context) Ints32(key string, i []int32) Context

Ints32 adds the field key with i as a []int32 to the logger context.

func (Context) Ints64 Uses

func (c Context) Ints64(key string, i []int64) Context

Ints64 adds the field key with i as a []int64 to the logger context.

func (Context) Ints8 Uses

func (c Context) Ints8(key string, i []int8) Context

Ints8 adds the field key with i as a []int8 to the logger context.

func (Context) Logger Uses

func (c Context) Logger() Logger

Logger returns the logger with the context previously set.

func (Context) MACAddr Uses

func (c Context) MACAddr(key string, ha net.HardwareAddr) Context

MACAddr adds MAC address to the context

func (Context) Object Uses

func (c Context) Object(key string, obj LogObjectMarshaler) Context

Object marshals an object that implement the LogObjectMarshaler interface.

Code:

// User implements zerolog.LogObjectMarshaler
u := User{"John", 35, time.Time{}}

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Object("user", u).
    Logger()

log.Log().Msg("hello world")

Output:

{"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}

func (Context) RawJSON Uses

func (c Context) RawJSON(key string, b []byte) Context

RawJSON adds already encoded JSON to context.

No sanity check is performed on b; it must not contain carriage returns and be valid JSON.

func (Context) Stack Uses

func (c Context) Stack() Context

Stack enables stack trace printing for the error passed to Err().

func (Context) Str Uses

func (c Context) Str(key, val string) Context

Str adds the field key with val as a string to the logger context.

func (Context) Strs Uses

func (c Context) Strs(key string, vals []string) Context

Strs adds the field key with val as a string to the logger context.

func (Context) Time Uses

func (c Context) Time(key string, t time.Time) Context

Time adds the field key with t formated as string using zerolog.TimeFieldFormat.

func (Context) Times Uses

func (c Context) Times(key string, t []time.Time) Context

Times adds the field key with t formated as string using zerolog.TimeFieldFormat.

func (Context) Timestamp Uses

func (c Context) Timestamp() Context

Timestamp adds the current local time as UNIX timestamp to the logger context with the "time" key. To customize the key name, change zerolog.TimestampFieldName.

NOTE: It won't dedupe the "time" key if the *Context has one already.

func (Context) Uint Uses

func (c Context) Uint(key string, i uint) Context

Uint adds the field key with i as a uint to the logger context.

func (Context) Uint16 Uses

func (c Context) Uint16(key string, i uint16) Context

Uint16 adds the field key with i as a uint16 to the logger context.

func (Context) Uint32 Uses

func (c Context) Uint32(key string, i uint32) Context

Uint32 adds the field key with i as a uint32 to the logger context.

func (Context) Uint64 Uses

func (c Context) Uint64(key string, i uint64) Context

Uint64 adds the field key with i as a uint64 to the logger context.

func (Context) Uint8 Uses

func (c Context) Uint8(key string, i uint8) Context

Uint8 adds the field key with i as a uint8 to the logger context.

func (Context) Uints Uses

func (c Context) Uints(key string, i []uint) Context

Uints adds the field key with i as a []uint to the logger context.

func (Context) Uints16 Uses

func (c Context) Uints16(key string, i []uint16) Context

Uints16 adds the field key with i as a []uint16 to the logger context.

func (Context) Uints32 Uses

func (c Context) Uints32(key string, i []uint32) Context

Uints32 adds the field key with i as a []uint32 to the logger context.

func (Context) Uints64 Uses

func (c Context) Uints64(key string, i []uint64) Context

Uints64 adds the field key with i as a []uint64 to the logger context.

func (Context) Uints8 Uses

func (c Context) Uints8(key string, i []uint8) Context

Uints8 adds the field key with i as a []uint8 to the logger context.

type Event Uses

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

Event represents a log event. It is instanced by one of the level method of Logger and finalized by the Msg or Msgf method.

func Dict Uses

func Dict() *Event

Dict creates an Event to be used with the *Event.Dict method. Call usual field methods like Str, Int etc to add fields to this event and give it as argument the *Event.Dict method.

func (*Event) AnErr Uses

func (e *Event) AnErr(key string, err error) *Event

AnErr adds the field key with serialized err to the *Event context. If err is nil, no field is added.

func (*Event) Array Uses

func (e *Event) Array(key string, arr LogArrayMarshaler) *Event

Array adds the field key with an array to the event context. Use zerolog.Arr() to create the array or pass a type that implement the LogArrayMarshaler interface.

Code:

log := zerolog.New(os.Stdout)

log.Log().
    Str("foo", "bar").
    Array("array", zerolog.Arr().
        Str("baz").
        Int(1),
    ).
    Msg("hello world")

Output:

{"foo":"bar","array":["baz",1],"message":"hello world"}

Code:

log := zerolog.New(os.Stdout)

// Users implements zerolog.LogArrayMarshaler
u := Users{
    User{"John", 35, time.Time{}},
    User{"Bob", 55, time.Time{}},
}

log.Log().
    Str("foo", "bar").
    Array("users", u).
    Msg("hello world")

Output:

{"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}

func (*Event) Bool Uses

func (e *Event) Bool(key string, b bool) *Event

Bool adds the field key with val as a bool to the *Event context.

func (*Event) Bools Uses

func (e *Event) Bools(key string, b []bool) *Event

Bools adds the field key with val as a []bool to the *Event context.

func (*Event) Bytes Uses

func (e *Event) Bytes(key string, val []byte) *Event

Bytes adds the field key with val as a string to the *Event context.

Runes outside of normal ASCII ranges will be hex-encoded in the resulting JSON.

func (*Event) Caller Uses

func (e *Event) Caller() *Event

Caller adds the file:line of the caller with the zerolog.CallerFieldName key.

func (*Event) Dict Uses

func (e *Event) Dict(key string, dict *Event) *Event

Dict adds the field key with a dict to the event context. Use zerolog.Dict() to create the dictionary.

Code:

log := zerolog.New(os.Stdout)

log.Log().
    Str("foo", "bar").
    Dict("dict", zerolog.Dict().
        Str("bar", "baz").
        Int("n", 1),
    ).
    Msg("hello world")

Output:

{"foo":"bar","dict":{"bar":"baz","n":1},"message":"hello world"}

func (*Event) Discard Uses

func (e *Event) Discard() *Event

Discard disables the event so Msg(f) won't print it.

func (*Event) Dur Uses

func (e *Event) Dur(key string, d time.Duration) *Event

Dur adds the field key with duration d stored as zerolog.DurationFieldUnit. If zerolog.DurationFieldInteger is true, durations are rendered as integer instead of float.

Code:

d := time.Duration(10 * time.Second)

log := zerolog.New(os.Stdout)

log.Log().
    Str("foo", "bar").
    Dur("dur", d).
    Msg("hello world")

Output:

{"foo":"bar","dur":10000,"message":"hello world"}

func (*Event) Durs Uses

func (e *Event) Durs(key string, d []time.Duration) *Event

Durs adds the field key with duration d stored as zerolog.DurationFieldUnit. If zerolog.DurationFieldInteger is true, durations are rendered as integer instead of float.

Code:

d := []time.Duration{
    time.Duration(10 * time.Second),
    time.Duration(20 * time.Second),
}

log := zerolog.New(os.Stdout)

log.Log().
    Str("foo", "bar").
    Durs("durs", d).
    Msg("hello world")

Output:

{"foo":"bar","durs":[10000,20000],"message":"hello world"}

func (*Event) EmbedObject Uses

func (e *Event) EmbedObject(obj LogObjectMarshaler) *Event

Object marshals an object that implement the LogObjectMarshaler interface.

Code:

log := zerolog.New(os.Stdout)

price := Price{val: 6449, prec: 2, unit: "$"}

log.Log().
    Str("foo", "bar").
    EmbedObject(price).
    Msg("hello world")

Output:

{"foo":"bar","price":"$64.49","message":"hello world"}

func (*Event) Enabled Uses

func (e *Event) Enabled() bool

Enabled return false if the *Event is going to be filtered out by log level or sampling.

func (*Event) Err Uses

func (e *Event) Err(err error) *Event

Err adds the field "error" with serialized err to the *Event context. If err is nil, no field is added. To customize the key name, change zerolog.ErrorFieldName.

To customize the key name, change zerolog.ErrorFieldName.

If Stack() has been called before and zerolog.ErrorStackMarshaler is defined, the err is passed to ErrorStackMarshaler and the result is appended to the zerolog.ErrorStackFieldName.

func (*Event) Errs Uses

func (e *Event) Errs(key string, errs []error) *Event

Errs adds the field key with errs as an array of serialized errors to the *Event context.

func (*Event) Fields Uses

func (e *Event) Fields(fields map[string]interface{}) *Event

Fields is a helper function to use a map to set fields using type assertion.

func (*Event) Float32 Uses

func (e *Event) Float32(key string, f float32) *Event

Float32 adds the field key with f as a float32 to the *Event context.

func (*Event) Float64 Uses

func (e *Event) Float64(key string, f float64) *Event

Float64 adds the field key with f as a float64 to the *Event context.

func (*Event) Floats32 Uses

func (e *Event) Floats32(key string, f []float32) *Event

Floats32 adds the field key with f as a []float32 to the *Event context.

func (*Event) Floats64 Uses

func (e *Event) Floats64(key string, f []float64) *Event

Floats64 adds the field key with f as a []float64 to the *Event context.

func (*Event) Hex Uses

func (e *Event) Hex(key string, val []byte) *Event

Hex adds the field key with val as a hex string to the *Event context.

func (*Event) IPAddr Uses

func (e *Event) IPAddr(key string, ip net.IP) *Event

IPAddr adds IPv4 or IPv6 Address to the event

func (*Event) IPPrefix Uses

func (e *Event) IPPrefix(key string, pfx net.IPNet) *Event

IPPrefix adds IPv4 or IPv6 Prefix (address and mask) to the event

func (*Event) Int Uses

func (e *Event) Int(key string, i int) *Event

Int adds the field key with i as a int to the *Event context.

func (*Event) Int16 Uses

func (e *Event) Int16(key string, i int16) *Event

Int16 adds the field key with i as a int16 to the *Event context.

func (*Event) Int32 Uses

func (e *Event) Int32(key string, i int32) *Event

Int32 adds the field key with i as a int32 to the *Event context.

func (*Event) Int64 Uses

func (e *Event) Int64(key string, i int64) *Event

Int64 adds the field key with i as a int64 to the *Event context.

func (*Event) Int8 Uses

func (e *Event) Int8(key string, i int8) *Event

Int8 adds the field key with i as a int8 to the *Event context.

func (*Event) Interface Uses

func (e *Event) Interface(key string, i interface{}) *Event

Interface adds the field key with i marshaled using reflection.

Code:

log := zerolog.New(os.Stdout)

obj := struct {
    Name string `json:"name"`
}{
    Name: "john",
}

log.Log().
    Str("foo", "bar").
    Interface("obj", obj).
    Msg("hello world")

Output:

{"foo":"bar","obj":{"name":"john"},"message":"hello world"}

func (*Event) Ints Uses

func (e *Event) Ints(key string, i []int) *Event

Ints adds the field key with i as a []int to the *Event context.

func (*Event) Ints16 Uses

func (e *Event) Ints16(key string, i []int16) *Event

Ints16 adds the field key with i as a []int16 to the *Event context.

func (*Event) Ints32 Uses

func (e *Event) Ints32(key string, i []int32) *Event

Ints32 adds the field key with i as a []int32 to the *Event context.

func (*Event) Ints64 Uses

func (e *Event) Ints64(key string, i []int64) *Event

Ints64 adds the field key with i as a []int64 to the *Event context.

func (*Event) Ints8 Uses

func (e *Event) Ints8(key string, i []int8) *Event

Ints8 adds the field key with i as a []int8 to the *Event context.

func (*Event) MACAddr Uses

func (e *Event) MACAddr(key string, ha net.HardwareAddr) *Event

MACAddr adds MAC address to the event

func (*Event) Msg Uses

func (e *Event) Msg(msg string)

Msg sends the *Event with msg added as the message field if not empty.

NOTICE: once this method is called, the *Event should be disposed. Calling Msg twice can have unexpected result.

func (*Event) Msgf Uses

func (e *Event) Msgf(format string, v ...interface{})

Msgf sends the event with formated msg added as the message field if not empty.

NOTICE: once this methid is called, the *Event should be disposed. Calling Msg twice can have unexpected result.

func (*Event) Object Uses

func (e *Event) Object(key string, obj LogObjectMarshaler) *Event

Object marshals an object that implement the LogObjectMarshaler interface.

Code:

log := zerolog.New(os.Stdout)

// User implements zerolog.LogObjectMarshaler
u := User{"John", 35, time.Time{}}

log.Log().
    Str("foo", "bar").
    Object("user", u).
    Msg("hello world")

Output:

{"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}

func (*Event) RawJSON Uses

func (e *Event) RawJSON(key string, b []byte) *Event

RawJSON adds already encoded JSON to the log line under key.

No sanity check is performed on b; it must not contain carriage returns and be valid JSON.

func (*Event) Send Uses

func (e *Event) Send()

Send just like call Msg("")

NOTICE: once this method is called, the *Event should be disposed.

func (*Event) Stack Uses

func (e *Event) Stack() *Event

Stack enables stack trace printing for the error passed to Err().

ErrorStackMarshaler must be set for this method to do something.

func (*Event) Str Uses

func (e *Event) Str(key, val string) *Event

Str adds the field key with val as a string to the *Event context.

func (*Event) Strs Uses

func (e *Event) Strs(key string, vals []string) *Event

Strs adds the field key with vals as a []string to the *Event context.

func (*Event) Time Uses

func (e *Event) Time(key string, t time.Time) *Event

Time adds the field key with t formated as string using zerolog.TimeFieldFormat.

func (*Event) TimeDiff Uses

func (e *Event) TimeDiff(key string, t time.Time, start time.Time) *Event

TimeDiff adds the field key with positive duration between time t and start. If time t is not greater than start, duration will be 0. Duration format follows the same principle as Dur().

func (*Event) Times Uses

func (e *Event) Times(key string, t []time.Time) *Event

Times adds the field key with t formated as string using zerolog.TimeFieldFormat.

func (*Event) Timestamp Uses

func (e *Event) Timestamp() *Event

Timestamp adds the current local time as UNIX timestamp to the *Event context with the "time" key. To customize the key name, change zerolog.TimestampFieldName.

NOTE: It won't dedupe the "time" key if the *Event (or *Context) has one already.

func (*Event) Uint Uses

func (e *Event) Uint(key string, i uint) *Event

Uint adds the field key with i as a uint to the *Event context.

func (*Event) Uint16 Uses

func (e *Event) Uint16(key string, i uint16) *Event

Uint16 adds the field key with i as a uint16 to the *Event context.

func (*Event) Uint32 Uses

func (e *Event) Uint32(key string, i uint32) *Event

Uint32 adds the field key with i as a uint32 to the *Event context.

func (*Event) Uint64 Uses

func (e *Event) Uint64(key string, i uint64) *Event

Uint64 adds the field key with i as a uint64 to the *Event context.

func (*Event) Uint8 Uses

func (e *Event) Uint8(key string, i uint8) *Event

Uint8 adds the field key with i as a uint8 to the *Event context.

func (*Event) Uints Uses

func (e *Event) Uints(key string, i []uint) *Event

Uints adds the field key with i as a []int to the *Event context.

func (*Event) Uints16 Uses

func (e *Event) Uints16(key string, i []uint16) *Event

Uints16 adds the field key with i as a []int16 to the *Event context.

func (*Event) Uints32 Uses

func (e *Event) Uints32(key string, i []uint32) *Event

Uints32 adds the field key with i as a []int32 to the *Event context.

func (*Event) Uints64 Uses

func (e *Event) Uints64(key string, i []uint64) *Event

Uints64 adds the field key with i as a []int64 to the *Event context.

func (*Event) Uints8 Uses

func (e *Event) Uints8(key string, i []uint8) *Event

Uints8 adds the field key with i as a []int8 to the *Event context.

type Formatter Uses

type Formatter func(interface{}) string

Formatter transforms the input into a formatted string.

type Hook Uses

type Hook interface {
    // Run runs the hook with the event.
    Run(e *Event, level Level, message string)
}

Hook defines an interface to a log hook.

type HookFunc Uses

type HookFunc func(e *Event, level Level, message string)

HookFunc is an adaptor to allow the use of an ordinary function as a Hook.

func (HookFunc) Run Uses

func (h HookFunc) Run(e *Event, level Level, message string)

Run implements the Hook interface.

type Level Uses

type Level uint8

Level defines log levels.

const (
    // DebugLevel defines debug log level.
    DebugLevel Level = iota
    // InfoLevel defines info log level.
    InfoLevel
    // WarnLevel defines warn log level.
    WarnLevel
    // ErrorLevel defines error log level.
    ErrorLevel
    // FatalLevel defines fatal log level.
    FatalLevel
    // PanicLevel defines panic log level.
    PanicLevel
    // NoLevel defines an absent log level.
    NoLevel
    // Disabled disables the logger.
    Disabled
)

func GlobalLevel Uses

func GlobalLevel() Level

GlobalLevel returns the current global log level

func ParseLevel Uses

func ParseLevel(levelStr string) (Level, error)

ParseLevel converts a level string into a zerolog Level value. returns an error if the input string does not match known values.

func (Level) String Uses

func (l Level) String() string

type LevelHook Uses

type LevelHook struct {
    NoLevelHook, DebugHook, InfoHook, WarnHook, ErrorHook, FatalHook, PanicHook Hook
}

LevelHook applies a different hook for each level.

func NewLevelHook Uses

func NewLevelHook() LevelHook

NewLevelHook returns a new LevelHook.

func (LevelHook) Run Uses

func (h LevelHook) Run(e *Event, level Level, message string)

Run implements the Hook interface.

type LevelSampler Uses

type LevelSampler struct {
    DebugSampler, InfoSampler, WarnSampler, ErrorSampler Sampler
}

LevelSampler applies a different sampler for each level.

func (LevelSampler) Sample Uses

func (s LevelSampler) Sample(lvl Level) bool

type LevelWriter Uses

type LevelWriter interface {
    io.Writer
    WriteLevel(level Level, p []byte) (n int, err error)
}

LevelWriter defines as interface a writer may implement in order to receive level information with payload.

func MultiLevelWriter Uses

func MultiLevelWriter(writers ...io.Writer) LevelWriter

MultiLevelWriter creates a writer that duplicates its writes to all the provided writers, similar to the Unix tee(1) command. If some writers implement LevelWriter, their WriteLevel method will be used instead of Write.

func SyslogLevelWriter Uses

func SyslogLevelWriter(w SyslogWriter) LevelWriter

SyslogLevelWriter wraps a SyslogWriter and call the right syslog level method matching the zerolog level.

type LogArrayMarshaler Uses

type LogArrayMarshaler interface {
    MarshalZerologArray(a *Array)
}

LogArrayMarshaler provides a strongly-typed and encoding-agnostic interface to be implemented by types used with Event/Context's Array methods.

type LogObjectMarshaler Uses

type LogObjectMarshaler interface {
    MarshalZerologObject(e *Event)
}

LogObjectMarshaler provides a strongly-typed and encoding-agnostic interface to be implemented by types used with Event/Context's Object methods.

type Logger Uses

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

A Logger represents an active logging object that generates lines of JSON output to an io.Writer. Each logging operation makes a single call to the Writer's Write method. There is no guaranty on access serialization to the Writer. If your Writer is not thread safe, you may consider a sync wrapper.

func Ctx Uses

func Ctx(ctx context.Context) *Logger

Ctx returns the Logger associated with the ctx. If no logger is associated, a disabled logger is returned.

func New Uses

func New(w io.Writer) Logger

New creates a root logger with given output writer. If the output writer implements the LevelWriter interface, the WriteLevel method will be called instead of the Write one.

Each logging operation makes a single call to the Writer's Write method. There is no guaranty on access serialization to the Writer. If your Writer is not thread safe, you may consider using sync wrapper.

Code:

log := zerolog.New(os.Stdout)

log.Info().Msg("hello world")

Output:

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

func Nop Uses

func Nop() Logger

Nop returns a disabled logger for which all operation are no-op.

func (*Logger) Debug Uses

func (l *Logger) Debug() *Event

Debug starts a new message with debug level.

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

Code:

log := zerolog.New(os.Stdout)

log.Debug().
    Str("foo", "bar").
    Int("n", 123).
    Msg("hello world")

Output:

{"level":"debug","foo":"bar","n":123,"message":"hello world"}

func (*Logger) Err Uses

func (l *Logger) Err(err error) *Event

Err starts a new message with error level with err as a field if not nil or with info level if err is nil.

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

func (*Logger) Error Uses

func (l *Logger) Error() *Event

Error starts a new message with error level.

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

Code:

log := zerolog.New(os.Stdout)

log.Error().
    Err(errors.New("some error")).
    Msg("error doing something")

Output:

{"level":"error","error":"some error","message":"error doing something"}

func (*Logger) Fatal Uses

func (l *Logger) Fatal() *Event

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

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

func (Logger) GetLevel Uses

func (l Logger) GetLevel() Level

GetLevel returns the current Level of l.

func (Logger) Hook Uses

func (l Logger) Hook(h Hook) Logger

Hook returns a logger with the h Hook.

Code:

var levelNameHook LevelNameHook
var messageHook MessageHook = "The message"

log := zerolog.New(os.Stdout).Hook(levelNameHook).Hook(messageHook)

log.Info().Msg("hello world")

Output:

{"level":"info","level_name":"info","the_message":"hello world","message":"hello world"}

func (*Logger) Info Uses

func (l *Logger) Info() *Event

Info starts a new message with info level.

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

Code:

log := zerolog.New(os.Stdout)

log.Info().
    Str("foo", "bar").
    Int("n", 123).
    Msg("hello world")

Output:

{"level":"info","foo":"bar","n":123,"message":"hello world"}

func (Logger) Level Uses

func (l Logger) Level(lvl Level) Logger

Level creates a child logger with the minimum accepted level set to level.

Code:

log := zerolog.New(os.Stdout).Level(zerolog.WarnLevel)

log.Info().Msg("filtered out message")
log.Error().Msg("kept message")

Output:

{"level":"error","message":"kept message"}

func (*Logger) Log Uses

func (l *Logger) Log() *Event

Log starts a new message with no level. Setting GlobalLevel to Disabled will still disable events produced by this method.

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

Code:

log := zerolog.New(os.Stdout)

log.Log().
    Str("foo", "bar").
    Str("bar", "baz").
    Msg("")

Output:

{"foo":"bar","bar":"baz"}

func (Logger) Output Uses

func (l Logger) Output(w io.Writer) Logger

Output duplicates the current logger and sets w as its output.

func (*Logger) Panic Uses

func (l *Logger) Panic() *Event

Panic starts a new message with panic level. The panic() function is called by the Msg method, which stops the ordinary flow of a goroutine.

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

func (*Logger) Print Uses

func (l *Logger) Print(v ...interface{})

Print sends a log event using debug level and no extra field. Arguments are handled in the manner of fmt.Print.

Code:

log := zerolog.New(os.Stdout)

log.Print("hello world")

Output:

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

func (*Logger) Printf Uses

func (l *Logger) Printf(format string, v ...interface{})

Printf sends a log event using debug level and no extra field. Arguments are handled in the manner of fmt.Printf.

Code:

log := zerolog.New(os.Stdout)

log.Printf("hello %s", "world")

Output:

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

func (Logger) Sample Uses

func (l Logger) Sample(s Sampler) Logger

Sample returns a logger with the s sampler.

Code:

log := zerolog.New(os.Stdout).Sample(&zerolog.BasicSampler{N: 2})

log.Info().Msg("message 1")
log.Info().Msg("message 2")
log.Info().Msg("message 3")
log.Info().Msg("message 4")

Output:

{"level":"info","message":"message 1"}
{"level":"info","message":"message 3"}

func (*Logger) UpdateContext Uses

func (l *Logger) UpdateContext(update func(c Context) Context)

UpdateContext updates the internal logger's context.

Use this method with caution. If unsure, prefer the With method.

func (*Logger) Warn Uses

func (l *Logger) Warn() *Event

Warn starts a new message with warn level.

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

Code:

log := zerolog.New(os.Stdout)

log.Warn().
    Str("foo", "bar").
    Msg("a warning message")

Output:

{"level":"warn","foo":"bar","message":"a warning message"}

func (Logger) With Uses

func (l Logger) With() Context

With creates a child logger with the field added to its context.

Code:

log := zerolog.New(os.Stdout).
    With().
    Str("foo", "bar").
    Logger()

log.Info().Msg("hello world")

Output:

{"level":"info","foo":"bar","message":"hello world"}

func (*Logger) WithContext Uses

func (l *Logger) WithContext(ctx context.Context) context.Context

WithContext returns a copy of ctx with l associated. If an instance of Logger is already in the context, the context is not updated.

For instance, to add a field to an existing logger in the context, use this notation:

ctx := r.Context()
l := zerolog.Ctx(ctx)
l.UpdateContext(func(c Context) Context {
    return c.Str("bar", "baz")
})

func (*Logger) WithLevel Uses

func (l *Logger) WithLevel(level Level) *Event

WithLevel starts a new message with level. Unlike Fatal and Panic methods, WithLevel does not terminate the program or stop the ordinary flow of a gourotine when used with their respective levels.

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

Code:

log := zerolog.New(os.Stdout)

log.WithLevel(zerolog.InfoLevel).
    Msg("hello world")

Output:

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

func (Logger) Write Uses

func (l Logger) Write(p []byte) (n int, err error)

Write implements the io.Writer interface. This is useful to set as a writer for the standard library log.

Code:

log := zerolog.New(os.Stdout).With().
    Str("foo", "bar").
    Logger()

stdlog.SetFlags(0)
stdlog.SetOutput(log)

stdlog.Print("hello world")

Output:

{"foo":"bar","message":"hello world"}

type RandomSampler Uses

type RandomSampler uint32

RandomSampler use a PRNG to randomly sample an event out of N events, regardless of their level.

func (RandomSampler) Sample Uses

func (s RandomSampler) Sample(lvl Level) bool

Sample implements the Sampler interface.

type Sampler Uses

type Sampler interface {
    // Sample returns true if the event should be part of the sample, false if
    // the event should be dropped.
    Sample(lvl Level) bool
}

Sampler defines an interface to a log sampler.

type SyslogWriter Uses

type SyslogWriter interface {
    io.Writer
    Debug(m string) error
    Info(m string) error
    Warning(m string) error
    Err(m string) error
    Emerg(m string) error
    Crit(m string) error
}

SyslogWriter is an interface matching a syslog.Writer struct.

Directories

PathSynopsis
diodePackage diode provides a thread-safe, lock-free, non-blocking io.Writer wrapper.
diode/internal/diodes
hlogPackage hlog provides a set of http.Handler helpers for zerolog.
internal/cborPackage cbor provides primitives for storing different data in the CBOR (binary) format.
internal/cbor/examples
internal/json
journald
logPackage log provides a global logger for zerolog.
pkgerrors

Package zerolog imports 18 packages (graph) and is imported by 373 packages. Updated 2019-07-04. Refresh now. Tools for package owners.