logger

Documentation

Overview

Package logger defines interfaces that logger drivers implement to log messages.

The other half of a logger driver is the implementation of the factory, which holds the contextual instance information that allows multiple loggers of the same type to perform different actions, such as logging to different locations.

Index

• Constants
• Variables
• func RegisterLogDriver(name string, c Creator) error
• func RegisterLogOptValidator(name string, l LogOptValidator) error
• func ValidateLogOpts(name string, cfg map[string]string) error
• type Context
  • func (ctx *Context) Command() string
  • func (ctx *Context) ExtraAttributes(keyMod func(string) string) map[string]string
  • func (ctx *Context) FullID() string
  • func (ctx *Context) Hostname() (string, error)
  • func (ctx *Context) ID() string
  • func (ctx *Context) ImageFullID() string
  • func (ctx *Context) ImageID() string
  • func (ctx *Context) ImageName() string
  • func (ctx *Context) Name() string
• type Copier
  • func NewCopier(srcs map[string]io.Reader, dst Logger) *Copier
  • func (c *Copier) Close()
  • func (c *Copier) Run()
  • func (c *Copier) Wait()
• type Creator
  • func GetLogDriver(name string) (Creator, error)
• type LogAttributes
  • func (a LogAttributes) String() string
• type LogOptValidator
• type LogReader
• type LogWatcher
  • func NewLogWatcher() *LogWatcher
  • func (w *LogWatcher) Close()
  • func (w *LogWatcher) WatchClose() <-chan struct{}
• type Logger
• type Message
  • func CopyMessage(msg *Message) *Message
• type ReadConfig

Constants

const (
	// TimeFormat is the time format used for timestamps sent to log readers.
	TimeFormat = jsonlog.RFC3339NanoFixed
)

Variables

var ErrReadLogsNotSupported = errors.New("configured logging reader does not support reading")

ErrReadLogsNotSupported is returned when the logger does not support reading logs.

Functions

func RegisterLogDriver

func RegisterLogDriver(name string, c Creator) error

RegisterLogDriver registers the given logging driver builder with given logging driver name.

func RegisterLogOptValidator

func RegisterLogOptValidator(name string, l LogOptValidator) error

RegisterLogOptValidator registers the logging option validator with the given logging driver name.

func ValidateLogOpts

func ValidateLogOpts(name string, cfg map[string]string) error

ValidateLogOpts checks the options for the given log driver. The options supported are specific to the LogDriver implementation.

Types

type Context

type Context struct {
	Config              map[string]string
	ContainerID         string
	ContainerName       string
	ContainerEntrypoint string
	ContainerArgs       []string
	ContainerImageID    string
	ContainerImageName  string
	ContainerCreated    time.Time
	ContainerEnv        []string
	ContainerLabels     map[string]string
	LogPath             string
	DaemonName          string
}

Context provides enough information for a logging driver to do its function.

func (*Context) Command

func (ctx *Context) Command() string

Command returns the command that the container being logged was started with. The Entrypoint is prepended to the container arguments.

func (*Context) ExtraAttributes

func (ctx *Context) ExtraAttributes(keyMod func(string) string) map[string]string

ExtraAttributes returns the user-defined extra attributes (labels, environment variables) in key-value format. This can be used by log drivers that support metadata to add more context to a log.

func (*Context) FullID

func (ctx *Context) FullID() string

FullID is an alias of ContainerID.

func (*Context) Hostname

func (ctx *Context) Hostname() (string, error)

Hostname returns the hostname from the underlying OS.

func (*Context) ID

func (ctx *Context) ID() string

ID Returns the Container ID shortened to 12 characters.

func (*Context) ImageFullID

func (ctx *Context) ImageFullID() string

ImageFullID is an alias of ContainerImageID.

func (*Context) ImageID

func (ctx *Context) ImageID() string

ImageID returns the ContainerImageID shortened to 12 characters.

func (*Context) ImageName

func (ctx *Context) ImageName() string

ImageName is an alias of ContainerImageName

func (*Context) Name

func (ctx *Context) Name() string

Name returns the ContainerName without a preceding '/'.

type Copier

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

Copier can copy logs from specified sources to Logger and attach Timestamp. Writes are concurrent, so you need implement some sync in your logger.

func NewCopier

func NewCopier(srcs map[string]io.Reader, dst Logger) *Copier

NewCopier creates a new Copier

func (*Copier) Close

func (c *Copier) Close()

Close closes the copier

func (*Copier) Run

func (c *Copier) Run()

Run starts logs copying

func (*Copier) Wait

func (c *Copier) Wait()

Wait waits until all copying is done

type Creator

type Creator func(Context) (Logger, error)

Creator builds a logging driver instance with given context.

func GetLogDriver

func GetLogDriver(name string) (Creator, error)

GetLogDriver provides the logging driver builder for a logging driver name.

type LogAttributes

type LogAttributes map[string]string

LogAttributes is used to hold the extra attributes available in the log message Primarily used for converting the map type to string and sorting.

func (LogAttributes) String

func (a LogAttributes) String() string

type LogOptValidator

type LogOptValidator func(cfg map[string]string) error

LogOptValidator checks the options specific to the underlying logging implementation.

type LogReader

type LogReader interface {
	// Read logs from underlying logging backend
	ReadLogs(ReadConfig) *LogWatcher
}

LogReader is the interface for reading log messages for loggers that support reading.

type LogWatcher

type LogWatcher struct {
	// For sending log messages to a reader.
	Msg chan *Message
	// For sending error messages that occur while while reading logs.
	Err chan error
	// contains filtered or unexported fields
}

LogWatcher is used when consuming logs read from the LogReader interface.

func NewLogWatcher

func NewLogWatcher() *LogWatcher

NewLogWatcher returns a new LogWatcher.

func (*LogWatcher) Close

func (w *LogWatcher) Close()

Close notifies the underlying log reader to stop.

func (*LogWatcher) WatchClose

func (w *LogWatcher) WatchClose() <-chan struct{}

WatchClose returns a channel receiver that receives notification when the watcher has been closed. This should only be called from one goroutine.

type Logger

type Logger interface {
	Log(*Message) error
	Name() string
	Close() error
}

Logger is the interface for docker logging drivers.

type Message

type Message struct {
	Line      []byte
	Source    string
	Timestamp time.Time
	Attrs     LogAttributes
	Partial   bool
}

Message is datastructure that represents piece of output produced by some container. The Line member is a slice of an array whose contents can be changed after a log driver's Log() method returns.

func CopyMessage

func CopyMessage(msg *Message) *Message

CopyMessage creates a copy of the passed-in Message which will remain unchanged if the original is changed. Log drivers which buffer Messages rather than dispatching them during their Log() method should use this function to obtain a Message whose Line member's contents won't change.

type ReadConfig

type ReadConfig struct {
	Since  time.Time
	Tail   int
	Follow bool
}

ReadConfig is the configuration passed into ReadLogs.