logs

Documentation

Overview

Package logs defines an interface and default implementation for subsystem logging.

Log level verbosity may be modified at runtime for each individual subsystem logger.

The default implementation in this package must be created by the Backend type. Backends can write to any io.Writer, including multi-writers created by io.MultiWriter. Multi-writers allow log output to be written to many writers, including standard output and log files.

Optional logging behavior can be specified by using the LOGFLAGS environment variable and overridden per-Backend by using the WithFlags call option. Multiple LOGFLAGS options can be specified, separated by commas. The following options are recognized:

longfile: Include the full filepath and line number in all log messages

shortfile: Include the filename and line number in all log messages.
Overrides longfile.

Index

• Constants
• type Backend
  • func NewBackend(opts ...BackendOption) *Backend
  • func (b *Backend) AddLogFile(logFile string, logLevel Level) error
  • func (b *Backend) AddLogFileWithCustomRotator(logFile string, logLevel Level, thresholdKB int64, maxRolls int) error
  • func (b *Backend) Close()
  • func (b *Backend) Logger(subsystemTag string) *Logger
• type BackendOption
  • func WithFlags(flags uint32) BackendOption
• type Level
  • func LevelFromString(s string) (l Level, ok bool)
  • func (l Level) String() string
• type Logger
  • func (l *Logger) Backend() *Backend
  • func (l *Logger) Critical(args ...interface{})
  • func (l *Logger) Criticalf(format string, args ...interface{})
  • func (l *Logger) Debug(args ...interface{})
  • func (l *Logger) Debugf(format string, args ...interface{})
  • func (l *Logger) Error(args ...interface{})
  • func (l *Logger) Errorf(format string, args ...interface{})
  • func (l *Logger) Info(args ...interface{})
  • func (l *Logger) Infof(format string, args ...interface{})
  • func (l *Logger) Level() Level
  • func (l *Logger) SetLevel(level Level)
  • func (l *Logger) Trace(args ...interface{})
  • func (l *Logger) Tracef(format string, args ...interface{})
  • func (l *Logger) Warn(args ...interface{})
  • func (l *Logger) Warnf(format string, args ...interface{})
  • func (l *Logger) Write(logLevel Level, args ...interface{})
  • func (l *Logger) Writef(logLevel Level, format string, args ...interface{})

Constants

const (
	// Llongfile modifies the logger output to include full path and line number
	// of the logging callsite, e.g. /a/b/c/main.go:123.
	Llongfile uint32 = 1 << iota

	// Lshortfile modifies the logger output to include filename and line number
	// of the logging callsite, e.g. main.go:123. Overrides Llongfile.
	Lshortfile
)

Flags to modify Backend's behavior.

Types

type Backend

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

Backend is a logging backend. Subsystems created from the backend write to the backend's Writer. Backend provides atomic writes to the Writer from all subsystems.

func NewBackend

func NewBackend(opts ...BackendOption) *Backend

NewBackend creates a new logger backend.

func (*Backend) AddLogFile

func (b *Backend) AddLogFile(logFile string, logLevel Level) error

AddLogFile adds a file which the log will write into on a certain log level with the default log rotation settings. It'll create the file if it doesn't exist.

func (*Backend) AddLogFileWithCustomRotator

func (b *Backend) AddLogFileWithCustomRotator(logFile string, logLevel Level, thresholdKB int64, maxRolls int) error

AddLogFileWithCustomRotator adds a file which the log will write into on a certain log level, with the specified log rotation settings. It'll create the file if it doesn't exist.

func (*Backend) Close

func (b *Backend) Close()

Close finalizes all log rotators for this backend

func (*Backend) Logger

func (b *Backend) Logger(subsystemTag string) *Logger

Logger returns a new logger for a particular subsystem that writes to the Backend b. A tag describes the subsystem and is included in all log messages. The logger uses the info verbosity level by default.

type BackendOption

type BackendOption func(b *Backend)

BackendOption is a function used to modify the behavior of a Backend.

func WithFlags

func WithFlags(flags uint32) BackendOption

WithFlags configures a Backend to use the specified flags rather than using the package's defaults as determined through the LOGFLAGS environment variable.

type Level

type Level uint32

Level is the level at which a logger is configured. All messages sent to a level which is below the current level are filtered.

const (
	LevelTrace Level = iota
	LevelDebug
	LevelInfo
	LevelWarn
	LevelError
	LevelCritical
	LevelOff
)

Level constants.

func LevelFromString

func LevelFromString(s string) (l Level, ok bool)

LevelFromString returns a level based on the input string s. If the input can't be interpreted as a valid log level, the info level and false is returned.

func (Level) String

func (l Level) String() string

String returns the tag of the logger used in log messages, or "OFF" if the level will not produce any log output.

type Logger

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

Logger is a subsystem logger for a Backend.

func (*Logger) Backend

func (l *Logger) Backend() *Backend

Backend returns the log backend

func (*Logger) Critical

func (l *Logger) Critical(args ...interface{})

Critical formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelCritical.

func (*Logger) Criticalf

func (l *Logger) Criticalf(format string, args ...interface{})

Criticalf formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelCritical.

func (*Logger) Debug

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

Debug formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelDebug.

func (*Logger) Debugf

func (l *Logger) Debugf(format string, args ...interface{})

Debugf formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelDebug.

func (*Logger) Error

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

Error formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelError.

func (*Logger) Errorf

func (l *Logger) Errorf(format string, args ...interface{})

Errorf formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelError.

func (*Logger) Info

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

Info formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelInfo.

func (*Logger) Infof

func (l *Logger) Infof(format string, args ...interface{})

Infof formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelInfo.

func (*Logger) Level

func (l *Logger) Level() Level

Level returns the current logging level

func (*Logger) SetLevel

func (l *Logger) SetLevel(level Level)

SetLevel changes the logging level to the passed level.

func (*Logger) Trace

func (l *Logger) Trace(args ...interface{})

Trace formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelTrace.

func (*Logger) Tracef

func (l *Logger) Tracef(format string, args ...interface{})

Tracef formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelTrace.

func (*Logger) Warn

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

Warn formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with LevelWarn.

func (*Logger) Warnf

func (l *Logger) Warnf(format string, args ...interface{})

Warnf formats message according to format specifier, prepends the prefix as necessary, and writes to log with LevelWarn.

func (*Logger) Write

func (l *Logger) Write(logLevel Level, args ...interface{})

Write formats message using the default formats for its operands, prepends the prefix as necessary, and writes to log with the given logLevel.

func (*Logger) Writef

func (l *Logger) Writef(logLevel Level, format string, args ...interface{})

Writef formats message according to format specifier, prepends the prefix as necessary, and writes to log with the given logLevel.