structlog

README

structlog

Package structlog provides a simple structured logging facade.

Documentation

Overview

Package structlog provides a simple structured logging facade.

Index

• type Logger
  • func StdLogger(calldepth int) Logger
• type LoggerFunc
  • func (f LoggerFunc) Log(keyvals ...interface{}) error

Examples

• StdLogger

Types

type Logger

type Logger interface {
	Log(keyvals ...interface{}) error
}

Logger is the fundamental interface for all log operations. Log creates a log event from keyvals, a variadic sequence of alternating keys and values. Implementations must be safe for concurrent use by multiple goroutines. In particular, any implementation of Logger that appends to keyvals or modifies any of its elements must make a copy first.

This interface (and its description) has been copied from go-kit (https://github.com/go-kit/kit/blob/master/log/log.go). Note that application logging callers are not expected to check for errors, see https://github.com/go-kit/kit/issues/164.

var DefaultLogger Logger = StdLogger(1)

DefaultLogger provides a default logger. The default implementation uses the Go standard library logger. To override, set this variable early in the program initialization.

func StdLogger

func StdLogger(calldepth int) Logger

StdLogger returns a logger that logs to the standard logger. Calldepth is the count of the number of frames to skip when computing the file name and line number if Llongfile or Lshortfile is set; a value of 1 will print the details for the caller of Log.

Example

log.SetOutput(os.Stdout)
log.SetFlags(log.Lshortfile)

logger := StdLogger(1)
logger.Log("msg", "the message")
logger.Log("msg", "the message", "p1", 1, "lvl", "error")
logger.Log("msg", "the message", "p1", 1, "lvl", "warn", "p2", "param 2")
logger.Log("msg", "the message", "p1", os.Stderr, "p2", 2)
logger.Log("msg", stringer{})
logger.Log("msg", 123)

Output:

structlog_test.go:15: the message
structlog_test.go:16: error: the message: p1=1
structlog_test.go:17: warn: the message: p1=1 p2="param 2"
structlog_test.go:18: the message: p1="unsupported value type" p2=2
structlog_test.go:19: I'M A STRING
structlog_test.go:20: 123

type LoggerFunc

type LoggerFunc func(...interface{}) error

LoggerFunc is an adapter to allow use of ordinary functions as Loggers. If f is a function with the appropriate signature, LoggerFunc(f) is a Logger object that calls f.

func (LoggerFunc) Log

func (f LoggerFunc) Log(keyvals ...interface{}) error

Log implements Logger by calling f(keyvals...).