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A Simple Go Logger

A simplified log library with support for logging to console (stderr), file, and syslog. It supports three log levels: debug, info, and error.

Build Status

Usage

In its simplest form log will output use the info log level and output messages to the console. For example:

logger := log.New()
logger.Info("Hello, world!")

It may be configured to log elsewhere by configuring it with a target:

target := log.NewTargetOpt("file:///var/log/example.log")
logger := log.New(target)
logger.Info("Hello, world!")

By default a logger has its level set to info which will log info and error messages. To change the level:

level := log.NewLevelOpt("debug")
logger := log.New(level)
logger.Debug("Too much information here.")

You can combine the two:

target := log.SyslogOpt
level := log.NewLevelOpt("error")
logger := log.New(target, level)
logger.Error("Oops! Something went wrong.")

The log.SyslogOpt value is a target which points to the local syslog server.

The library's Writer implements io.Writer and can be used to write logs at a specific level:

wrt := log.NewWriter(log.LevelDebug, logger)
wrt.Write(data)

Targets

The NewTargetOpt function takes the URI (as a string) of a file or network socket to log to. If the file is a socket it is assumed to be attached to a running syslog server. Network sockets assume the same. The special values "syslog", "stderr", and "stdout" will cause the target to log to syslog, stderr, and stdout respectively. The log.SyslogOpt and log.ConsoleOpt values are shortcuts to calling log.NewTargetOpt("syslog") and log.NewTargetOpt("stderr").

Levels

The NewLevelOpt function takes the log level (as as string) as its only argument. Case is ignored. Valid levels are "debug", "info", and "error". Log messages at or greater than that level will be logged. The special values log.Debug, log.Info, and log.Error are equivelent to log.NewLevelOpt("debug"), log.NewLevelOpt("info"), and log.NewLevelOpt("error").

Logging

The following methods log to the logger:

  • Print: Log a message at the provided level.
  • Printf: Log a formatted message at the provided level.
  • Panic: Log a message at the error level and call panic().
  • Panicf: Log a formatted message at the error level and call panic().
  • Fatal: Log a message at the error level and call os.Exit(1).
  • Fatalf: Log a formatted message at the error level and call os.Exit(1).
  • Debug: Log a message at the debug level.
  • Debugf: Log a formatted message at the debug level.
  • Info: Log a message at the info level.
  • Infof: Log a formatted message at the info level.
  • Error: Log a message at the error level.
  • Errorf: Log a formatted message at the error level.

License

Copyright (c) 2014 Ryan Bourgeois. Licensed under BSD-Modified. See the LICENSE file for a copy of the license.