logutils

README

logutils

logutils is a Go package that augments the standard library "log" package to make logging a bit more modern, without fragmenting the Go ecosystem with new logging packages.

The simplest thing that could possibly work

Presumably your application already uses the default log package. To switch, you'll want your code to look like the following:

package main

import (
	"log"
	"os"

	"github.com/capcom6/logutils"
)

func main() {
	filter := &logutils.LevelFilter{
		Levels: []logutils.LogLevel{"DEBUG", "WARN", "ERROR"},
		MinLevel: logutils.LogLevel("WARN"),
		Writer: os.Stderr,
	}
	log.SetOutput(filter)

	log.Print("[DEBUG] Debugging") // this will not print
	log.Print("[WARN] Warning") // this will
	log.Print("[ERROR] Erring") // and so will this
	log.Print("Message I haven't updated") // and so will this
}

This logs to standard error exactly like go's standard logger. Any log messages you haven't converted to have a level will continue to print as before.

Default filter

You can also use the default filter named DefaultLevelFilter as follows:

package main

import (
	"log"

	"github.com/capcom6/logutils"
)

func main() {
	log.SetOutput(logutils.DefaultLevelFilter)

	logutils.Debug("Debugging") // this will not print
	logutils.Warn("Warning") // this will
	logutils.Error("Erring") // and so will this
	logutils.Print("Message I haven't updated") // and so will this
}

Documentation

Overview

Package logutils augments the standard log package with levels.

Index

• Variables
• func Debug(v ...any)
• func Debugf(format string, v ...any)
• func Debugln(v ...any)
• func Error(v ...any)
• func Errorf(format string, v ...any)
• func Errorln(v ...any)
• func Fatal(v ...any)
• func Fatalf(format string, v ...any)
• func Fatalln(v ...any)
• func Print(v ...any)
• func Printf(format string, v ...any)
• func Println(v ...any)
• func Warn(v ...any)
• func Warnf(format string, v ...any)
• func Warnln(v ...any)
• type LevelFilter
  • func (f *LevelFilter) Check(line []byte) bool
  • func (f *LevelFilter) SetMinLevel(min LogLevel)
  • func (f *LevelFilter) Write(p []byte) (n int, err error)
• type LogLevel

Variables

var DefaultLevelFilter = &LevelFilter{
	Levels:   []LogLevel{"TRACE", "DEBUG", "INFO", "WARN", "ERROR"},
	MinLevel: "WARN",
	Writer:   os.Stdout,
}

Functions

func Debug

func Debug(v ...any)

func Debugf

func Debugf(format string, v ...any)

func Debugln

func Debugln(v ...any)

func Error

func Error(v ...any)

func Errorf

func Errorf(format string, v ...any)

func Errorln

func Errorln(v ...any)

func Fatal

func Fatal(v ...any)

func Fatalf

func Fatalf(format string, v ...any)

func Fatalln

func Fatalln(v ...any)

func Print

func Print(v ...any)

func Printf

func Printf(format string, v ...any)

func Println

func Println(v ...any)

func Warn

func Warn(v ...any)

func Warnf

func Warnf(format string, v ...any)

func Warnln

func Warnln(v ...any)

Types

type LevelFilter

type LevelFilter struct {
	// Levels is the list of log levels, in increasing order of
	// severity. Example might be: {"DEBUG", "WARN", "ERROR"}.
	Levels []LogLevel

	// MinLevel is the minimum level allowed through
	MinLevel LogLevel

	// The underlying io.Writer where log messages that pass the filter
	// will be set.
	Writer io.Writer
	// contains filtered or unexported fields
}

LevelFilter is an io.Writer that can be used with a logger that will filter out log messages that aren't at least a certain level.

Once the filter is in use somewhere, it is not safe to modify the structure.

func (*LevelFilter) Check

func (f *LevelFilter) Check(line []byte) bool

Check will check a given line if it would be included in the level filter.

func (*LevelFilter) SetMinLevel

func (f *LevelFilter) SetMinLevel(min LogLevel)

SetMinLevel is used to update the minimum log level

func (*LevelFilter) Write

func (f *LevelFilter) Write(p []byte) (n int, err error)

type LogLevel

type LogLevel string