metalog

README

metalog

Metalog is a logging interface with as few dependencies as possible.

logrus is a great tool, but with one flaw: it doesn't have a "pure interface"

example: the FieldLogger: https://godoc.org/github.com/sirupsen/logrus#FieldLogger

type FieldLogger interface {
    WithField(key string, value interface{}) *logrus.Entry
    WithFields(fields logrus.Fields) *logrus.Entry
    ...
}

this interface is tied to the logrus package via logrus.Entry and logrus.Fields, so if you want to accept that interface in your library you end up with a dependency on the logrus package. That kinda defeats the point of having an interface.

Fortunately this problem can be easily solved:

• logrus.Fields is just a map[string]interface{}
• logrus.Entry is just a logrus.FieldLogger

so it's pretty trivial to create a thin compatibility layer over logrus in order to reach this interface:

type FieldLogger interface {
	WithField(string, interface{}) Logger
	WithFields(map[string]interface{}) Logger
}

This interface allows your library to accept a Logger without having a dependency directly on logrus.

Clients that want to use your library can just wrap logrus with this client that's so tiny I can paste it here

type Logger struct {
	logrus.FieldLogger
}

func (l *Logger) WithField(field string, value interface{}) FieldLogger {
	return &Logger{
		FieldLogger: l.FieldLogger.WithField(field, value),
	}
}

func (l *Logger) WithFields(fields map[string]interface{}) FieldLogger {
	return &Logger{
		FieldLogger: l.FieldLogger.WithFields(fields),
	}
}

Of course you can use directly the metalogrus package for convenience

Documentation

Overview

package metalog implements a logging interface that's similar to logrus but doesn't actually depends on the logrus package

Index

• type Logger

Types

type Logger

type Logger interface {
	Debug(args ...interface{})
	Info(args ...interface{})
	Error(args ...interface{})
	Fatal(args ...interface{})
	WithField(string, interface{}) Logger
	WithFields(map[string]interface{}) Logger
}

Logger is a logging interface that allows to write to the 4 most common levels and to add fields to the logger