logrus hooks, and how they work

main.go

package main

import (
	"fmt"
	"io"
	"os"

	"github.com/sirupsen/logrus"
)

type LokiHook struct{}

func (h *LokiHook) Fire(e *logrus.Entry) error {
	fmt.Println("🔥 !!! - " + e.Message)
	return nil
}

func (h *LokiHook) Levels() []logrus.Level {
	return []logrus.Level{
		logrus.DebugLevel,
	}
}

type UsualHook struct {
	Writer io.Writer
}

func (h *UsualHook) Fire(entry *logrus.Entry) error {
	line, err := entry.String()
	if err != nil {
		return err
	}

	_, err = h.Writer.Write([]byte(line))
	return err
}

func (h *UsualHook) Levels() []logrus.Level {
	return []logrus.Level{
		logrus.InfoLevel,
		logrus.WarnLevel,
		logrus.ErrorLevel,
		logrus.FatalLevel,
		logrus.PanicLevel,
	}
}

func main() {
	h := &LokiHook{}
	u := &UsualHook{
		Writer: os.Stdout,
	}

	log := logrus.New()
	log.SetOutput(io.Discard)
	// log.SetFormatter(&logrus.TextFormatter{})
	// log.SetReportCaller(true)
	log.SetLevel(logrus.DebugLevel)

	log.AddHook(h)
	log.AddHook(u)
	log.Info("Hello")
	log.Debug("Hook?")
}