slog: Kafka handler

A Kafka Handler for slog Go library.

See also:

• slog-multi: slog.Handler chaining, fanout, routing, failover, load balancing...
• slog-formatter: slog attribute formatting
• slog-sampling: slog sampling policy
• slog-gin: Gin middleware for slog logger
• slog-echo: Echo middleware for slog logger
• slog-fiber: Fiber middleware for slog logger
• slog-datadog: A slog handler for Datadog
• slog-rollbar: A slog handler for Rollbar
• slog-sentry: A slog handler for Sentry
• slog-syslog: A slog handler for Syslog
• slog-logstash: A slog handler for Logstash
• slog-fluentd: A slog handler for Fluentd
• slog-graylog: A slog handler for Graylog
• slog-loki: A slog handler for Loki
• slog-slack: A slog handler for Slack
• slog-telegram: A slog handler for Telegram
• slog-mattermost: A slog handler for Mattermost
• slog-microsoft-teams: A slog handler for Microsoft Teams
• slog-webhook: A slog handler for Webhook
• slog-kafka: A slog handler for Kafka

🚀 Install

go get github.com/samber/slog-kafka

Compatibility: go >= 1.21

No breaking changes will be made to exported APIs before v2.0.0.

💡 Usage

GoDoc: https://pkg.go.dev/github.com/samber/slog-kafka

Handler options

type Option struct {
    // log level (default: debug)
	Level     slog.Leveler

	// Kafka Writer
	KafkaWriter *kafka.Writer

	// optional: customize Kafka event builder
	Converter Converter
}

Supported attributes

The following attributes are interpreted by slogkafka.DefaultConverter:

Atribute name	slog.Kind	Underlying type
"user"	group (see below)
"error"	any	error
"request"	any	*http.Request
other attributes	*

Other attributes will be injected in extra field.

Users must be of type slog.Group. Eg:

slog.Group("user",
    slog.String("id", "user-123"),
    slog.String("username", "samber"),
    slog.Time("created_at", time.Now()),
)

Example

import (
	"context"
	"fmt"
	"time"

	slogkafka "github.com/samber/slog-kafka"
	"github.com/segmentio/kafka-go"

	"log/slog"
)

func main() {
	// docker-compose up -d

	uri := "127.0.0.1:9092"

	dialer := &kafka.Dialer{
		Timeout:   10 * time.Second,
		DualStack: true,
	}

	conn, err := dialer.DialContext(context.Background(), "tcp", uri)
	if err != nil {
		panic(err)
	}

	err = conn.CreateTopics(kafka.TopicConfig{
		Topic:             "logs",
		NumPartitions:     12,
		ReplicationFactor: 1,
	})
	if err != nil {
		panic(err)
	}

	writer := kafka.NewWriter(kafka.WriterConfig{
		Brokers: []string{uri},
		Topic:   "logs",
		Dialer:  dialer,

		Async:       true,
		Balancer:    &kafka.Hash{},
		MaxAttempts: 3,

		Logger: kafka.LoggerFunc(func(msg string, args ...interface{}) {
			fmt.Printf(msg+"\n", args...)
		}),
		ErrorLogger: kafka.LoggerFunc(func(msg string, args ...interface{}) {
			fmt.Printf(msg+"\n", args...)
		}),
	})

	defer writer.Close()
	defer conn.Close()

	logger := slog.New(slogkafka.Option{Level: slog.LevelDebug, KafkaWriter: writer}.NewKafkaHandler())
	logger = logger.With("release", "v1.0.0")

	logger.
		With(
			slog.Group("user",
				slog.String("id", "user-123"),
				slog.Time("created_at", time.Now()),
			),
		).
		With("error", fmt.Errorf("an error")).
		Error("a message")
}

Kafka message:

{
  "level": "ERROR",
	"logger": "samber/slog-kafka",
	"message": "a message",
	"timestamp": "2023-04-30T01:33:21.676768Z",
	"error": {
		"error": "an error",
		"kind": "*errors.errorString",
		"stack": null
	},
	"extra": {
		"release": "v1.0.0"
	},
	"user": {
		"created_at": "2023-04-30T01:33:21.676704Z",
		"id": "user-123"
	}
}

🤝 Contributing

• Ping me on twitter @samuelberthe (DMs, mentions, whatever :))
• Fork the project
• Fix open issues or request new features

Don't hesitate ;)

# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test

👤 Contributors

💫 Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2023 Samuel Berthe.

This project is MIT licensed.