slog: Betterstack handler

A Betterstack Handler for slog Go library.

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See also:

• slog-multi: slog.Handler chaining, fanout, routing, failover, load balancing...
• slog-formatter: slog attribute formatting
• slog-sampling: slog sampling policy
• slog-mock: slog.Handler for test purposes

HTTP middlewares:

• slog-gin: Gin middleware for slog logger
• slog-echo: Echo middleware for slog logger
• slog-fiber: Fiber middleware for slog logger
• slog-chi: Chi middleware for slog logger
• slog-http: net/http middleware for slog logger

Loggers:

• slog-zap: A slog handler for Zap
• slog-zerolog: A slog handler for Zerolog
• slog-logrus: A slog handler for Logrus

Log sinks:

• slog-datadog: A slog handler for Datadog
• slog-betterstack: A slog handler for Betterstack
• slog-rollbar: A slog handler for Rollbar
• slog-loki: A slog handler for Loki
• 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-quickwit: A slog handler for Quickwit
• 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
• slog-nats: A slog handler for NATS
• slog-parquet: A slog handler for Parquet + Object Storage
• slog-channel: A slog handler for Go channels

🚀 Install

go get github.com/samber/slog-betterstack

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-betterstack

Handler options

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

  // token
  Token   string
  // optional: endpoint
  Endpoint string
  // default: 10s
  Timeout time.Duration

  // optional: minimum delay after the last record before a batch is sent (default: 1s)
  MinBatchWait time.Duration
  // optional: maximum time a record can be buffered before being sent (default: 3s)
  MaxBatchWait time.Duration
  // optional: maximum number of records in a batch (default: 1000)
  MaxBatchSize int
  // optional: maximum uncompressed size of a batch, in bytes (default: 5MB)
  MaxBatchByteSize int
  // optional: disable gzip compression of request bodies
  DisableCompression bool

  // optional: customize record builder
  Converter Converter
  // optional: custom marshaler, called once per batch with the full
  // []map[string]any payload; its output is sent as the request body
  Marshaler func(v any) ([]byte, error)
  // optional: fetch attributes from context
  AttrFromContext []func(ctx context.Context) []slog.Attr

  // optional: see slog.HandlerOptions
  AddSource   bool
  ReplaceAttr func(groups []string, a slog.Attr) slog.Attr
}

Other global parameters:

slogbetterstack.SourceKey = "runtime"
slogbetterstack.ContextKey = "context"
slogbetterstack.ErrorKeys = []string{"error", "err"}

Batching

Records are buffered and sent to Betterstack in gzip-compressed batches (unless DisableCompression is set), by a background goroutine. A batch is sent when:

• it holds MaxBatchSize records ;
• or it reaches MaxBatchByteSize bytes (uncompressed) ;
• or no record has been logged for MinBatchWait ;
• or the oldest buffered record has been waiting for MaxBatchWait.

The background goroutine is stopped automatically once the handler is garbage collected. Call Close() before exiting, to make sure the last buffered records are sent:

handler := slogbetterstack.Option{Token: "xxxxx"}.NewBetterstackHandler()
defer handler.(*slogbetterstack.BetterstackHandler).Close()

Example

import (
	"fmt"
	"net/http"
	"time"

	slogbetterstack "github.com/samber/slog-betterstack"

	"log/slog"
)

func main() {
	handler := slogbetterstack.Option{Level: slog.LevelDebug, Token: "xxxxx"}.NewBetterstackHandler()
	defer handler.(*slogbetterstack.BetterstackHandler).Close()

	logger := slog.New(handler)
	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", slog.Int("count", 1))
}

Tracing

Import the samber/slog-otel library.

import (
	slogbetterstack "github.com/samber/slog-betterstack"
	slogotel "github.com/samber/slog-otel"
	"go.opentelemetry.io/otel/sdk/trace"
)

func main() {
	tp := trace.NewTracerProvider(
		trace.WithSampler(trace.AlwaysSample()),
	)
	tracer := tp.Tracer("hello/world")

	ctx, span := tracer.Start(context.Background(), "foo")
	defer span.End()

	span.AddEvent("bar")

	logger := slog.New(
		slogbetterstack.Option{
			// ...
			AttrFromContext: []func(ctx context.Context) []slog.Attr{
				slogotel.ExtractOtelAttrFromContext([]string{"tracing"}, "trace_id", "span_id"),
			},
		}.NewBetterstackHandler(),
	)

	logger.ErrorContext(ctx, "a message")
}

🤝 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.