slog: Betterstack handler

🚀 Install

go get github.com/samber/slog-betterstack

💡 Usage

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: max records per HTTP request (default: 100)
  BatchSize int
  // optional: max delay before a partial batch is sent (default: 1s)
  FlushInterval time.Duration
  // optional: records buffered while a batch is in flight (default: 1000).
  // When the queue is full, records are dropped and reported through OnError.
  QueueSize int
  // optional: retries after a network error, 429 or 5xx (default: 3, -1 disables)
  MaxRetries int
  // optional: delay before the first retry, doubled on each following one, with random jitter (default: 500ms)
  RetryBackoff time.Duration
  // optional: called when a record cannot be delivered
  // (default: errors are ignored)
  OnError func(err error)

  // optional: customize record builder
  Converter Converter
  // optional: custom marshaler
  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
}

slogbetterstack.Option{
  Token:   "xxxxx",
  OnError: func(err error) { fmt.Fprintf(os.Stderr, "slog-betterstack: %v\n", err) },
}.NewBetterstackHandler()

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

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

logger := slog.New(handler)

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.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 (
	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

# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test

👤 Contributors

💫 Show your support

📝 License