slog: Channel handler

A Go channel Handler for slog Go library.

^{Sponsored by:}

Cloud-native search engine for observability - An OSS alternative to Splunk, Elasticsearch, Loki, and Tempo.

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-channel

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-channel

Handler options

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

  // Channel
  Channel chan *slog.Record
  Blocking bool // blocks on when channel is full

  // optional: customize record builder
  Converter Converter
  // 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:

slogchannel.SourceKey = "source"

Example

import (
	"fmt"
	"time"

	slogchannel "github.com/samber/slog-channel"

	"log/slog"
)

func main() {
	// warning: a too small buffer and too slow consumer might be blocking
	ch := make(chan *slog.Record, 100)
	defer close(ch)

	logger := slog.New(slogchannel.Option{Level: slog.LevelDebug, Channel: ch}.NewChannelHandler())
	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))

	record := <-ch
	fmt.Println(record)
}

Tracing

Import the samber/slog-otel library.

import (
	slogchannel "github.com/samber/slog-channel"
	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(
		slogchannel.Option{
			// ...
			AttrFromContext: []func(ctx context.Context) []slog.Attr{
				slogotel.ExtractOtelAttrFromContext([]string{"tracing"}, "trace_id", "span_id"),
			},
		}.NewChannelHandler(),
	)

	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

samber/slog-channel