LogLayer for Go

LogLayerUnifies Go Logging

A consistent logging experience for Go, on top of any logging library.

Why Use LogLayer?
Quickstart
GitHub (MIT Licensed)
LogLayer logo by Akshaya Madhavan

Structured Logging

Write logs with a fluent API that makes adding fields, metadata, and errors simple.

Bring Your Own Logger

Start with the built-in pretty or structured transport, then switch to zerolog, zap, slog, or your own logger later without changing application code.

Extensible Plugin System

Transform, enrich, redact, and filter logs at six lifecycle points to customize the pipeline end to end.

Multi-Transport Fan-out

Send the same entry to several transports at once, and use named groups to route specific entries to specific transports.

HTTP and Cloud Shipping

Built-in batched HTTP transport plus a Datadog Logs intake transport. Drop-in support for any service with a JSON-over-HTTP intake.

First-class Testing

Capture entries with the testing transport for assertions, or use loglayer.NewMock() for a silent logger in code under test.

Quick Example ​

go
package main

import (
    "errors"

    "go.loglayer.dev"
    "go.loglayer.dev/transports/structured"
)

func main() {
    log := loglayer.New(loglayer.Config{
        Transport: structured.New(structured.Config{}),
    })

    // WithFields returns a NEW logger; assign it.
    log = log.WithFields(loglayer.Fields{"service": "api"})

    log.WithMetadata(loglayer.Metadata{"userId": "1234"}).
        WithError(errors.New("something went wrong")).
        Error("user action failed")
}
json
{
  "level": "error",
  "time": "2026-04-25T12:00:00Z",
  "msg": "user action failed",
  "service": "api",
  "userId": "1234",
  "err": { "message": "something went wrong" }
}

Transports ​

Renderers ​

Self-contained transports that format the entry and write it to an io.Writer. Pick one of these when you want LogLayer to do the rendering itself.

NameDescription
PrettyColorized, theme-aware terminal output. Recommended for local dev.
StructuredOne JSON object per log entry. Recommended for production.
ConsolePlain fmt.Println-style output to stdout/stderr; minimal formatting.
TestingCaptures entries in memory for tests.
BlankDelegates dispatch to a user-supplied function. For prototyping or one-off integrations.

Network ​

Transports that ship log entries to a remote endpoint over the network. Async + batched by default.

NameDescription
HTTPGeneric batched HTTP POST to any endpoint. Pluggable Encoder.
DatadogDatadog Logs HTTP intake. Site-aware URL, DD-API-KEY header, status mapping.

Supported Loggers ​

Transports that hand the entry off to an existing third-party logger you already configure. Pick one of these when you have an established logging stack and want LogLayer's API on top.

NameDescription
ZerologWraps a *zerolog.Logger
ZapWraps a *zap.Logger
log/slogWraps a stdlib *slog.Logger. Forwards WithContext to handlers.
phuslu/logHigh-performance zero-alloc JSON logger. Always exits on fatal.
logrusThe classic structured logger
charmbracelet/logPretty terminal-friendly logger from Charm
OpenTelemetry LogsEmits to an OTel log.Logger. Forwards WithContext so SDK processors can correlate with the active span.

Plugins ​

Hook into the LogLayer pipeline to transform metadata, fields, data, messages, log level, or per-transport dispatch.

NameDescription
RedactReplace values for a configured set of keys (and optional regex patterns) before metadata or fields reach a transport. Walks structs, maps, and slices via reflection; preserves the runtime type.
SamplingDrop a fraction of emissions to keep volume and cost under control. FixedRate (per-emission Bernoulli draw), FixedRatePerLevel (per-level rate), and Burst (rate cap per rolling window). Composes with itself for "1% kept, capped at 100/sec" patterns.
Format StringsOpt the logger into fmt.Sprintf-style format strings: log.Info("user %d", id) resolves to "user 1234" before downstream hooks see it.
Datadog APM Trace InjectorInject the active Datadog APM trace and span IDs (dd.trace_id, dd.span_id) into every log entry that carries a context, enabling Datadog's log/trace correlation. Tracer-agnostic; bring your own dd-trace-go (v1 or v2).
OpenTelemetry Trace InjectorInject the active OTel trace_id and span_id (and optional trace_flags) into every log entry that carries a context. Use with non-OTel transports for log/trace correlation; the OTel pipeline does this itself when shipping via transports/otellog.

LogLayer for Go is made with ❤️ by Theo Gravity / Disaresta. Logo by Akshaya Madhavan.