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README
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go.loglayer.dev/plugins/oteltrace
LogLayer plugin that injects the active OTel trace_id and span_id (plus optional trace flags, W3C trace state, and W3C baggage members) into every log entry that carries a context.Context. Use with non-OTel transports for log/trace correlation; transports/otellog does this automatically via the SDK.
Requires Go 1.25+ (driven by go.opentelemetry.io/otel). Ships as its own Go module so the OTel API's transitive deps don't bind users who don't import them.
Install
go get go.loglayer.dev/plugins/oteltrace
Documentation
Full reference and examples: https://go.loglayer.dev/plugins/oteltrace
Main library: https://go.loglayer.dev
Documentation
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Overview ¶
Package oteltrace provides a LogLayer plugin that injects OpenTelemetry trace and span IDs into log entries, enabling log/trace correlation for any transport (structured, HTTP, Datadog, etc.).
Use this plugin when your service runs OpenTelemetry tracing but you ship logs to a destination other than the OTel logs pipeline. The plugin reads the active span from each entry's per-call context (the one attached via WithContext) and emits trace_id and span_id, plus an optional trace_flags, as fields on the entry. Downstream UIs (Grafana, Tempo, Honeycomb, custom dashboards) can use these to link a log line back to its trace.
If you DO ship logs to the OTel pipeline via transports/otellog, you don't need this plugin — the OTel SDK reads the active span from the emission context and embeds the trace IDs on the exported log.Record automatically. Use this plugin when the destination doesn't speak OTel.
Usage:
import (
"go.loglayer.dev"
"go.loglayer.dev/plugins/oteltrace"
"go.loglayer.dev/transports/structured"
)
log := loglayer.New(loglayer.Config{
Transport: structured.New(structured.Config{}),
Plugins: []loglayer.Plugin{oteltrace.New(oteltrace.Config{})},
})
// Inside a handler whose context carries an OTel span:
handlerLog := log.WithContext(r.Context())
handlerLog.Info("served")
// {"level":"info","msg":"served","trace_id":"4bf...","span_id":"00f..."}
See https://go.loglayer.dev for usage guides and the full API reference.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func New ¶
func New(cfg Config) loglayer.Plugin
New constructs the plugin. The returned plugin implements [loglayer.DataHook]; when cfg.OnError is set it's wrapped via [loglayer.WithErrorReporter] so recovered hook panics reach the caller-supplied callback instead of the framework's stderr default.
Example ¶
New returns a plugin that injects the active OTel span's trace_id and span_id (read from the per-call context attached via WithContext) onto every entry. Use it when shipping logs to a non-OTel backend that still needs trace correlation.
t := lltesting.New(lltesting.Config{})
log := loglayer.New(loglayer.Config{
Transport: t,
DisableFatalExit: true,
Plugins: []loglayer.Plugin{oteltrace.New(oteltrace.Config{})},
})
log.Info("served")
Types ¶
type Config ¶
type Config struct {
// ID for the plugin. Defaults to "otel-trace-injector".
ID string
// TraceIDKey is the data key under which the trace ID is emitted.
// Defaults to "trace_id" (matching OTel JSON serialization). Common
// alternatives: "trace.id" (ECS), "traceId" (camelCase backends).
TraceIDKey string
// SpanIDKey is the data key under which the span ID is emitted.
// Defaults to "span_id".
SpanIDKey string
// TraceFlagsKey, when non-empty, also emits the trace flags byte
// (an int 0-255; bit 0 is the sampled flag) under that key. Empty
// means "don't emit" (the default).
TraceFlagsKey string
// TraceStateKey, when non-empty, emits the W3C trace state (vendor-
// specific routing/sampling information that rides with the trace
// context) as a single string under that key. Canonical form:
// "vendor1=val1,vendor2=val2". Empty means "don't emit" (the default).
// Skipped when the trace state is empty even if the key is set.
TraceStateKey string
// BaggageKeyPrefix, when non-empty, emits each W3C baggage member
// from p.Ctx as a separate attribute keyed "<prefix><member-key>".
// Common choice: "baggage." → baggage.user_id, baggage.tenant_id.
// Empty means "don't emit" (the default).
//
// Baggage is read independently of the trace span: a context can
// carry baggage with no active span, in which case those values are
// emitted on the entry without trace_id / span_id.
BaggageKeyPrefix string
// OnError is forwarded to the resulting Plugin's OnError. The
// LogLayer framework recovers extractor panics centrally; if you
// pass a non-nil OnError here, you'll see the recovered panic.
// Defaults to silent.
OnError func(err error)
}
Config holds plugin configuration.
Source Files