dartastic_opentelemetry_logging

Bridges package:logging records into the Dartastic OpenTelemetry SDK so any Dart application using the de-facto-standard Dart logging package gets trace/span correlation in its log records automatically.

Why

package:logging is what every Dart server framework and most Flutter apps use for structured application logs. Without a bridge, every consumer who wants trace-id correlation in their backend has to write the same ~15 lines of Logger.root.onRecord.listen(...) plumbing — easy to get the level mapping subtly wrong. This package is that plumbing, written once.

The bridge is opt-in: the OTel SDK does not depend on package:logging. Add this package only when you want the integration.

Usage

import 'package:dartastic_opentelemetry/dartastic_opentelemetry.dart';
import 'package:dartastic_opentelemetry_logging/dartastic_opentelemetry_logging.dart';
import 'package:logging/logging.dart';

Future<void> main() async {
  await OTel.initialize(serviceName: 'my-app');

  // After OTel.initialize so the default LoggerProvider exists.
  PackageLoggingBridge.install();

  Logger.root.level = Level.ALL;

  Logger('weather.api').info('serving forecast');

  // Records emitted from inside an active span are auto-correlated.
  await OTel.tracer().startActiveSpan('serve', (_) async {
    Logger('handler').warning('upstream slow');
  });

  // Cancel the StreamSubscription before the program exits, otherwise
  // the open subscription keeps the Dart isolate alive after main returns.
  await PackageLoggingBridge.uninstall();
  await OTel.shutdown();
}

Severity mapping

package:logging Level.value is mapped to OTel Severity using the same boundaries as the SDK's existing dart:developer bridge:

Attributes

• exception.type — set when the record has an error (uses runtimeType.toString()).
• exception.message — set when the record has an error (uses error.toString()).
• exception.stacktrace — set when the record has a stackTrace.
• logging.zone — hashCode of the originating Zone. Useful when correlating logs across isolates/zones; ignore otherwise.

The OTel logger name (instrumentation scope) defaults to the Logger's name, falling back to package.logging for Logger.root records.

Existing Logger.root.onRecord subscribers keep firing

Installing the bridge is additive. If your app already prints log records to stdout via a Logger.root.onRecord.listen(...) subscriber, those continue to fire. That matters for Cloud Run / Cloud Functions where the platform also collects stdout.

Lifecycle

The bridge holds a StreamSubscription on Logger.root.onRecord. Like any open subscription, an open subscription keeps the Dart isolate alive past main(). Always:

await PackageLoggingBridge.uninstall();
await OTel.shutdown();

before letting main() return. Forgetting to uninstall is the same class of bug as issue #33 in the SDK (short-lived CLIs hanging because a Timer/subscription was never cancelled).

License

Apache 2.0 — see LICENSE.