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SinkSeq — Flutter logs straight to Seq

· One min read
Altamir
Altamir
Maintainer

Version 0.1.0 introduced SinkSeq, allowing Flutter apps to send structured events in CLEF format to Seq servers — the same ecosystem many .NET teams already use.

Why Seq?​

Seq offers powerful search over structured properties, dashboards, and alerts. With CLEF, each log is a JSON document with @t, @mt, @l, and arbitrary properties — exactly what LogModel already produces.

Basic usage​

final seqSink = SinkSeq(
  'https://seq.example.com',
  apiKey: 'your-api-key',
  deviceIdentifier: 'checkout-app',
);

logger.addSink(seqSink);

await logger.log(
  'Order {orderId} placed',
  level: LogLevel.info,
  data: {'orderId': 'ORD-991'},
);

Improvements in 0.1.1 and 0.1.2​

Later releases fixed important production details:

  • Content-Type: application/vnd.serilog.clef header on POST
  • CLEF reserved fields (@t, @mt, @l, DeviceIdentifier) protected from data overwrites
  • SinkSeq.close() to release the internal HTTP pool
  • URL validation in release builds
  • Trailing slash URL normalization

Testability​

The constructor accepts an injected http.Client — essential for unit tests without network:

SinkSeq(
  'https://seq.test',
  client: mockClient,
);

Learn more​

See the full Seq integration guide in the documentation.