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Basic Setup

The smallest useful setup is:
  1. create a TraceRegistry
  2. create an exporter
  3. create Telemetry
  4. open a root span
  5. add logs or child spans
  6. complete the span
  7. call flush()

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Minimal Example

use Cognesy\Telemetry\Adapters\OTel\OtelExporter;
use Cognesy\Telemetry\Application\Registry\TraceRegistry;
use Cognesy\Telemetry\Application\Telemetry;
use Cognesy\Telemetry\Domain\Value\AttributeBag;

$telemetry = new Telemetry(
    registry: new TraceRegistry(),
    exporter: new OtelExporter(),
);

$telemetry->openRoot(
    key: 'run',
    name: 'demo.run',
    attributes: AttributeBag::fromArray([
        'component' => 'demo',
    ]),
);

$telemetry->log(
    key: 'run',
    name: 'demo.step',
    attributes: AttributeBag::fromArray([
        'status' => 'ok',
    ]),
);

$telemetry->complete('run');
$telemetry->flush();
// @doctest id="8cf7"

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Adding Child Spans

Use openChild() when a unit of work should sit under another span: 
$telemetry->openRoot('request', 'http.request');
$telemetry->openChild('llm', 'request', 'llm.inference');

$telemetry->complete('llm');
$telemetry->complete('request');
$telemetry->flush();
// @doctest id="035e"
The keys request and llm are local registry keys. They do not have to match the span name.

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Exporting To More Than One Backend

Use CompositeTelemetryExporter when you want more than one output: 
use Cognesy\Telemetry\Adapters\OTel\OtelExporter;
use Cognesy\Telemetry\Application\Exporter\CompositeTelemetryExporter;
use Cognesy\Telemetry\Application\Registry\TraceRegistry;
use Cognesy\Telemetry\Application\Telemetry;

$telemetry = new Telemetry(
    registry: new TraceRegistry(),
    exporter: new CompositeTelemetryExporter([
        new OtelExporter(),
        $logfireExporter,
        $langfuseExporter,
    ]),
);
// @doctest id="a92d"

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Notes

  • flush() matters. Exporters buffer observations until you call it.
  • TelemetryHub still exists, but Telemetry is the current class to use.
  • OtelExporter() without a transport is useful for local debugging and tests.