OpenTelemetry¶

OpenTelemetry is a PECL extension that provides the low-level instrumentation hooks needed to generate distributed traces, metrics, and logs from PHP applications, following the vendor-neutral OpenTelemetry standard. It captures function entry and exit, timing, and exceptions at the engine level through observer hooks, which the pure-PHP open-telemetry/opentelemetry Composer package then turns into spans, exports, and context propagation.

Distributed tracing links related operations across process and service boundaries: a single incoming HTTP request might touch an application server, a database, a queue, and an external API, and OpenTelemetry ties every one of those operations into a single trace using a shared trace ID passed through headers.

The extension exists because auto-instrumentation, tracing library calls such as PDO or Guzzle without the developer manually wrapping every call, needs to hook into the Zend Engine at a level that pure PHP userland code cannot reach efficiently.

<?php

    // Requires composer require open-telemetry/sdk open-telemetry/exporter-otlp,
    // which depend on ext-opentelemetry for auto-instrumentation hooks.
    $tracer = (new \OpenTelemetry\SDK\Trace\TracerProviderFactory())
        ->create()
        ->getTracer('example-app');

    $span = $tracer->spanBuilder('handle-request')->startSpan();
    $scope = $span->activate();

    try {
        // ... application code ...
    } finally {
        $span->end();
        $scope->detach();
    }

?>

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OpenTelemetry¶

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