README

This is a read-only subtree split of https://github.com/open-telemetry/opentelemetry-php-contrib.

OpenTelemetry ServerTiming Propagator

This package provides a Server-Timing propagator to inject the current span context into Response datastructures.

The main goal is to allow client-side technology (Real User Monitoring, HTTP Clients) to record the server side context in order to allow referencing it.

Server-Timing response headers are especially useful for this approach, as they are accessible on the client side, even for the initial page load.

Requirements

• OpenTelemetry SDK and exporters (required to actually export traces)

Optional:

• OpenTelemetry extension (Some instrumentations can automatically use the TraceResponsePropagator)

Usage

Assuming there is an active SpanContext, you can inject it into your response as follows:

// your framework probably provides a datastructure to model HTTP responses
// and allows you to hook into the end of a request / listen to a matching event.
$response = new Response();

// get the current scope, bail out if none
$scope = Context::storage()->scope();
if (null === $scope) {
    return;
}

// create a PropagationSetterInterface that knows how to inject response headers
$propagationSetter = new class implements OpenTelemetry\Context\Propagation\PropagationSetterInterface {
    public function set(&$carrier, string $key, string $value) : void {
        $carrier->headers->set($key, $value);
    }
};
$propagator = new ServerTimingPropagator();
$propagator->inject($response, $propagationSetter, $scope->context());

Installation via composer

$ composer require open-telemetry/opentelemetry-propagation-server-timing

Installing dependencies and executing tests

From TraceResponse subdirectory:

$ composer install
$ ./vendor/bin/phpunit tests