OtlpHttpExporter.php

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<?php
namespace Wikimedia\Telemetry;
 
use GuzzleHttp\Psr7\Utils;
use Psr\Http\Client\ClientExceptionInterface;
use Psr\Http\Client\ClientInterface;
use Psr\Http\Message\RequestFactoryInterface;
use Psr\Log\LoggerInterface;
 
class OtlpHttpExporter implements ExporterInterface {
    private ClientInterface $client;
    private RequestFactoryInterface $requestFactory;
    private LoggerInterface $logger;
 
    private string $endpoint;
 
    private string $serviceName;
 
    private string $hostName;
 
    public function __construct(
        ClientInterface $client,
        RequestFactoryInterface $requestFactory,
        LoggerInterface $logger,
        string $uri,
        string $serviceName,
        string $hostName
    ) {
        $this->client = $client;
        $this->requestFactory = $requestFactory;
        $this->logger = $logger;
        $this->endpoint = $uri;
        $this->serviceName = $serviceName;
        $this->hostName = $hostName;
    }
 
    public function export( TracerState $tracerState ): void {
        $spanContexts = $tracerState->getSpanContexts();
        if ( count( $spanContexts ) === 0 ) {
            return;
        }
 
        $resourceInfo = array_filter( [
            'service.name' => $this->serviceName,
            'host.name' => $this->hostName,
            "server.socket.address" => $_SERVER['SERVER_ADDR'] ?? null,
        ] );
 
        $data = [
            'resourceSpans' => [
                [
                    'resource' => [
                        'attributes' => OtlpSerializer::serializeKeyValuePairs( $resourceInfo )
                    ],
                    'scopeSpans' => [
                        [
                            'scope' => [
                                'name' => 'org.wikimedia.telemetry',
                            ],
                            'spans' => $spanContexts
                        ]
                    ]
                ]
            ]
        ];
 
        $request = $this->requestFactory->createRequest( 'POST', $this->endpoint )
            ->withHeader( 'Content-Type', 'application/json' )
            ->withBody( Utils::streamFor( json_encode( $data ) ) );
 
        try {
            $response = $this->client->sendRequest( $request );
            if ( $response->getStatusCode() !== 200 ) {
                $this->logger->error( 'Failed to export trace data' );
            }
        } catch ( ClientExceptionInterface $e ) {
            $this->logger->error( 'Failed to connect to exporter', [ 'exception' => $e ] );
        }
 
        // Clear out finished spans after exporting them.
        $tracerState->clearSpanContexts();
    }
}