exampler filter from config

src/Contrib/Otlp/MetricExporterFactory.php

@@ -30,6 +30,11 @@ public function create(): MetricExporterInterface
 
     private function buildTransport(string $protocol): TransportInterface
     {
+        /**
+         * @todo (https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#periodic-exporting-metricreader)
+         * - OTEL_METRIC_EXPORT_INTERVAL
+         * - OTEL_METRIC_EXPORT_TIMEOUT
+         */
         $endpoint = Configuration::has(Variables::OTEL_EXPORTER_OTLP_METRICS_ENDPOINT)
             ? Configuration::getString(Variables::OTEL_EXPORTER_OTLP_METRICS_ENDPOINT)
             : Configuration::getString(Variables::OTEL_EXPORTER_OTLP_ENDPOINT);

src/SDK/Metrics/MeterProviderBuilder.php

@@ -8,6 +8,7 @@
 use OpenTelemetry\SDK\Common\Instrumentation\InstrumentationScopeFactory;
 use OpenTelemetry\SDK\Common\Time\ClockFactory;
 use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilter\WithSampledTraceExemplarFilter;
+use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilterInterface;
 use OpenTelemetry\SDK\Metrics\StalenessHandler\ImmediateStalenessHandlerFactory;
 use OpenTelemetry\SDK\Metrics\View\CriteriaViewRegistry;
 use OpenTelemetry\SDK\Resource\ResourceInfo;
@@ -18,6 +19,7 @@ class MeterProviderBuilder
     // @var array<MetricReaderInterface>
     private array $metricReaders = [];
     private ?ResourceInfo $resource = null;
+    private ?ExemplarFilterInterface $exemplarFilter = null;
 
     public function registerMetricReader(MetricReaderInterface $reader): self
     {
@@ -33,6 +35,13 @@ public function setResource(ResourceInfo $resource): self
         return $this;
     }
 
+    public function setExemplarFilter(ExemplarFilterInterface $exemplarFilter): self
+    {
+        $this->exemplarFilter = $exemplarFilter;
+
+        return $this;
+    }
+
     public function addReader(MetricReaderInterface $reader): self
     {
         $this->metricReaders[] = $reader;
@@ -53,7 +62,7 @@ public function build(): MeterProviderInterface
             new InstrumentationScopeFactory(Attributes::factory()),
             $this->metricReaders,
             new CriteriaViewRegistry(),
-            new WithSampledTraceExemplarFilter(),
+            $this->exemplarFilter ?? new WithSampledTraceExemplarFilter(),
             new ImmediateStalenessHandlerFactory(),
         );
     }

src/SDK/Metrics/MeterProviderFactory.php

@@ -9,6 +9,10 @@
 use OpenTelemetry\SDK\Common\Configuration\KnownValues;
 use OpenTelemetry\SDK\Common\Configuration\Variables;
 use OpenTelemetry\SDK\Common\Time\ClockFactory;
+use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilter\AllExemplarFilter;
+use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilter\NoneExemplarFilter;
+use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilter\WithSampledTraceExemplarFilter;
+use OpenTelemetry\SDK\Metrics\Exemplar\ExemplarFilterInterface;
 use OpenTelemetry\SDK\Metrics\MetricExporter\NoopMetricExporter;
 use OpenTelemetry\SDK\Metrics\MetricReader\ExportingReader;
 use OpenTelemetry\SDK\Resource\ResourceInfoFactory;
@@ -27,14 +31,6 @@ public function create(): MeterProviderInterface
         if (Sdk::isDisabled()) {
             return new NoopMeterProvider();
         }
-        /**
-         * @todo:
-         * - OTEL_METRICS_EXEMPLAR_FILTER
-         * - OTEL_METRIC_EXPORT_INTERVAL
-         * - OTEL_METRIC_EXPORT_TIMEOUT
-         * - OTEL_EXPORTER_OTLP_METRICS_HEADERS
-         */
-
         $exporterName = Configuration::getString(Variables::OTEL_METRICS_EXPORTER, KnownValues::VALUE_NONE);
         if ($exporterName === KnownValues::VALUE_NONE) {
             $exporter = new NoopMetricExporter();
@@ -48,10 +44,28 @@ public function create(): MeterProviderInterface
         }
         $reader = new ExportingReader($exporter, ClockFactory::getDefault());
         $resource = ResourceInfoFactory::defaultResource();
+        $exemplarFilter = $this->createExemplarFilter(Configuration::getEnum(Variables::OTEL_METRICS_EXEMPLAR_FILTER));
 
         return MeterProvider::builder()
             ->setResource($resource)
             ->addReader($reader)
+            ->setExemplarFilter($exemplarFilter)
             ->build();
     }
+
+    private function createExemplarFilter(string $name): ExemplarFilterInterface
+    {
+        switch ($name) {
+            case KnownValues::VALUE_WITH_SAMPLED_TRACE:
+                return new WithSampledTraceExemplarFilter();
+            case KnownValues::VALUE_ALL:
+                return new AllExemplarFilter();
+            case KnownValues::VALUE_NONE:
+                return new NoneExemplarFilter();
+            default:
+                self::logWarning('Unknown exemplar filter: ' . $name);
+
+                return new NoneExemplarFilter();
+        }
+    }
 }