adding sdk console metrics exporter (#1055)

to make getting started easier (in opentelemetry.io docs), create an sdk-based metrics
exporter. this means we can export all signals without needing a protobuf implementation.
since console export is only useful for playing around, the change in format to a
simpler human-readable output seems reasonable.

examples/logs/getting_started.php

@@ -13,6 +13,13 @@ use OpenTelemetry\SDK\Trace\TracerProvider;
 
 require __DIR__ . '/../../vendor/autoload.php';
 
+/**
+ * Example of logging used in conjunction with tracing. The trace id and span id
+ * will be injected into the logged record.
+ * Note that logging output is human-readable JSON, and is not compatible with the
+ * OTEL format.
+ */
+
 $loggerProvider = new LoggerProvider(
     new SimpleLogsProcessor(
         (new ConsoleExporterFactory())->create()

examples/metrics/getting_started.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\API\Metrics\ObserverInterface;
+use OpenTelemetry\SDK\Metrics\Data\Temporality;
+use OpenTelemetry\SDK\Metrics\MeterProvider;
+use OpenTelemetry\SDK\Metrics\MetricExporter\ConsoleMetricsExporter;
+use OpenTelemetry\SDK\Metrics\MetricReader\ExportingReader;
+use OpenTelemetry\SDK\Resource\ResourceInfoFactory;
+
+require 'vendor/autoload.php';
+
+/**
+ * Basic async/observable metrics generation example. This uses the console
+ * metrics exporter to print metrics out in a human-readable format (but does
+ * not require protobuf or the OTLP exporter)
+ */
+
+$reader = new ExportingReader(
+    new ConsoleMetricsExporter(Temporality::DELTA)
+);
+
+$meterProvider = MeterProvider::builder()
+    ->setResource(ResourceInfoFactory::emptyResource())
+    ->addReader($reader)
+    ->build();
+
+$meterProvider
+    ->getMeter('demo_meter')
+    ->createObservableGauge('number', 'items', 'Random number')
+    ->observe(static function (ObserverInterface $observer): void {
+        $observer->observe(random_int(0, 256));
+    });
+
+//metrics are collected every time `collect()` is called
+$reader->collect();

examples/metrics/meter_provider_builder.php

@@ -5,8 +5,8 @@ declare(strict_types=1);
 namespace OpenTelemetry\Example;
 
 use OpenTelemetry\API\Metrics\ObserverInterface;
-use OpenTelemetry\Contrib\Otlp\ConsoleMetricExporterFactory;
 use OpenTelemetry\SDK\Metrics\MeterProvider;
+use OpenTelemetry\SDK\Metrics\MetricExporter\ConsoleMetricExporterFactory;
 use OpenTelemetry\SDK\Metrics\MetricReader\ExportingReader;
 
 require_once __DIR__ . '/../../vendor/autoload.php';

src/Contrib/Otlp/_register.php

@@ -3,7 +3,6 @@
 declare(strict_types=1);
 \OpenTelemetry\SDK\Registry::registerSpanExporterFactory('otlp', \OpenTelemetry\Contrib\Otlp\SpanExporterFactory::class);
 \OpenTelemetry\SDK\Registry::registerMetricExporterFactory('otlp', \OpenTelemetry\Contrib\Otlp\MetricExporterFactory::class);
-\OpenTelemetry\SDK\Registry::registerMetricExporterFactory('console', \OpenTelemetry\Contrib\Otlp\ConsoleMetricExporterFactory::class);
 
 \OpenTelemetry\SDK\Registry::registerTransportFactory('http', \OpenTelemetry\Contrib\Otlp\OtlpHttpTransportFactory::class);
 

src/SDK/Logs/Exporter/ConsoleExporter.php

@@ -13,6 +13,10 @@ use OpenTelemetry\SDK\Logs\LogRecordExporterInterface;
 use OpenTelemetry\SDK\Logs\ReadableLogRecord;
 use OpenTelemetry\SDK\Resource\ResourceInfo;
 
+/**
+ * A JSON console exporter for LogRecords. This is only useful for testing; the
+ * output is human-readable, and is not compatible with the OTLP format.
+ */
 class ConsoleExporter implements LogRecordExporterInterface
 {
     private TransportInterface $transport;

src/SDK/Metrics/MetricExporter/ConsoleMetricExporterFactory.php

@@ -2,18 +2,15 @@
 
 declare(strict_types=1);
 
-namespace OpenTelemetry\Contrib\Otlp;
+namespace OpenTelemetry\SDK\Metrics\MetricExporter;
 
 use OpenTelemetry\SDK\Metrics\MetricExporterFactoryInterface;
 use OpenTelemetry\SDK\Metrics\MetricExporterInterface;
-use OpenTelemetry\SDK\Registry;
 
 class ConsoleMetricExporterFactory implements MetricExporterFactoryInterface
 {
     public function create(): MetricExporterInterface
     {
-        $transport = Registry::transportFactory('stream')->create('php://stdout', 'application/x-ndjson');
-
-        return new MetricExporter($transport);
+        return new ConsoleMetricsExporter();
     }
 }

src/SDK/Metrics/MetricExporter/ConsoleMetricsExporter.php

@@ -0,0 +1,104 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Metrics\MetricExporter;
+
+use OpenTelemetry\SDK\Common\Instrumentation\InstrumentationScopeInterface;
+use OpenTelemetry\SDK\Metrics\Data\Metric;
+use OpenTelemetry\SDK\Metrics\Data\Temporality;
+use OpenTelemetry\SDK\Metrics\MetricExporterInterface;
+use OpenTelemetry\SDK\Metrics\MetricMetadataInterface;
+use OpenTelemetry\SDK\Resource\ResourceInfo;
+
+/**
+ * Console metrics exporter.
+ * Note that the output is human-readable JSON, not compatible with OTLP.
+ */
+class ConsoleMetricsExporter implements MetricExporterInterface
+{
+    /**
+     * @var string|Temporality|null
+     */
+    private $temporality;
+
+    /**
+     * @param string|Temporality|null $temporality
+     */
+    public function __construct($temporality = null)
+    {
+        $this->temporality = $temporality;
+    }
+    /**
+     * @inheritDoc
+     */
+    public function temporality(MetricMetadataInterface $metric)
+    {
+        return $this->temporality ?? $metric->temporality();
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function export(iterable $batch): bool
+    {
+        $resource = null;
+        $scope = null;
+        foreach ($batch as $metric) {
+            /** @var Metric $metric */
+            if (!$resource) {
+                $resource = $this->convertResource($metric->resource);
+            }
+            if (!$scope) {
+                $scope = $this->convertInstrumentationScope($metric->instrumentationScope);
+                $scope['metrics'] = [];
+            }
+            $scope['metrics'][] = $this->convertMetric($metric);
+        }
+        $output = [
+            'resource' => $resource,
+            'scope' => $scope,
+        ];
+        echo json_encode($output, JSON_PRETTY_PRINT) . PHP_EOL;
+
+        return true;
+    }
+
+    public function shutdown(): bool
+    {
+        return true;
+    }
+
+    public function forceFlush(): bool
+    {
+        return true;
+    }
+
+    private function convertMetric(Metric $metric): array
+    {
+        return [
+            'name' => $metric->name,
+            'description' => $metric->description,
+            'unit' => $metric->unit,
+            'data' => $metric->data,
+        ];
+    }
+
+    private function convertResource(ResourceInfo $resource): array
+    {
+        return [
+            'attributes' => $resource->getAttributes()->toArray(),
+            'dropped_attributes_count' => $resource->getAttributes()->getDroppedAttributesCount(),
+        ];
+    }
+    private function convertInstrumentationScope(InstrumentationScopeInterface $scope): array
+    {
+        return [
+            'name' => $scope->getName(),
+            'version' => $scope->getVersion(),
+            'attributes' => $scope->getAttributes()->toArray(),
+            'dropped_attributes_count' => $scope->getAttributes()->getDroppedAttributesCount(),
+            'schema_url' => $scope->getSchemaUrl(),
+        ];
+    }
+}

src/SDK/Metrics/MetricExporter/_register.php

@@ -3,4 +3,5 @@
 declare(strict_types=1);
 
 \OpenTelemetry\SDK\Registry::registerMetricExporterFactory('memory', \OpenTelemetry\SDK\Metrics\MetricExporter\InMemoryExporterFactory::class);
+\OpenTelemetry\SDK\Registry::registerMetricExporterFactory('console', \OpenTelemetry\SDK\Metrics\MetricExporter\ConsoleMetricExporterFactory::class);
 \OpenTelemetry\SDK\Registry::registerMetricExporterFactory('none', \OpenTelemetry\SDK\Metrics\MetricExporter\NoopMetricExporterFactory::class);

tests/Unit/Contrib/Otlp/ConsoleMetricExporterFactoryTest.php

@@ -1,21 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace OpenTelemetry\Tests\Unit\Contrib\Otlp;
-
-use OpenTelemetry\Contrib\Otlp\ConsoleMetricExporterFactory;
-use OpenTelemetry\Contrib\Otlp\MetricExporter;
-use PHPUnit\Framework\TestCase;
-
-/**
- * @covers \OpenTelemetry\Contrib\Otlp\ConsoleMetricExporterFactory
- */
-class ConsoleMetricExporterFactoryTest extends TestCase
-{
-    public function test_create(): void
-    {
-        $exporter = (new ConsoleMetricExporterFactory())->create();
-        $this->assertInstanceOf(MetricExporter::class, $exporter);
-    }
-}

tests/Unit/Contrib/Otlp/ProtobufSerializerTest.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Tests\Unit\Contrib\Otlp;
+
+use OpenTelemetry\Contrib\Otlp\ProtobufSerializer;
+use Opentelemetry\Proto\Collector\Trace\V1\ExportTraceServiceResponse;
+use OpenTelemetry\SDK\Common\Export\TransportInterface;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \OpenTelemetry\Contrib\Otlp\ProtobufSerializer
+ */
+class ProtobufSerializerTest extends TestCase
+{
+    public function test_empty_json_response(): void
+    {
+        $transport = $this->createMock(TransportInterface::class);
+        $transport->method('contentType')->willReturn('application/json');
+        $serializer = ProtobufSerializer::forTransport($transport);
+        $response = new ExportTraceServiceResponse();
+        $serializer->hydrate($response, '{}');
+
+        $this->assertNull($response->getPartialSuccess());
+    }
+}

tests/Unit/SDK/Metrics/MetricExporter/ConsoleMetricExporterFactoryTest.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Tests\Unit\SDK\Metrics\MetricExporter;
+
+use OpenTelemetry\SDK\Metrics\MetricExporter\ConsoleMetricExporterFactory;
+use OpenTelemetry\SDK\Metrics\MetricExporterInterface;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \OpenTelemetry\SDK\Metrics\MetricExporter\ConsoleMetricExporterFactory
+ */
+class ConsoleMetricExporterFactoryTest extends TestCase
+{
+    public function test_create(): void
+    {
+        $exporter = (new ConsoleMetricExporterFactory())->create();
+        $this->assertInstanceOf(MetricExporterInterface::class, $exporter);
+    }
+}