reduce default set of resource detectors (#1471)

Limit the default detectors from everything to:
- sdk
- sdk_provided
- env

This is controlled by a new detector key, OTEL_PHP_DETECTORS=default (which is
the default if no value is provided). The previous behaviour can be restored
by explicitly setting OTEL_PHP_DETECTORS=all.

Author: brettmc

src/SDK/Common/Configuration/Defaults.php

@@ -113,7 +113,7 @@ interface Defaults
      * @see https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#language-specific-environment-variables
      */
     public const OTEL_PHP_TRACES_PROCESSOR = 'batch';
-    public const OTEL_PHP_DETECTORS = 'all';
+    public const OTEL_PHP_DETECTORS = 'default';
     public const OTEL_PHP_AUTOLOAD_ENABLED = 'false';
     public const OTEL_PHP_INTERNAL_METRICS_ENABLED = 'false';
     public const OTEL_PHP_DISABLED_INSTRUMENTATIONS = [];

src/SDK/Common/Configuration/KnownValues.php

@@ -189,6 +189,7 @@ interface KnownValues
     public const VALUE_STDOUT = 'stdout';
     public const VALUE_PSR3 = 'psr3';
     public const VALUE_EMPTY = '';
+    public const VALUE_DETECTORS_DEFAULT = 'default';
     public const VALUE_DETECTORS_ENVIRONMENT = 'env';
     public const VALUE_DETECTORS_HOST = 'host';
     public const VALUE_DETECTORS_OS = 'os';
@@ -199,6 +200,7 @@ interface KnownValues
     public const VALUE_DETECTORS_SERVICE = 'service';
     public const VALUE_DETECTORS_COMPOSER = 'composer';
     public const OTEL_PHP_DETECTORS = [
+        self::VALUE_DETECTORS_DEFAULT,
         self::VALUE_ALL,
         self::VALUE_DETECTORS_ENVIRONMENT,
         self::VALUE_DETECTORS_HOST,

src/SDK/Resource/ResourceInfoFactory.php

@@ -42,6 +42,12 @@ public static function defaultResource(): ResourceInfo
 
         foreach ($detectors as $detector) {
             switch ($detector) {
+                case Values::VALUE_DETECTORS_DEFAULT:
+                    $resourceDetectors[] = new Detectors\Sdk();
+                    $resourceDetectors[] = new Detectors\SdkProvided();
+                    $resourceDetectors[] = new Detectors\Environment();
+
+                    break;
                 case Values::VALUE_DETECTORS_SERVICE:
                     $resourceDetectors[] = new Detectors\Service();
 

tests/Integration/SDK/Resource/ResourceInfoFactoryTest.php

@@ -18,6 +18,7 @@ class ResourceInfoFactoryTest extends TestCase
 
     public function test_all_default_resources(): void
     {
+        $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', 'all');
         $resource = ResourceInfoFactory::defaultResource();
 
         $this->assertSame(ResourceAttributes::SCHEMA_URL, $resource->getSchemaUrl());

tests/Unit/SDK/Resource/ResourceInfoFactoryTest.php

@@ -84,6 +84,7 @@ public static function schemaUrlsToMergeProvider(): Generator
     #[Group('trace-compliance')]
     public function test_resource_service_name_default(): void
     {
+        $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', 'all');
         $resource = ResourceInfoFactory::defaultResource();
         $this->assertEquals('open-telemetry/opentelemetry', $resource->getAttributes()->get('service.name'));
     }
@@ -106,6 +107,7 @@ public function test_resource_with_invalid_environment_variable(): void
     #[Group('compliance')]
     public function test_resource_from_environment_service_name_takes_precedence_over_resource_attribute(): void
     {
+        $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', 'all');
         $this->setEnvironmentVariable('OTEL_RESOURCE_ATTRIBUTES', 'service.name=bar');
         $this->setEnvironmentVariable('OTEL_SERVICE_NAME', 'foo');
         $resource = ResourceInfoFactory::defaultResource();
@@ -115,6 +117,7 @@ public function test_resource_from_environment_service_name_takes_precedence_ove
     #[Group('compliance')]
     public function test_resource_from_environment_resource_attribute_takes_precedence_over_default(): void
     {
+        $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', 'all');
         $this->setEnvironmentVariable('OTEL_RESOURCE_ATTRIBUTES', 'service.name=foo');
         $resource = ResourceInfoFactory::defaultResource();
         $this->assertEquals('foo', $resource->getAttributes()->get('service.name'));
@@ -162,6 +165,35 @@ public function test_default_with_all_sdk_detectors(): void
         }
     }
 
+    /**
+     * From SDK 2.x, the default detectors are reduced to: sdk, sdk_provided, env
+     */
+    #[DataProvider('defaultProvider')]
+    public function test_default_detectors(?string $value): void
+    {
+        $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', $value);
+        $resource = ResourceInfoFactory::defaultResource();
+        $keys = array_keys($resource->getAttributes()->toArray());
+        $expected = [
+            'telemetry.sdk.name',
+            'telemetry.sdk.language',
+            'telemetry.sdk.version',
+            'telemetry.distro.name',
+            'telemetry.distro.version',
+            'service.name',
+        ];
+
+        $this->assertEquals($expected, $keys);
+    }
+
+    public static function defaultProvider(): array
+    {
+        return [
+            ['default'],
+            [null],
+        ];
+    }
+
     public function test_default_with_none_detectors(): void
     {
         $this->setEnvironmentVariable('OTEL_PHP_DETECTORS', 'none');