Added Sdk::isDeveloperModeEnabled() helper.

src/SDK/Common/Configuration/Variables.php

@@ -139,4 +139,5 @@ interface Variables
     public const OTEL_PHP_AUTOLOAD_ENABLED = 'OTEL_PHP_AUTOLOAD_ENABLED';
     public const OTEL_PHP_INTERNAL_METRICS_ENABLED = 'OTEL_PHP_INTERNAL_METRICS_ENABLED'; //whether the SDK should emit its own metrics
     public const OTEL_PHP_DISABLED_INSTRUMENTATIONS = 'OTEL_PHP_DISABLED_INSTRUMENTATIONS';
+    public const OTEL_PHP_DEVELOPER_MODE_ENABLED = 'OTEL_PHP_DEVELOPER_MODE_ENABLED';
 }

src/SDK/Sdk.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\SDK;
 
+use Composer\InstalledVersions;
 use OpenTelemetry\API\Metrics\MeterProviderInterface;
 use OpenTelemetry\API\Trace\TracerProviderInterface;
 use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
@@ -43,6 +44,23 @@ public static function isInstrumentationDisabled(string $name): bool
         return in_array($name, Configuration::getList(Variables::OTEL_PHP_DISABLED_INSTRUMENTATIONS));
     }
 
+    /**
+     * Tests whether developer mode has been enabled by config.
+     */
+    public static function isDeveloperModeEnabled(): bool
+    {
+        if (Configuration::has(Variables::OTEL_PHP_DEVELOPER_MODE_ENABLED)) {
+            return Configuration::getBoolean(Variables::OTEL_PHP_DEVELOPER_MODE_ENABLED);
+        }
+
+        try {
+            return class_exists(InstalledVersions::class)
+                && InstalledVersions::getRootPackage()['dev'];
+        } catch (\Exception $exception) {
+            return false;
+        }
+    }
+
     public static function builder(): SdkBuilder
     {
         return new SdkBuilder();

tests/Unit/SDK/SdkTest.php

@@ -68,6 +68,21 @@ public static function instrumentationDisabledProvider(): array
         ];
     }
 
+    /**
+     * @dataProvider disabledProvider
+     */
+    public function test_developer_mode_can_be_enabled(string $value, bool $expected): void
+    {
+        $this->setEnvironmentVariable(Variables::OTEL_PHP_DEVELOPER_MODE_ENABLED, $value);
+
+        $this->assertEquals($expected, Sdk::isDeveloperModeEnabled());
+    }
+
+    public function test_developer_mode_auto_detected(): void
+    {
+        $this->assertTrue(Sdk::isDeveloperModeEnabled());
+    }
+
     public function test_builder(): void
     {
         $this->assertInstanceOf(SdkBuilder::class, Sdk::builder());