Configuration\CompositeResolver and SPI discovery (#1523)

* Configuration\CompositeResolver can discover additional configuration resolvers via SPI.

* Apply suggestions from code review

Co-authored-by: Tobias Bachert <[email protected]>

* Fix imports.

* Porting EnvSourceProvider changes from Nevay.

* Moved VlucasPhpdotenvProvider to sdk-configuration.

* Added SdkConfigurationResolver.

* Added SymfonyDotenvProvider.

* Removed vlucas/phpdotenv dev package.

* make style 😎

* Update deptrac for dotenv providers.

* Suppress Psalm errors for optional packages.

* Added phpstan ignoreErrors rules for optional dependency behavior.

* Added test for SPI-backed configuration loading via EnvSourceProvider

* Restructure SPI based test for EnvSourceProvider.

* Bumped SPI dependency.

* Added implied mixed return type to ResolverInterface::retrieveValue

---------

Co-authored-by: Tobias Bachert <[email protected]>

Author: ChrisLightfootWild

Common/Configuration/Resolver/CompositeResolver.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\SDK\Common\Configuration\Resolver;
 
+use Nevay\SPI\ServiceLoader;
 use OpenTelemetry\SDK\Common\Configuration\Configuration;
 
 /**
@@ -18,6 +19,7 @@ public static function instance(): self
     {
         static $instance;
         $instance ??= new self([
+            ...ServiceLoader::load(ResolverInterface::class),
             new EnvironmentResolver(),
             new PhpIniResolver(),
         ]);

Common/Configuration/Resolver/EnvironmentResolver.php

@@ -25,12 +25,7 @@ public function hasVariable(string $variableName): bool
         return !Configuration::isEmpty($env);
     }
 
-    /**
-     * @psalm-suppress InvalidReturnStatement
-     * @psalm-suppress InvalidReturnType
-     */
-    #[\Override]
-    public function retrieveValue(string $variableName)
+    public function retrieveValue(string $variableName): mixed
     {
         $value = getenv($variableName);
         if ($value === false) {

Common/Configuration/Resolver/PhpIniResolver.php

@@ -17,7 +17,7 @@ public function __construct(private readonly PhpIniAccessor $accessor = new PhpI
     }
 
     #[\Override]
-    public function retrieveValue(string $variableName)
+    public function retrieveValue(string $variableName): mixed
     {
         $value = $this->accessor->get($variableName) ?: '';
         if (is_array($value)) {
@@ -27,7 +27,6 @@ public function retrieveValue(string $variableName)
         return $value;
     }
 
-    #[\Override]
     public function hasVariable(string $variableName): bool
     {
         $value = $this->accessor->get($variableName);

Common/Configuration/Resolver/ResolverInterface.php

@@ -6,10 +6,7 @@
 
 interface ResolverInterface
 {
-    /**
-     * @return mixed
-     */
-    public function retrieveValue(string $variableName);
+    public function retrieveValue(string $variableName): mixed;
 
     public function hasVariable(string $variableName): bool;
 }

Common/Configuration/Resolver/SdkConfigurationResolver.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Configuration\Resolver;
+
+use Nevay\SPI\ServiceLoader;
+use Nevay\SPI\ServiceProviderDependency\PackageDependency;
+use OpenTelemetry\Config\SDK\Configuration\Environment\EnvSourceProvider;
+use OpenTelemetry\Config\SDK\Configuration\Environment\EnvSourceReader;
+use OpenTelemetry\Config\SDK\Configuration\Environment\LazyEnvSource;
+use OpenTelemetry\Config\SDK\Configuration\Environment\PhpIniEnvSource;
+use OpenTelemetry\Config\SDK\Configuration\Environment\ServerEnvSource;
+use OpenTelemetry\SDK\Common\Configuration\Configuration;
+
+/**
+ * @internal
+ */
+#[PackageDependency('open-telemetry/sdk-configuration', '*')]
+class SdkConfigurationResolver implements ResolverInterface
+{
+    private readonly EnvSourceReader $reader;
+
+    public function __construct()
+    {
+        $envSources = [];
+
+        /** @var EnvSourceProvider $envSourceProvider */
+        foreach (ServiceLoader::load(EnvSourceProvider::class) as $envSourceProvider) {
+            $envSources[] = new LazyEnvSource($envSourceProvider->getEnvSource(...));
+        }
+
+        $envSources[] = new ServerEnvSource();
+        $envSources[] = new PhpIniEnvSource();
+
+        $this->reader = new EnvSourceReader($envSources);
+    }
+
+    public function retrieveValue(string $variableName): mixed
+    {
+        return $this->reader->read($variableName);
+    }
+
+    public function hasVariable(string $variableName): bool
+    {
+        return !Configuration::isEmpty($this->reader->read($variableName));
+    }
+}

composer.json

@@ -32,7 +32,7 @@
         "ramsey/uuid": "^3.0 || ^4.0",
         "symfony/polyfill-mbstring": "^1.23",
         "symfony/polyfill-php82": "^1.26",
-        "tbachert/spi": "^1.0.1"
+        "tbachert/spi": "^1.0.5"
     },
     "autoload": {
         "psr-4": {
@@ -64,6 +64,9 @@
             "OpenTelemetry\\API\\Configuration\\ConfigEnv\\EnvComponentLoader": [
                 "OpenTelemetry\\API\\Instrumentation\\Configuration\\General\\ConfigEnv\\EnvComponentLoaderHttpConfig",
                 "OpenTelemetry\\API\\Instrumentation\\Configuration\\General\\ConfigEnv\\EnvComponentLoaderPeerConfig"
+            ],
+            "OpenTelemetry\\SDK\\Common\\Configuration\\Resolver\\ResolverInterface": [
+                "OpenTelemetry\\SDK\\Common\\Configuration\\Resolver\\SdkConfigurationResolver"
             ]
         }
     }