refactor: drop guzzle dependency for PSR-18 alignment

.github/workflows/test.yml

@@ -41,6 +41,35 @@ jobs:
       - name: Run test suite
         run: composer run-script test
 
+  # Smoke-test the SDK against Symfony HttpClient as the discovered PSR-18
+  # implementation, ensuring the discovery + integration path doesn't
+  # regress on a non-Guzzle stack. Single PHP version is sufficient since
+  # the SDK doesn't reference symfony types directly.
+  tests-symfony:
+    runs-on: ubuntu-latest
+    name: Tests with Symfony HttpClient (PSR-18)
+    steps:
+      - name: Checkout
+        uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # v2
+        with:
+          php-version: '8.3'
+
+      - name: Swap PSR-18 implementation to Symfony HttpClient
+        run: |
+          composer remove --dev --no-update guzzlehttp/guzzle
+          composer require --dev --no-update \
+            "symfony/http-client:^6.0 || ^7.0" \
+            "nyholm/psr7:^1.0"
+
+      - name: Install dependencies
+        run: composer install --no-interaction --no-progress
+
+      - name: Run test suite
+        run: composer run-script test
+
   static-analysis:
     strategy:
       fail-fast: false

composer.json

@@ -18,19 +18,32 @@
   "license": "MIT",
   "minimum-stability": "dev",
   "prefer-stable": true,
+  "config": {
+    "allow-plugins": {
+      "php-http/discovery": false
+    }
+  },
   "require": {
     "php": "^7.4 || ^8",
     "ext-json": "*",
-    "guzzlehttp/guzzle": "^7",
+    "php-http/discovery": "^1.15",
     "psr/cache": "^1 || ^2 || ^3",
+    "psr/http-client": "^1.0",
+    "psr/http-client-implementation": "^1.0",
+    "psr/http-factory": "^1.0",
+    "psr/http-factory-implementation": "^1.0",
     "psr/log": "^1 || ^2 || ^3",
     "symfony/cache": "^5.1.0 || ^6 || ^7 || ^8"
   },
   "require-dev": {
-    "phpunit/phpunit": "=9.6.33",
-    "phpstan/phpstan": "=1.12.32"
+    "guzzlehttp/guzzle": "^7.4",
+    "guzzlehttp/psr7": "^2.0",
+    "phpstan/phpstan": "=1.12.32",
+    "phpunit/phpunit": "=9.6.33"
   },
   "suggest": {
+    "guzzlehttp/guzzle": "A widely-used PSR-18 HTTP client; auto-discovered when installed.",
+    "symfony/http-client": "Symfony's PSR-18 HTTP client; auto-discovered when installed.",
     "monolog/monolog": "A PSR-3 logger to receive SDK log output; pass it via the logger config option. The SDK defaults to Psr\\Log\\NullLogger."
   },
   "autoload": {
@@ -43,8 +56,7 @@
       "src/EvaluationCore/Util.php",
       "src/Flag/Util.php",
       "src/Assignment/AssignmentConstants.php",
-      "src/Exposure/ExposureConstants.php",
-      "src/Http/GuzzleConstants.php"
+      "src/Exposure/ExposureConstants.php"
     ]
   },
   "autoload-dev": {

src/Amplitude/Amplitude.php

@@ -2,9 +2,11 @@
 
 namespace AmplitudeExperiment\Amplitude;
 
-use AmplitudeExperiment\Http\HttpClientInterface;
-use AmplitudeExperiment\Http\GuzzleHttpClient;
+use AmplitudeExperiment\Http\HttpClientFactory;
 use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\StreamFactoryInterface;
 use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
 
@@ -21,7 +23,9 @@ class Amplitude
      * @var array<array<string,mixed>>
      */
     protected array $queue = [];
-    protected HttpClientInterface $httpClient;
+    protected ClientInterface $httpClient;
+    protected RequestFactoryInterface $requestFactory;
+    protected StreamFactoryInterface $streamFactory;
     private LoggerInterface $logger;
     private AmplitudeConfig $config;
 
@@ -30,7 +34,11 @@ public function __construct(string $apiKey, ?AmplitudeConfig $config = null)
         $this->apiKey = $apiKey;
         $this->config = $config ?? AmplitudeConfig::builder()->build();
         $this->logger = $this->config->logger ?? new NullLogger();
-        $this->httpClient = $this->config->httpClient ?? new GuzzleHttpClient($this->config->guzzleClientConfig);
+        [$this->httpClient, $this->requestFactory, $this->streamFactory] = HttpClientFactory::resolveAll(
+            $this->config->httpClient,
+            $this->config->requestFactory,
+            $this->config->retryConfig
+        );
     }
 
     public function flush(): void
@@ -67,7 +75,6 @@ public function __destruct()
      */
     private function post(string $url, array $payload): void
     {
-        $httpClient = $this->httpClient->getClient();
         $payloadJson = json_encode($payload);
 
         if ($payloadJson === false) {
@@ -77,12 +84,12 @@ private function post(string $url, array $payload): void
 
         $payloadString = $this->payloadToString($payload);
 
-        $request = $this->httpClient
-            ->createRequest('POST', $url, $payloadJson)
+        $request = $this->requestFactory->createRequest('POST', $url)
+            ->withBody($this->streamFactory->createStream($payloadJson))
             ->withHeader('Content-Type', 'application/json');
 
         try {
-            $response = $httpClient->sendRequest($request);
+            $response = $this->httpClient->sendRequest($request);
             if ($response->getStatusCode() != 200) {
                 $this->logger->error('[Amplitude] Failed to send event: ' . $payloadString . ', ' . $response->getStatusCode() . ' ' . $response->getReasonPhrase());
                 return;

src/Amplitude/AmplitudeConfig.php

@@ -4,7 +4,9 @@
 
 use AmplitudeExperiment\Assignment\AssignmentConfig;
 use AmplitudeExperiment\Assignment\AssignmentConfigBuilder;
-use AmplitudeExperiment\Http\HttpClientInterface;
+use AmplitudeExperiment\Http\RetryConfig;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
 use Psr\Log\LoggerInterface;
 
 /**
@@ -35,14 +37,23 @@ class AmplitudeConfig
      */
     public bool $useBatch;
     /**
-     * The underlying HTTP client to use for requests, if this is not set, the default {@link GuzzleHttpClient} will be used.
+     * The PSR-18 HTTP client to use for requests. If null, a PSR-18
+     * implementation is auto-discovered via php-http/discovery and wrapped
+     * in {@link \AmplitudeExperiment\Http\RetryingClient} using
+     * {@link $retryConfig}. A user-supplied client is used verbatim with
+     * no retry wrap.
      */
-    public ?HttpClientInterface $httpClient;
+    public ?ClientInterface $httpClient;
     /**
-     * @var array<string, mixed>
-     * The configuration for the underlying default {@link GuzzleHttpClient} client (if used). See {@link GUZZLE_DEFAULTS} for defaults.
+     * The PSR-17 request factory used to construct requests. If null, a
+     * PSR-17 factory is auto-discovered.
      */
-    public array $guzzleClientConfig;
+    public ?RequestFactoryInterface $requestFactory;
+    /**
+     * Retry configuration for the auto-wrapped client. Ignored when
+     * {@link $httpClient} is supplied — the user's client is used verbatim.
+     */
+    public ?RetryConfig $retryConfig;
     /**
      * Set to use a custom PSR-3 logger. If not set, a {@link \Psr\Log\NullLogger} is used
      * and SDK log messages are discarded. Pass any PSR-3 implementation (e.g. Monolog, or
@@ -66,30 +77,30 @@ class AmplitudeConfig
         'minIdLength' => 5,
         'flushQueueSize' => 200,
         'httpClient' => null,
-        'guzzleClientConfig' => [],
+        'requestFactory' => null,
+        'retryConfig' => null,
         'logger' => null,
     ];
 
-    /**
-     * @param array<string, mixed> $guzzleClientConfig
-     */
     public function __construct(
-        int                  $flushQueueSize,
-        int                  $minIdLength,
-        string               $serverZone,
-        string               $serverUrl,
-        bool                 $useBatch,
-        ?HttpClientInterface $httpClient,
-        array                $guzzleClientConfig,
-        ?LoggerInterface      $logger)
-    {
+        int $flushQueueSize,
+        int $minIdLength,
+        string $serverZone,
+        string $serverUrl,
+        bool $useBatch,
+        ?ClientInterface $httpClient,
+        ?RequestFactoryInterface $requestFactory,
+        ?RetryConfig $retryConfig,
+        ?LoggerInterface $logger
+    ) {
         $this->flushQueueSize = $flushQueueSize;
         $this->minIdLength = $minIdLength;
         $this->serverZone = $serverZone;
         $this->serverUrl = $serverUrl;
         $this->useBatch = $useBatch;
         $this->httpClient = $httpClient;
-        $this->guzzleClientConfig = $guzzleClientConfig;
+        $this->requestFactory = $requestFactory;
+        $this->retryConfig = $retryConfig;
         $this->logger = $logger;
     }
 

src/Amplitude/AmplitudeConfigBuilder.php

@@ -2,7 +2,9 @@
 
 namespace AmplitudeExperiment\Amplitude;
 
-use AmplitudeExperiment\Http\HttpClientInterface;
+use AmplitudeExperiment\Http\RetryConfig;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
 use Psr\Log\LoggerInterface;
 
 class AmplitudeConfigBuilder
@@ -12,11 +14,9 @@ class AmplitudeConfigBuilder
     protected string $serverZone = AmplitudeConfig::DEFAULTS['serverZone'];
     protected ?string $serverUrl = null;
     protected bool $useBatch = AmplitudeConfig::DEFAULTS['useBatch'];
-    protected ?HttpClientInterface $httpClient = AmplitudeConfig::DEFAULTS['httpClient'];
-    /**
-     * @var array<string, mixed>
-     */
-    protected array $guzzleClientConfig = AmplitudeConfig::DEFAULTS['guzzleClientConfig'];
+    protected ?ClientInterface $httpClient = AmplitudeConfig::DEFAULTS['httpClient'];
+    protected ?RequestFactoryInterface $requestFactory = AmplitudeConfig::DEFAULTS['requestFactory'];
+    protected ?RetryConfig $retryConfig = AmplitudeConfig::DEFAULTS['retryConfig'];
     protected ?LoggerInterface $logger = AmplitudeConfig::DEFAULTS['logger'];
 
     public function __construct()
@@ -53,18 +53,33 @@ public function useBatch(bool $useBatch): AmplitudeConfigBuilder
         return $this;
     }
 
-    public function httpClient(HttpClientInterface $httpClient): AmplitudeConfigBuilder
+    /**
+     * Supply a PSR-18 HTTP client. The SDK uses it verbatim — no retry wrap.
+     * If omitted, a client is auto-discovered and wrapped in
+     * {@link \AmplitudeExperiment\Http\RetryingClient} using {@link retryConfig}.
+     */
+    public function httpClient(ClientInterface $httpClient): AmplitudeConfigBuilder
     {
         $this->httpClient = $httpClient;
         return $this;
     }
 
     /**
-     * @param array<string, mixed> $guzzleClientConfig
+     * Supply a PSR-17 request factory. If omitted, a factory is auto-discovered.
+     */
+    public function requestFactory(RequestFactoryInterface $requestFactory): AmplitudeConfigBuilder
+    {
+        $this->requestFactory = $requestFactory;
+        return $this;
+    }
+
+    /**
+     * Configure retry behavior for the auto-discovered client. Ignored when
+     * a client is supplied via {@link httpClient()}.
      */
-    public function guzzleClientConfig(array $guzzleClientConfig): AmplitudeConfigBuilder
+    public function retryConfig(RetryConfig $retryConfig): AmplitudeConfigBuilder
     {
-        $this->guzzleClientConfig = $guzzleClientConfig;
+        $this->retryConfig = $retryConfig;
         return $this;
     }
 
@@ -90,7 +105,8 @@ public function build(): AmplitudeConfig
             $this->serverUrl,
             $this->useBatch,
             $this->httpClient,
-            $this->guzzleClientConfig,
+            $this->requestFactory,
+            $this->retryConfig,
             $this->logger
         );
     }

src/Exception/MissingHttpImplementationException.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace AmplitudeExperiment\Exception;
+
+use LogicException;
+
+/**
+ * Raised when the SDK cannot discover a PSR-18 client or PSR-17 factory and
+ * the consumer did not supply one via the config builder. Always indicates
+ * a configuration / installation gap, not a transient failure — extends
+ * {@link LogicException} so consumers can handle it distinctly from
+ * runtime transport faults.
+ */
+class MissingHttpImplementationException extends LogicException
+{
+}