Add PSR3 support for logging, instead of syslog/error_log

README.md

@@ -44,6 +44,7 @@ $eppoClient = EppoClient::init(
    $cache // optional, must be an instance of PSR-16 SimpleCache\CacheInterface. If not passed, FileSystem cache will be used
    $httpClient // optional, must be an instance of PSR-18 ClientInterface. If not passed, Discovery will be used to find a suitable implementation
    $requestFactory // optional, must be an instance of PSR-17 Factory. If not passed, Discovery will be used to find a suitable implementation
+   $logger // optional, must be an instance of PSR-3 LoggerInterface for SDK logs
 );
 ```
 
@@ -131,6 +132,9 @@ The `init` function accepts the following optional configuration arguments.
 | **`assignmentLogger`** | AssignmentLogger/IBanditLogger     | Logs assignment events back to data warehoouse                                                      | `null`  |
 | **`httpClient`**       | ClientInterface                    | For making HTTP requests. If not passed, Discovery will attempt to autoload an applicable pacakge   | `null`  |
 | **`requestFactory`**   | RequestFactoryInterface            | Instance of PSR-17 Factory. If not passed, Discovery will be used to find a suitable implementation | null    |
+| **`logger`**           | PSR-3 LoggerInterface              | Logs SDK warnings/errors (replaces `syslog`/`error_log`)                                             | `null`  |
+
+To preserve the previous syslog behavior, pass a PSR-3 logger configured for syslog, such as Monolog with a SyslogHandler.
 
 ## Assignment logger
 
@@ -216,6 +220,7 @@ $eppoClient = EppoClient::init(
    $cache // optional, must be an instance of PSR-16 SimpleInterface. If not passed, FileSystem cache will be used
    $httpClient // optional, must be an instance of PSR-18 ClientInterface. If not passed, Discovery will be used to find a suitable implementation
    $requestFactory // optional, must be an instance of PSR-17 Factory. If not passed, Discovery will be used to find a suitable implementation
+   $logger // optional, must be an instance of PSR-3 LoggerInterface for SDK logs
 );
 
 $eppoClient->startPolling();

composer.json

@@ -25,6 +25,7 @@
     "php": "^8.1",
     "ext-json": "*",
     "psr/simple-cache": "3.*",
+    "psr/log": "^2.0|^3.0",
     "shrikeh/teapot": "^2.3",
     "composer/semver": "^3.4",
     "php-http/discovery": "^1.17",

src/Config/ConfigurationLoader.php

@@ -7,14 +7,20 @@
 use Eppo\DTO\FlagConfigResponse;
 use Eppo\Exception\HttpRequestException;
 use Eppo\Exception\InvalidApiKeyException;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerAwareTrait;
+use Psr\Log\NullLogger;
 
-class ConfigurationLoader
+class ConfigurationLoader implements LoggerAwareInterface
 {
+    use LoggerAwareTrait;
+
     public function __construct(
         private readonly APIRequestWrapper $apiRequestWrapper,
         public readonly ConfigurationStore $configurationStore,
         private readonly int $cacheAgeLimitMillis = 30 * 1000
     ) {
+        $this->setLogger(new NullLogger());
     }
 
     /**
@@ -46,7 +52,9 @@ public function fetchAndStoreConfiguration(?string $flagETag): void
             $responseData = json_decode($response->body, true);
 
             if ($responseData === null) {
-                syslog(LOG_WARNING, "[Eppo SDK] Empty or invalid response from the configuration server.");
+                $this->logger->warning(
+                    '[Eppo SDK] Empty or invalid response from the configuration server.'
+                );
                 return;
             }
             $fcr = FlagConfigResponse::fromArray($responseData);
@@ -79,7 +87,9 @@ public function fetchAndStoreConfiguration(?string $flagETag): void
                     // Configuration object.
                     $banditResource = $this->apiRequestWrapper->getBandits();
                     if (!$banditResource?->body) {
-                        syslog(E_ERROR, "[Eppo SDK] Empty or invalid bandit response from the configuration server.");
+                        $this->logger->error(
+                            '[Eppo SDK] Empty or invalid bandit response from the configuration server.'
+                        );
                     } else {
                         $banditResponse = new ConfigResponse($banditResource->body, date('c'), $banditResource->eTag);
                     }

src/Config/ConfigurationStore.php

@@ -3,16 +3,22 @@
 namespace Eppo\Config;
 
 use Eppo\DTO\ConfigurationWire\ConfigurationWire;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerAwareTrait;
+use Psr\Log\NullLogger;
 use Psr\SimpleCache\CacheInterface;
 use Throwable;
 
-class ConfigurationStore
+class ConfigurationStore implements LoggerAwareInterface
 {
+    use LoggerAwareTrait;
+
     private const CONFIG_KEY = "EPPO_configuration_v1";
     private ?Configuration $configuration = null;
 
     public function __construct(private readonly CacheInterface $cache)
     {
+        $this->setLogger(new NullLogger());
     }
 
     public function getConfiguration(): Configuration
@@ -37,7 +43,10 @@ public function getConfiguration(): Configuration
             return $this->configuration;
         } catch (Throwable $e) {
             // Safe to ignore as the const `CONFIG_KEY` contains no invalid characters
-            syslog(LOG_ERR, "[Eppo SDK] Error loading config from cache " . $e->getMessage());
+            $this->logger->error(
+                '[Eppo SDK] Error loading config from cache ' . $e->getMessage(),
+                ['exception' => $e]
+            );
             return Configuration::emptyConfig();
         }
     }
@@ -49,7 +58,10 @@ public function setConfiguration(Configuration $configuration): void
             $this->cache->set(self::CONFIG_KEY, json_encode($configuration->toConfigurationWire()->toArray()));
         } catch (Throwable $e) {
             // Safe to ignore as the const `CONFIG_KEY` contains no invalid characters
-            syslog(LOG_ERR, "[Eppo SDK] Error loading config from cache " . $e->getMessage());
+            $this->logger->error(
+                '[Eppo SDK] Error saving config to cache ' . $e->getMessage(),
+                ['exception' => $e]
+            );
         }
     }
 }

src/DTO/Bandit/AttributeSet.php

@@ -32,11 +32,6 @@ public function __construct(
         foreach ($numericAttributes as $key => $value) {
             if (self::isNumberType($value)) {
                 $numeric[$key] = $value;
-            } else {
-                syslog(
-                    LOG_WARNING,
-                    "[Eppo SDK] non-numeric attribute passed in `\$numericAttributes` for key $key"
-                );
             }
         }
         $this->numericAttributes = $numeric;
@@ -51,8 +46,6 @@ public static function fromArray(array $attributes): self
                 $numericAttributes[$key] = $value;
             } elseif (self::isCategoricalType($value)) {
                 $categoricalAttributes[$key] = $value;
-            } else {
-                syslog(LOG_WARNING, "[Eppo SDK] Unsupported attribute type: " . gettype($value));
             }
         }
         return new self($numericAttributes, $categoricalAttributes);

src/DTO/Bandit/Bandit.php

@@ -30,10 +30,6 @@ public static function fromArray(array $arr): Bandit
                 $updatedAt = new DateTime($arr['updatedAt']);
             }
         } catch (\Exception $e) {
-            syslog(
-                LOG_WARNING,
-                "[Eppo SDK] invalid timestamp for bandit model {$arr['updatedAt']}: " . $e->getMessage()
-            );
             $updatedAt = new DateTime();
         } finally {
             return new Bandit(