feature #492 Add support for configuring Gelf encoders in Monolog configuration (Tibor Rac, Tib-z, HypeMC)

This PR was merged into the 3.x branch.

Discussion
----------

Add support for configuring Gelf encoders in Monolog configuration

This commit introduces the ability to specify custom encoders (`json` and `compressed_json`) for Gelf publishers in Monolog's configuration.

Overview
This PR introduces an enhancement to the Symfony Monolog Bundle by adding a configuration option for setting the message encoder for the GELF handler's publisher. This change addresses a backward compatibility issue introduced in the 2.0 update of the graylog2/gelf-php package, which shifted the default message encoder from CompressedJsonEncoder to JsonEncoder. Thus an upgrade silently breakes the logging.

bzikarsky/gelf-php@f2625cf#diff-9520be6ea98f5ded11cbe62c500f1a8fef819810d8836d2b15189cdbc073900cR32
bzikarsky/gelf-php@f2625cf#diff-72a9d13c23b7d615833219f0dfc92be317d9a4981de7b4747e287db62aaa1079L69

In a Symfony project, to override this default behavior, users had to manually construct and define the transport, publisher, and encoder as a service and then use it in the Monolog configuration. This approach, while functional, is cumbersome. It would be more user-friendly to enable setting the encoder via a simple configuration option. The proposed change would be:

```
            gelf:
                type: gelf
                level: debug
                publisher:
                    hostname: '%env(resolve:LOGSTASH_HOSTNAME)%'
                    port: '%env(resolve:LOGSTASH_PORT)%'
                    encoder: compressed_json  # Optional: 'json' or 'compressed_json'
```
This new encoder configuration is optional and does not have an explicit default value, thereby preserving the existing behavior (albeit the recent default may not align with prior expectations).

While it might be tempting to expose more variability (like using class names or service IDs directly), overly customizable options may not add practical value and could complicate the configuration unnecessarily, 'coz YAGNI :)

Commits
-------

e208cca Fix CS
b2ee640 Use RuntimeException instead of InvalidConfigurationException in extension
1d2d39c Use RuntimeException instead of InvalidConfigurationException in extension
234ea20 Change encoder config node from scalar to enum
b9eedd6 Fix indentation
e86b0b4 Update GELF config documentation for clarity
b234af6 Remove tests that fake Gelf classes
7bf64b8 Fix typo in configuration comment
5cb4306 Fix compatibility issue, update class_alias to use DummyClassForClassExistsCheck
ec1de9e Add support for custom Gelf encoders in Monolog configuration

Author: GromNaN

CHANGELOG.md

@@ -12,6 +12,7 @@
 * Drop support for Symfony < 6.4
 * Add TelegramBotHandler `topic` support
 * Deprecate `sentry` and `raven` handler, use a `service` handler with [`sentry/sentry-symfony`](https://docs.sentry.io/platforms/php/guides/symfony/logs/) instead
+* Add configuration for Gelf encoders
 
 ## 3.10.0 (2023-11-06)
 

src/DependencyInjection/Configuration.php

@@ -52,7 +52,15 @@
  *   - [bubble]: bool, defaults to true
  *
  * - gelf:
- *   - publisher: {id: ...} or {hostname: ..., port: ..., chunk_size: ...}
+ *   - publisher: (one of the following configurations)
+ *     # Option 1: Service-based configuration
+ *     - id: string, service id of a publisher implementation
+ *
+ *     # Option 2: Direct connection configuration
+ *     - hostname: string, server hostname
+ *     - [port]: int, server port (default: 12201)
+ *     - [chunk_size]: int, UDP packet size (default: 1420)
+ *     - [encoder]: string, encoding format ('json' or 'compressed_json')
  *   - [level]: level name or int value, defaults to DEBUG
  *   - [bubble]: bool, defaults to true
  *
@@ -831,6 +839,7 @@ private function addGelfSection(ArrayNodeDefinition $handlerNode)
                         ->scalarNode('hostname')->end()
                         ->scalarNode('port')->defaultValue(12201)->end()
                         ->scalarNode('chunk_size')->defaultValue(1420)->end()
+                        ->enumNode('encoder')->values(['json', 'compressed_json'])->end()
                     ->end()
                     ->validate()
                         ->ifTrue(function ($v) {

src/DependencyInjection/MonologExtension.php

@@ -221,10 +221,28 @@ private function buildHandler(ContainerBuilder $container, $name, array $handler
                     ]);
                     $transport->setPublic(false);
 
+                    if (isset($handler['publisher']['encoder'])) {
+                        if ('compressed_json' === $handler['publisher']['encoder']) {
+                            $encoderClass = 'Gelf\Encoder\CompressedJsonEncoder';
+                        } elseif ('json' === $handler['publisher']['encoder']) {
+                            $encoderClass = 'Gelf\Encoder\JsonEncoder';
+                        } else {
+                            throw new \RuntimeException('The gelf message encoder must be either "compressed_json" or "json".');
+                        }
+
+                        $encoder = new Definition($encoderClass);
+                        $encoder->setPublic(false);
+
+                        $transport->addMethodCall('setMessageEncoder', [$encoder]);
+                    }
+
                     $publisher = new Definition('Gelf\Publisher', []);
                     $publisher->addMethodCall('addTransport', [$transport]);
                     $publisher->setPublic(false);
                 } elseif (class_exists('Gelf\MessagePublisher')) {
+                    if (isset($handler['publisher']['encoder']) && 'compressed_json' !== $handler['publisher']['encoder']) {
+                        throw new \RuntimeException('The Gelf\MessagePublisher publisher supports only the compressed json encoding. Omit the option to use the default encoding or use "compressed_json" as the encoder option.');
+                    }
                     $publisher = new Definition('Gelf\MessagePublisher', [
                         $handler['publisher']['hostname'],
                         $handler['publisher']['port'],

tests/DependencyInjection/ConfigurationTest.php

@@ -111,6 +111,28 @@ public function testGelfPublisherService($publisher)
         $this->assertEquals('gelf.publisher', $config['handlers']['gelf']['publisher']['id']);
     }
 
+    public function testGelfPublisherWithEncoder()
+    {
+        $configs = [
+            [
+                'handlers' => [
+                    'gelf' => [
+                        'type' => 'gelf',
+                        'publisher' => [
+                            'hostname' => 'localhost',
+                            'encoder' => 'compressed_json',
+                        ],
+                    ],
+                ],
+            ],
+        ];
+
+        $config = $this->process($configs);
+
+        $this->assertEquals('localhost', $config['handlers']['gelf']['publisher']['hostname']);
+        $this->assertEquals('compressed_json', $config['handlers']['gelf']['publisher']['encoder']);
+    }
+
     public function testArrays()
     {
         $configs = [