feature #30741 Add the Mailer component (fabpot)

This PR was merged into the 4.3-dev branch.

Discussion
----------

Add the Mailer component

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | upcoming

https://speakerdeck.com/fabpot/mailer

Commits
-------

69b9ee794c added the Mailer component

Author: fabpot

DependencyInjection/Configuration.php

@@ -26,6 +26,7 @@
 use Symfony\Component\HttpFoundation\Cookie;
 use Symfony\Component\Lock\Lock;
 use Symfony\Component\Lock\Store\SemaphoreStore;
+use Symfony\Component\Mailer\Mailer;
 use Symfony\Component\Messenger\MessageBusInterface;
 use Symfony\Component\PropertyInfo\PropertyInfoExtractorInterface;
 use Symfony\Component\Security\Csrf\CsrfTokenManagerInterface;
@@ -112,6 +113,7 @@ public function getConfigTreeBuilder()
         $this->addMessengerSection($rootNode);
         $this->addRobotsIndexSection($rootNode);
         $this->addHttpClientSection($rootNode);
+        $this->addMailerSection($rootNode);
 
         return $treeBuilder;
     }
@@ -1344,4 +1346,19 @@ private function addHttpClientOptionsSection(NodeBuilder $rootNode)
             ->end()
         ;
     }
+
+    private function addMailerSection(ArrayNodeDefinition $rootNode)
+    {
+        $rootNode
+            ->children()
+                ->arrayNode('mailer')
+                    ->info('Mailer configuration')
+                    ->{!class_exists(FullStack::class) && class_exists(Mailer::class) ? 'canBeDisabled' : 'canBeEnabled'}()
+                    ->children()
+                        ->scalarNode('dsn')->defaultValue('smtp://null')->end()
+                    ->end()
+                ->end()
+            ->end()
+        ;
+    }
 }

DependencyInjection/FrameworkExtension.php

@@ -74,6 +74,7 @@
 use Symfony\Component\Lock\Store\FlockStore;
 use Symfony\Component\Lock\Store\StoreFactory;
 use Symfony\Component\Lock\StoreInterface;
+use Symfony\Component\Mailer\Mailer;
 use Symfony\Component\Messenger\Handler\MessageHandlerInterface;
 use Symfony\Component\Messenger\MessageBus;
 use Symfony\Component\Messenger\MessageBusInterface;
@@ -316,6 +317,10 @@ public function load(array $configs, ContainerBuilder $container)
             $this->registerHttpClientConfiguration($config['http_client'], $container, $loader);
         }
 
+        if ($this->isConfigEnabled($container, $config['mailer'])) {
+            $this->registerMailerConfiguration($config['mailer'], $container, $loader);
+        }
+
         if ($this->isConfigEnabled($container, $config['web_link'])) {
             if (!class_exists(HttpHeaderSerializer::class)) {
                 throw new LogicException('WebLink support cannot be enabled as the WebLink component is not installed. Try running "composer require symfony/weblink".');
@@ -1854,6 +1859,16 @@ public function merge(array $options, array $defaultOptions)
         }
     }
 
+    private function registerMailerConfiguration(array $config, ContainerBuilder $container, XmlFileLoader $loader)
+    {
+        if (!class_exists(Mailer::class)) {
+            throw new LogicException('Mailer support cannot be enabled as the component is not installed. Try running "composer require symfony/mailer".');
+        }
+
+        $loader->load('mailer.xml');
+        $container->getDefinition('mailer.transport')->setArgument(0, $config['dsn']);
+    }
+
     /**
      * Returns the base path for the XSD files.
      *

Resources/config/mailer.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<container xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+
+    <services>
+        <service id="mailer" class="Symfony\Component\Mailer\Mailer">
+            <argument type="service" id="mailer.transport" />
+            <argument type="service" id="message_bus" on-invalid="ignore" />
+        </service>
+        <service id="Symfony\Component\Mailer\MailerInterface" alias="mailer" />
+
+        <service id="mailer.transport" class="Symfony\Component\Mailer\Transport\TransportInterface">
+            <factory class="Symfony\Component\Mailer\Transport" method="fromDsn" />
+            <argument /> <!-- env(MAILER_DSN) -->
+            <argument type="service" id="event_dispatcher" />
+            <argument type="service" id="http_client" on-invalid="ignore" />
+            <argument type="service" id="logger" on-invalid="ignore" />
+        </service>
+        <service id="Symfony\Component\Mailer\Transport\TransportInterface" alias="mailer.transport" />
+
+        <service id="mailer.messenger.message_handler" class="Symfony\Component\Mailer\Messenger\MessageHandler">
+            <argument type="service" id="mailer.transport" />
+            <tag name="messenger.message_handler" />
+        </service>
+    </services>
+</container>

Tests/DependencyInjection/ConfigurationTest.php

@@ -19,6 +19,7 @@
 use Symfony\Component\Config\Definition\Processor;
 use Symfony\Component\HttpClient\HttpClient;
 use Symfony\Component\Lock\Store\SemaphoreStore;
+use Symfony\Component\Mailer\Mailer;
 use Symfony\Component\Messenger\MessageBusInterface;
 
 class ConfigurationTest extends TestCase
@@ -336,6 +337,10 @@ class_exists(SemaphoreStore::class) && SemaphoreStore::isSupported() ? 'semaphor
                 'enabled' => !class_exists(FullStack::class) && class_exists(HttpClient::class),
                 'clients' => [],
             ],
+            'mailer' => [
+                'dsn' => 'smtp://null',
+                'enabled' => !class_exists(FullStack::class) && class_exists(Mailer::class),
+            ],
         ];
     }
 }

composer.json

@@ -42,6 +42,7 @@
         "symfony/form": "^4.3",
         "symfony/expression-language": "~3.4|~4.0",
         "symfony/http-client": "^4.3",
+        "symfony/mailer": "^4.3",
         "symfony/messenger": "^4.3",
         "symfony/mime": "^4.3",
         "symfony/process": "~3.4|~4.0",