bug #20891 Add support for REDIS_URL environment variables. (robinvdv…

…leuten)

This PR was submitted for the master branch but it was merged into the 3.2 branch instead (closes #20891).

Discussion
----------

Add support for REDIS_URL environment variables.

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #20850
| License       | MIT
| Doc PR        | -

In most PAAS solutions - Heroku for example - the Redis connection string is exposed as an environment variable like `REDIS_URL`. This PR adds support for those by allowing the following config;

```yml
framework:
    cache:
        default_redis_provider: "%env(REDIS_URL)%"
```

In the referenced issue there was some discussion about maybe a new config options like `default_redis_url`, but this makes it hard to check in the extension for the case that an user configured a custom _default_redis_provider_ and also has configured the default url.

Commits
-------

4e6086f Add support for REDIS_URL environment variables.

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php

@@ -96,7 +96,9 @@ private function getNamespace($seed, $id)
      */
     public static function getServiceProvider(ContainerBuilder $container, $name)
     {
-        if (0 === strpos($name, 'redis://')) {
+        $container->resolveEnvPlaceholders($name, null, $usedEnvs);
+
+        if (0 === strpos($name, 'redis://') || $usedEnvs) {
             $dsn = $name;
 
             if (!$container->hasDefinition($name = md5($dsn))) {

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/cache_env_var.php

@@ -0,0 +1,9 @@
+<?php
+
+$container->setParameter('env(REDIS_URL)', 'redis://paas.com');
+
+$container->loadFromExtension('framework', array(
+    'cache' => array(
+        'default_redis_provider' => '%env(REDIS_URL)%',
+    ),
+));

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/cache_env_var.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" ?>
+<container xmlns="http://symfony.com/schema/dic/services"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xmlns:framework="http://symfony.com/schema/dic/symfony"
+           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd
+        http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
+
+    <parameters>
+        <parameter key="env(REDIS_URL)">redis://paas.com</parameter>
+    </parameters>
+
+    <framework:config>
+        <framework:cache>
+            <framework:default-redis-provider>%env(REDIS_URL)%</framework:default-redis-provider>
+        </framework:cache>
+    </framework:config>
+</container>

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/cache_env_var.yml

@@ -0,0 +1,6 @@
+parameters:
+    env(REDIS_URL): redis://paas.com
+
+framework:
+    cache:
+        default_redis_provider: "%env(REDIS_URL)%"

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php

@@ -697,6 +697,34 @@ public function testPropertyInfoEnabled()
         $this->assertTrue($container->has('property_info'));
     }
 
+    public function testCacheDefaultRedisProvider()
+    {
+        $container = $this->createContainerFromFile('cache');
+
+        $redisUrl = 'redis://localhost';
+        $providerId = md5($redisUrl);
+
+        $this->assertTrue($container->hasDefinition($providerId));
+
+        $url = $container->getDefinition($providerId)->getArgument(0);
+
+        $this->assertSame($redisUrl, $url);
+    }
+
+    public function testCacheDefaultRedisProviderWithEnvVar()
+    {
+        $container = $this->createContainerFromFile('cache_env_var');
+
+        $redisUrl = 'redis://paas.com';
+        $providerId = md5($redisUrl);
+
+        $this->assertTrue($container->hasDefinition($providerId));
+
+        $url = $container->getDefinition($providerId)->getArgument(0);
+
+        $this->assertSame($redisUrl, $url);
+    }
+
     public function testCachePoolServices()
     {
         $container = $this->createContainerFromFile('cache');