Using Redis with Drupal

Redis is a fast open-source in-memory database and cache, useful for application-level caching. For more information on this service, see the dedicated Redis page or the official Redis documentation.

Follow the instructions on this page to do one of the following:

• Add and configure Redis for Drupal if you have deployed Drupal manually.
• Fine-tune your existing configuration if you have deployed Drupal using a Platform.sh template.

Before you begin

You need:

• A Drupal version deployed on Platform.sh
• The Platform.sh CLI
• Composer
• The Config Reader library

You also need a settings.platformsh.php file from which you can manage the configuration of the Redis service. If you installed Drupal with a template, this file is already present in your project.

Add a Redis service

1. Configure the service

To define the service, use the redis-persistent endpoint:

# The name of the service container. Must be unique within a project.
<SERVICE_NAME>:
    type: redis-persistent:<VERSION>

Note that changing the name of the service replaces it with a brand new service and all existing data is lost. Back up your data before changing the service.

2. Add the relationship

To define the relationship, use the redis endpoint :

# Relationships enable access from this app to a given service.
# The example below shows simplified configuration leveraging a default service
# (identified from the relationship name) and a default endpoint.
# See the Application reference for all options for defining relationships and endpoints.
relationships:
    <SERVICE_NAME>: 

You can define <SERVICE_NAME> as you like, so long as it’s unique between all defined services and matches in both the application and services configuration.

The example above leverages default endpoint configuration for relationships. That is, it uses default endpoints behind-the-scenes, providing a relationship (the network address a service is accessible from) that is identical to the name of that service.

Depending on your needs, instead of default endpoint configuration, you can use explicit endpoint configuration.

With the above definition, the application container now has access to the service via the relationship <RELATIONSHIP_NAME> and its corresponding PLATFORM_RELATIONSHIPS environment variable.

For PHP, enable the extension for the service:

# PHP extensions.
runtime:
    extensions:
        - redis

3. Add the Drupal module

To add the Redis module to your project, run the following command:

composer require drupal/redis

Then commit the resulting changes to your composer.json and composer.lock files. Afterwards, you can enable the module with:

platform drush enable redis

Configure your Redis service

To configure your Redis service, follow these steps:

1. Add the following code at the top of your settings.platformsh.php file:

   settings.platformsh.php

    <?php
   
    $platformsh = new \Platformsh\ConfigReader\Config();
    if (!$platformsh->inRuntime()) {
       return;
    }

2. Add the following code at the end of the file:

   settings.platformsh.php

   <?php
   
   // Enable Redis caching.
    if ($platformsh->hasRelationship('rediscache') && !InstallerKernel::installationAttempted() && extension_loaded('redis')) {
      $redis = $platformsh->credentials('rediscache');
   
      // Set Redis as the default backend for any cache bin not otherwise specified.
      $settings['cache']['default'] = 'cache.backend.redis';
      $settings['redis.connection']['host'] = $redis['host'];
      $settings['redis.connection']['port'] = $redis['port'];
   
      // You can leverage Redis by using it for the lock and flood control systems
      // and the cache tag checksum.
      // To do so, apply the following changes to the container configuration.
      // Alternatively, copy the contents of the modules/contrib/redis/example.services.yml file
      // to your project-specific services.yml file.
      // Modify the contents to fit your needs and remove the following line.
      $settings['container_yamls'][] = 'modules/contrib/redis/example.services.yml';
   
      // Allow the services to work before the Redis module itself is enabled.
      $settings['container_yamls'][] = 'modules/contrib/redis/redis.services.yml';
   
      // To use Redis for container cache, add the classloader path manually.
      $class_loader->addPsr4('Drupal\\redis\\', 'modules/contrib/redis/src');
   
      // Use Redis for container cache.
      // The container cache is used to load the container definition itself.
      // This means that any configuration stored in the container isn't available
      // until the container definition is fully loaded.
      // To ensure that the container cache uses Redis rather than the
      // default SQL cache, add the following lines.
      $settings['bootstrap_container_definition'] = [
        'parameters' => [],
        'services' => [
          'redis.factory' => [
            'class' => 'Drupal\redis\ClientFactory',
          ],
          'cache.backend.redis' => [
            'class' => 'Drupal\redis\Cache\CacheBackendFactory',
            'arguments' => ['@redis.factory', '@cache_tags_provider.container', '@serialization.phpserialize'],
          ],
          'cache.container' => [
            'class' => '\Drupal\redis\Cache\PhpRedis',
            'factory' => ['@cache.backend.redis', 'get'],
            'arguments' => ['container'],
          ],
          'cache_tags_provider.container' => [
            'class' => 'Drupal\redis\Cache\RedisCacheTagsChecksum',
            'arguments' => ['@redis.factory'],
          ],
          'serialization.phpserialize' => [
            'class' => 'Drupal\Component\Serialization\PhpSerialize',
          ],
        ],
      ];
    }

   You can customize your configuration further using the inline comments from this example configuration. For more information on possible configuration options, see the README.txt file delivered with the Redis module or the official Redis documentation.

Verify Redis is running

To verify that Redis is running, run the following command:

platform redis info

The output produces information and statistics about Redis, showing that the service is up and running.