Using Memcached with Drupal 8.x
Platform.sh recommends using Redis for caching with Drupal 8 over Memcached, as Redis offers better performance when dealing with larger values as Drupal tends to produce. However, Memcached is also available if desired and is fully supported.
Requirements
Add a Memcached service
First you need to create a Memcached service. In your .platform/services.yaml
file, add or uncomment the following:
cacheservice:
type: memcached:1.4
That will create a service named cacheservice
, of type memcached
, specifically version 1.4
.
Expose the Memcached service to your application
In your .platform.app.yaml
file, we now need to open a connection to the new Memcached service. Under the relationships
section, add the following:
relationships:
cache: "cacheservice:memcached"
The key (left side) is the name that will be exposed to the application in the PLATFORM_RELATIONSHIPS
variable. The right hand side is the name of the service we specified above (cacheservice
) and the endpoint (memcached
). If you named the service something different above, change cacheservice
to that.
Add the Memcached PHP extension
You will need to enable the PHP Memcached extension. In your .platform.app.yaml
file, add the following right after the type
block:
# Additional extensions
runtime:
extensions:
- memcached
Add the Drupal module
You will need to add the Memcache module to your project. If you are using Composer to manage your Drupal 8 site (which we recommend), simply run:
composer require drupal/memcache
Then commit the resulting changes to your composer.json
and composer.lock
files.
note
You must commit and deploy your code before continuing, then enable the module. The memcache module must be enabled before it is configured in the
settings.platformsh.php
file.
Configuration
The Drupal Memcache module must be configured via settings.platformsh.php
.
Place the following at the end of settings.platformsh.php
. Note the inline comments, as you may wish to customize it further. Also review the README.txt
file that comes with the memcache module, as it has a more information on possible configuration options. For instance, you may want to consider using memcache for locking as well and configuring cache stampede protection.
The example below is intended as a "most common case".
if (getenv('PLATFORM_RELATIONSHIPS') && extension_loaded('memcached')) {
$relationships = json_decode(base64_decode(getenv('PLATFORM_RELATIONSHIPS')), TRUE);
// If you named your memcached relationship something other than "cache", set that here.
$relationship_name = 'cache';
if (!empty($relationships[$relationship_name])) {
// This is the line that tells Drupal to use memcached as a backend.
// Comment out just this line if you need to disable it for some reason and
// fall back to the default database cache.
$settings['cache']['default'] = 'cache.backend.memcache';
foreach ($relationships[$relationship_name] as $endpoint) {
$host = sprintf("%s:%d", $endpoint['host'], $endpoint['port']);
$settings['memcache']['servers'][$host] = 'default';
}
}
// By default Drupal starts the cache_container on the database. The following
// code overrides that.
// Make sure that the $class_load->addPsr4 is pointing to the right location of
// the memcache module. The value below should be correct if memcache was installed
// using Drupal Composer.
$memcache_exists = class_exists('Memcache', FALSE);
$memcached_exists = class_exists('Memcached', FALSE);
if ($memcache_exists || $memcached_exists) {
$class_loader->addPsr4('Drupal\\memcache\\', 'modules/contrib/memcache/src');
// If using a multisite configuration, adapt this line to include a site-unique
// value.
$settings['memcache']['key_prefix'] = getenv('PLATFORM_ENVIRONMENT');
// Define custom bootstrap container definition to use Memcache for cache.container.
$settings['bootstrap_container_definition'] = [
'parameters' => [],
'services' => [
'database' => [
'class' => 'Drupal\Core\Database\Connection',
'factory' => 'Drupal\Core\Database\Database::getConnection',
'arguments' => ['default'],
],
'settings' => [
'class' => 'Drupal\Core\Site\Settings',
'factory' => 'Drupal\Core\Site\Settings::getInstance',
],
'memcache.settings' => [
'class' => 'Drupal\memcache\MemcacheSettings',
'arguments' => ['@settings'],
],
'memcache.factory' => [
'class' => 'Drupal\memcache\Driver\MemcacheDriverFactory',
'arguments' => ['@memcache.settings'],
],
'memcache.backend.cache.container' => [
'class' => 'Drupal\memcache\DrupalMemcacheInterface',
'factory' => ['@memcache.factory', 'get'],
'arguments' => ['container'],
],
'lock.container' => [
'class' => 'Drupal\memcache\Lock\MemcacheLockBackend',
'arguments' => ['container', '@memcache.backend.cache.container'],
],
'cache_tags_provider.container' => [
'class' => 'Drupal\Core\Cache\DatabaseCacheTagsChecksum',
'arguments' => ['@database'],
],
'cache.container' => [
'class' => 'Drupal\memcache\MemcacheBackend',
'arguments' => ['container', '@memcache.backend.cache.container', '@lock.container', '@memcache.config', '@cache_tags_provider.container'],
],
],
];
}
}