memcached.md

Memcached

A plain in-memory cache server, off by default. Enable it when the application expects Memcached specifically — Magento session storage, a legacy PrestaShop or WooCommerce cache backend, a framework whose driver list has no Redis.

For anything new, prefer Redis or Valkey: they cover the same ground, madock already ships them, and they persist. Memcached is here for the code that asks for it by name.

To enable the service execute the command:

madock service:enable memcached

To disable it:

madock service:disable memcached

Both commands rebuild the project. Enabling it also rebuilds the PHP image, because the php-memcached extension is installed only while the service is on.

Configuration

• Host: memcached
• Port: 11211

The port is not published to the host — the container is reachable from the other containers of the project by the service name.

Version and memory

madock config:set --name memcached/repository --value memcached

madock config:set --name memcached/version --value 1.6.39-alpine

Cache size in megabytes (-m), 256 by default:

madock config:set --name memcached/memory --value 512

Maximum simultaneous connections (-c), 1024 by default:

madock config:set --name memcached/max_connections --value 2048

service:enable memcached also accepts the version directly, skipping the interactive picker:

madock service:enable memcached --service-version 1.6.39-alpine

After any configuration change, rebuild the project:

madock rebuild

PHP extension

php{version}-memcached is installed into the PHP image while the service is enabled, and left out otherwise. The install is tolerant of a missing package — ondrej's repository lags a release or two behind for the newest PHP versions, and a hard failure there would break the image build for everyone. If php -m does not list memcached after a rebuild, that package is not published for your PHP version yet; pin an older PHP version or wait for the repository to catch up.

Note that PHP has two separate extensions: memcached (libmemcached-based, what madock installs, what Magento uses) and the older memcache. They are not interchangeable.

Magento example

Session storage in app/etc/env.php:

'session' => [
    'save' => 'memcached',
    'save_path' => 'memcached:11211',
],

Isolation mode

With isolation/enabled the container joins the isolated network alongside the rest of the stack, so nothing outside the project can reach it. See Isolation mode.