setting up memcached in docker-compose to be used in drupal https://www.valuebound.com/resources/blog/configuring-memcache-drupal-8-to-reduce-database-load

docker-compose.yml

  memcached: 
    container_name:memcached 
    image: memcached:1.5
    restart: "no"
    ports:
    - 11211 
 

settings.php

$settings['cache']['default'] = 'cache.backend.memcache_storage';
// Set’s Memcache key prefix for your site and useful in working sites with same memcache as backend.
$settings['memcache_storage']['key_prefix'] = '';
// Set’s Memcache storage server’s.
$settings['memcache_storage']['memcached_servers'] =  ['memcached:11211' => 'default'];



# to debug memcached.

$settings['memcache_storage']['debug'] = TRUE;