Memcached

A simpler cache than Redis: keys and values, nothing else, and nothing kept when it restarts. Choose it when your application or a module you use speaks Memcached and nothing else; otherwise Valkey does the same job and more. A stack runs one cache — Memcached, Redis or Valkey — so naming a different one replaces it.

Inside the stack it answers at the hostname memcached, on port 11211. Unlike Redis and Valkey, no variable in your environment names it.

How much memory it holds is sized from your machine: most of a cache machine when it has one to itself, a share of your plan when it sits beside your site. It is not a setting, so a cache can never grow into the memory your site needs.

#Versions

A deprecated version still runs and is still what some sites are on. It is listed so you can move before it goes, rather than finding out on the morning a build stops resolving it.

Pin the version, not the build: name 1.6 and the platform matches it to the current build, so a security rebuild reaches you without anybody editing a repository.

#What you can change

Nothing on this one. Everything it takes decides where it connects, what it is, or whether it starts — and an application able to set those could break its own environment in ways nothing here would catch.