Memcached

The Wodby Memcached catalog stack runs a single Memcached service. The current composition and defaults are documented in wodby/stack-memcached.

Connect an application

The service listens on TCP port 11211. UDP is switched off. It has no HTTP endpoint, so Wodby creates no route for it.

Link your application's app service to the Memcached app service. See Links. The app service receives the host and port in variables named by the linking service. Read them in code instead of hardcoding the host.

Memcached has no password, and Wodby generates no token for it. Access is limited to the environment's internal network.

Settings

Change these under Configuration > Settings on the Memcached app service. Do not use a command or a configuration file.

Setting	Variable	Default
Cache memory (MB)	MEMCACHED_MEMORY	64
Worker threads	MEMCACHED_THREADS	4
Maximum connections	MEMCACHED_MAX_CONNECTIONS	1024

Cache memory (MB) covers cached items only. The process uses more, so set the container memory limit higher under Runtime > Resources.

Data loss

Memcached stores nothing on disk, and the service has no volume. Every restart and every deployment empties the cache, because the service is replaced rather than updated in place. When the item memory is full, Memcached evicts the least recently used items. Do not keep data here that you cannot rebuild.

Check that it works

Open a web terminal on the Memcached app service and run:

make check-ready -f /usr/local/bin/actions.mk
printf 'stats\r\nquit\r\n' | nc localhost 11211

The first command reports whether the server answers. The second shows limit_maxbytes, curr_items and evictions.