According to the docs there is a 'inmemory' driver for docker volumes: https://docs.docker.com/registry/storage-drivers/inmemory/
For purely tests purposes, you can use the inmemory storage driver. This driver is an implementation of the storagedriver.StorageDriver interface which uses local memory for object storage.
But when trying to use it like so:
volumes:
ui-tmp-memory:
driver: inmemory
It gives me this output:
Creating volume "myapp_ui-tmp-memory" with inmemory driver
ERROR: Volume ui-tmp-memory specifies nonexistent driver inmemory
Am I missing something or do I need to install "inmemory" driver somehow?
The link you've provided points to storage drivers for Docker Registry. You seem to want to mount a volume in a container which would require a Docker Engine Volume Plugin. These are two distinct types of plugins for two different applications and aren't interchangeable.
You may be able to easily accomplish what you want by creating a RAM disk and using the Local Persist Plugin in Docker Engine.