truly persistent volumes

[JohnRDOrazio]

Named volumes created in docker compose are not actually truly persistent, they will be removed by docker compose down. This is an alternative method to create truly persistent volumes that will not be removed by docker compose down.

[DavidMStraub]

I never had any volumes deleted by this command and this is not the intended behaviour according to the docker documentation. So I don't think this is needed. Or can you point to docker documentation of this behaviour?

[JohnRDOrazio]

https://docs.docker.com/reference/cli/docker/compose/down/

docker compose down

Stops containers and removes containers, networks, volumes, and images created by up.
Networks and volumes defined as external are never removed.

It does also state that volumes are not removed by default unless the -v flag is used. However I have had volumes removed on more than one occasion. It might have something to do with other environment settings that change the defaults, I'm not sure.

In any case, defining a volume as external is a safer bet.