docker volume prune: Dont delete named volumes - docker

Question

I have created a volume
docker volume create postgresql_db
Now i am using it in my docker-compose.xml
services:
postgresql:
image: "postgres:11-alpine"
volumes:
- type: volume
source: postgresql_data
target: /var/lib/postgresql/data
volume:
nocopy: true
environment:
PGDATA: '/var/lib/postgresql/data/pgdata'
networks: # connect to the bridge
- postgresql_network
command: ["postgres", "-c", "log_statement=all","-c", "log_destination=stderr"]
volumes:
postgresql_data:
external: true
Sometimes i want to stop and clean the docker system.
So I try to run
docker stop $(docker ps -aq) # stop all containers
docker rm $(docker ps -a -q) # remove all containers
docker container prune
docker image prune
docker network prune
docker volume prune #<-- remove all dangling volumes also
this also delete postgresql_data i.e named volume
how to avoid that.

Answer 1

Well, according to Docker's documentation, you can simply filter your volumes (by label, for instance):
docker volume prune --filter label!=postgresql_db
then all volumes that are not (look at the !) named postgresql_db and are not attached to 1 or more containers will be removed.

Answer 2

There's no option to the docker volume prune command for this. There's also no metadata on the volume that indicates it's an anonymous volume, it's just a named volume with a random hex name. The best I do is list the dangling volumes and delete the ones with a long hex name. As long as your named volumes are not exactly 64 hex characters, they won't be included in this:
docker volume ls -qf dangling=true | egrep '^[a-z0-9]{64}$' | \
xargs --no-run-if-empty docker volume rm

Answer 3

It worked for me.
Delete all unnamed volumes:
docker volume prune --filter "label!=com.docker.compose.volume"

Answer 4

docker rm offers the flag -v which is deleting all anonymous volumes corresponding to this container.
If you want to prune the dangling ones as well (not associated to any container you're currently running) do the docker volume prune before stopping and removing the running ones.
Therefore:
docker volume prune #<-- remove all dangling volumes also
docker stop $(docker ps -aq) # stop all containers
docker rm -v $(docker ps -a -q) # remove all containers
docker container prune
docker image prune
docker network prune