How to remove unnamed volumes when docker compose down? - docker

Question

I have a docker-compose file which describes several services. All services have volumes attached to them, however only one has the volume named. When I run docker compose down I want to automatically delete the not named volumes while at the same time create all volumes that are missing.
services:
service1:
image: some/image:1
volumes:
- named-volume:/home/user1
service2:
image: some/image:2
#volumes: not declared volumes that are named automatically with a hash
volumes:
named-volume:
name: volume-for-service1
The first time I run docker compose up I want to automatically create all volumes (named and unnamed) and when I run docker compose down I want that unnamed volumes to be deleted while the named one (volume-for-service1) to be preserved. Next time I run docker compose up it should only create the unnamed volumes as the named one already exists.
I have tried:
docker compose down -v which removed no volume
docker compose down --remove-orphans which removed no volume
docker compose down --rmi local which removed no volume
docker-compose down -v which removed the named volume
docker-compose down --remove-orphans which removed no volume
docker-compose down --rmi local which removed no volume
OS: Windows 10 x64
I don't quite get it. What command should I run to achieve desired results?

Answer 1

Try using --renew-anon-volumes flag when bringing up the services
and use --volumes when bringing down the services
> docker-compose --renew-anon-volumes up
> docker-compose --volumes down
Refer the docker compose documentation
-V, --renew-anon-volumes Recreate anonymous volumes instead of retrieving
data from the previous containers.
-v, --volumes Remove named volumes declared in the `volumes`
section of the Compose file and anonymous volumes
attached to containers.
https://docs.docker.com/compose/reference/down/

Answer 2

To prevent removing named volumes, you should define them as external in the config file:
volumes:
volume-for-service1:
name: volume-for-service1
external: true
But you have to initially create them outside the config file somewhere else, either through:
docker volume create volume-for-service-1
or in a separate config file.
Reference: https://docs.docker.com/compose/compose-file/#external-1

Answer 3

I'm not aware of a way to remove unnamed volumes automatically, but you can match its hash and remove it with a small script.
To reuse your docker-compose.yml example, first you get the container name given the service name with:
docker-compose ps service2 # this is the one with unnamed volume in your example
Output could be something like:
NAME COMMAND SERVICE STATUS
project-service2-1 "docker-entrypoint.s…" service2 exited (0)
Then using the container name you can find its unamed volume hash:
docker inspect -f '{{ (index .Mounts 0).Name }}' project-service2-1
Now before deleting the volume you need to bring the container down or the volume would be in use.
docker-compose down
docker volume rm $volume # replace the "volume" var with the inspect output
Now that we saw the steps, let's try to make it a little script (slightly adjusted):
service_name=service2 # set the variable accordingly
container_id=$(docker-compose ps $service_name --quiet)
volume_name=$(docker inspect -f '{{ (index .Mounts 0).Name }}' $container_id)
docker-compose down
docker volume rm -f $volume_name