✨ Remove not used anonymous volumes too

[LeSpocky]

change

Some containers (e.g. mariadb in default configuration) make use of volumes managed by Docker (see docker volume command). Old volumes not used by containers might pile up and eat storage. Remove those, too.

Compare output of docker system prune when called with or without --volumes option:

% docker system prune --all
WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container 
  - all images without at least one container associated to them 
  - all build cache

Notice the additional line when calling with the option:

% docker system prune --all --volumes
WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container 
  - all anonymous volumes not used by at least one container 
  - all images without at least one container associated to them 
  - all build cache

discussion

Not sure if this should be squashed into the existing command which is controlled with docker_image_prune or if we should introduce a separate variable for pruning volumes only? Opinions?

[penguineer]

IMHO this should definitely be a distinct command/configuration, if not even a distinct (clean-up) role.

1. Images can usually recovered by downloading them again. There is usually no data loss when an image is deleted even though it might be needed later on. In contrast, deleting a volume leads to data loss and doing so in a CRON job might delete data without the user's consent.
2. Dangling images are part of normal operations, as software is frequently updated and old versions are no longer needed. Dangling volumes are part of development efforts and not "business as usual" for a docker environment.

[LeSpocky]

Okay thanks for your thoughts. Makes sense.