The downside is the prune command is a giant hammer. In a lot of cases you don't want to clean everything, just things you know you won't be using. For instance, in a CI environment there's going to be some images that will always be there, but if you run a prune in-between jobs you've now made it necessary to re-pull all images.

If you're on Mac, it's still a bit of a problem; hopefully the SSD-gobbling Docker.qcow2 file problem[1] is fixed soon!

[1] https://github.com/docker/for-mac/issues/371

Looks like it is fixed in https://twitter.com/kelseyhightower/status/82223709949555097.... Im looking for official changelog for confirmation though.

Judging by the github issue list there are a lot more issues with Docker.qcow2 now than before. Mostly related to Docker.qcow2 preventing docker from starting.

Looks like a bad release. Hopefully 1.13.1 is soon.

(I work on Docker for Mac.)

Apologies for the inconvenience this has caused.

There was a race condition in a previous release which could allow multiple hypervisor instances to open the Docker.qcow2 simultaneously. Unfortunately this can corrupt the file by allocating the same physical block (cluster) twice, resulting in bad things happening. When this file-locking bug was fixed we also added an integrity check which checks the structure of the Docker.qcow2 on every application launch. For safety the app refuses to start if corruption is detected.

I believe that in these cases, the corruption happened in the past and is now being detected since the upgrade. Unfortunately if the app refuses to start it makes it difficult to reach the "Reset to Factory defaults" menu option. The workaround described here https://github.com/docker/for-mac/issues/1159#issuecomment-2... is to remove the qcow2 and restart the app. Unfortunately containers and images will need to be rebuilt.

For what it's worth after the integrity check and the locking fix went in, I've not seen any recurrence of this error. Please open an issue if you see any other problems!

This is now fixed on the stable release, but space is only released when you restart docker at present. Online freeing is being worked on too.

I have a little one-liner I keep around on all my docker hosts that does this for me. I don't think you needed to wait for them to add anything.

    #!/usr/bin/env bash
    docker rmi $(docker images --filter "dangling=true" -q --no-trunc)

Yes and isn't it fun to type that in over and over - especially on a new machine where you don't have your .dotfiles yet :-/ The new command is going to really save hassle here.

The new command is definitely a nice addition, but I can't say that I've manually ran the other clean up commands in a long time. They were sitting in a daily cron for the last 9 months or so.