Docker taking up too much space

Question

I am using Docker on Windows with WSL 2 backend. The hard disc image file on path C:\Users\me\AppData\Local\Docker\wsl\data is taking up 160 GB of disc space. I have tried the command:

Optimize -VHD -Path C:\Users\me\AppData\Local\Docker\wsl\data\disc.ext4 -Mode Full

but it only clears up a couple of MB.

I also tried to clean docker with docker prune but that doesn't help either.

I also tried modifying the .wslconfig file, but it turns out you can't set disc space usage that way, only RAM usage.

I am not sure why is it taking up so much space in the first place, considering I only have 5 containers and images. Any help/advice is highly appreciated.

Additional info:

docker image ls -a

... cumulatively shows only 2 or 3 GB taken.

docker container ls -a

... shows 5 containers.

docker info shows (I didnt copy and paste the whole output because it's too long):

Server:
 Containers: 5
  Running: 2
  Paused: 0
  Stopped: 3
 Images: 5
 Kernel Version: 5.4.72-microsoft-standard-WSL2
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 12.37GiB

Answer 1

You may have already resolved this but I came across this article that solved it for me: https://btburnett.com/docker/2021/09/06/reclaiming-hd-space-from-docker-desktop-on-wsl-2.html

The key thing here was the inclusion of a step to run a container (provided by Docker themselves) to send TRIM commands to the hardware abstraction layer:

docker run --rm --privileged --pid=host docker/desktop-reclaim-space

This process ensures that unused sectors are identified and allows Hyper-V to shrink the VHDX file further.