Do not delete any files or folders inside /var/lib/docker unless you know what you are doing.
You can reclaim space using the docker cli:
If you build a lot of images, you can cleanup the build cache:
docker build prune
If you have a lot of orphaned images in your local image cache, you can clean them up by
docker image prune (if you feel bold, you cann add a
-a flag at the end to not only remove dangline images, but also every image not currently used by a container).
And finaly we have
docker system prune (if you feel brave, you can add the
-a flag at the end as well :))
And then there are container logs going wild… this needs to be fixed in the image!