on debian, ''docker.io'' is docker "the debian way" - i.e., dependencies are shareable packages.
====== do not attempt to move docker directory ======
===== Method 1: -g =====
[[https://linuxconfig.org/how-to-move-docker-s-default-var-lib-docker-to-another-directory-on-ubuntu-debian-linux|from]]
you can set the docker directory to another one - but only if that alternate **is also on the same filesystem**. (begging the question: why even bother?)
- stop your shit
$ sudo systemctl stop docker.socket
$ sudo systemctl stop docker.service
- edit ''/lib/systemd/system/docker.service'' - find ''ExecStart='' and put a ''-g
ExecStart=/usr/bin/dockerd -g /new/path/docker -H fd://
- prepare that directory. make sure it exists, has the permissions you expect (probably want to ''chown -R :docker'' on it)
- reload, restart
$ sudo systemctl daemon-reload
$ sudo systemctl start docker
- test
ps aux | grep -i docker | grep -v grep
you should see the -g you added. then you can go into the directory and make sure docker put all its shit there.
===== Method 2: rmount =====
[[https://www.ibm.com/docs/en/cloud-private/3.1.0?topic=pyci-specifying-default-docker-storage-directory-by-using-bind-mount|from]]
you can __r__ecursively __mount__ any linux directory in any other - but docker trips over not being allowed to create hard links, and fails.