I've noticed that from time to time, the container storage volume seems
to accumulate "dangling" containers. These are paths under
`/var/lib/containers/storage/overlay` that have a bunch of content in
their `diff` sub-directory, but nothing else, and do not seem to be
mounted into any running containers. I have not identified what causes
this, nor a simple and reliable way to clean them up. Fortunately,
wiping the entire container storage graph with `crio wipe` seems to work
well enough.
The `crio-clean.sh` script takes care of safely wiping the container
storage graph on a given node. It first drains the node and then stops
any running containers that were left. Then, it uses `crio wipe` to
clean the entire storage graph. Finally, it restarts the node, allowing
Kubernetes to reschedule the pods that were stopped.
