Does Kubernetes mount an emtpyDir volume on the host? - kubernetes

Question

Kubernetes features quite a few types of volumes, including emptyDir:
An emptyDir volume is first created when a Pod is assigned to a Node, and exists as long as that Pod is running on that node. As the name says, it is initially empty. Containers in the pod can all read and write the same files in the emptyDir volume, though that volume can be mounted at the same or different paths in each container. When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever.
...
By default, emptyDir volumes are stored on whatever medium is backing the node.
Is the emtpyDir actually mounted on the node, and accessible to a container outside the pod, or to the node FS itself?

Answer 1

Yes it is also accessible on the node. It is bind mounted into the container (sort of). The source directories are under /var/lib/kubelet/pods/PODUID/volumes/kubernetes.io~empty-dir/VOLUMENAME
You can find the location on the host like this:
sudo ls -l /var/lib/kubelet/pods/`kubectl get pod -n mynamespace mypod -o 'jsonpath={.metadata.uid}'`/volumes/kubernetes.io~empty-dir

Answer 2

You can list all emptyDir volumes on the host using this command
df
To view only volumes mapped to a specific volume
df | grep -i cache-volume
where cache-volume is the volume name in your pod definition
apiVersion: v1
kind: Pod
metadata:
name: test-pd
spec:
containers:
- image: k8s.gcr.io/test-webserver
name: test-container
volumeMounts:
- mountPath: /cache
name: cache-volume
volumes:
- name: cache-volume
emptyDir: {}