This commit adds a new volume manager in kubelet that synchronizes
volume mount/unmount (and attach/detach, if attach/detach controller
is not enabled).
This eliminates the race conditions between the pod creation loop
and the orphaned volumes loops. It also removes the unmount/detach
from the `syncPod()` path so volume clean up never blocks the
`syncPod` loop.
This PR contains Kubelet changes to enable attach/detach controller control.
* It introduces a new "enable-controller-attach-detach" kubelet flag to
enable control by controller. Default enabled.
* It removes all references "SafeToDetach" annoation from controller.
* It adds the new VolumesInUse field to the Node Status API object.
* It modifies the controller to use VolumesInUse instead of SafeToDetach
annotation to gate detachment.
* There is a bug in node-problem-detector that causes VolumesInUse to
get reset every 30 seconds. Issue https://github.com/kubernetes/node-problem-detector/issues/9
opened to fix that.
Automatic merge from submit-queue
Extend secrets volumes with path control
As per [1] this PR extends secrets mapped into volume with:
* key-to-path mapping the same way as is for configmap. E.g.
```
{
"apiVersion": "v1",
"kind": "Pod",
"metadata": {
"name": "mypod",
"namespace": "default"
},
"spec": {
"containers": [{
"name": "mypod",
"image": "redis",
"volumeMounts": [{
"name": "foo",
"mountPath": "/etc/foo",
"readOnly": true
}]
}],
"volumes": [{
"name": "foo",
"secret": {
"secretName": "mysecret",
"items": [{
"key": "username",
"path": "my-username"
}]
}
}]
}
}
```
Here the ``spec.volumes[0].secret.items`` added changing original target ``/etc/foo/username`` to ``/etc/foo/my-username``.
* secondly, refactoring ``pkg/volumes/secrets/secrets.go`` volume plugin to use ``AtomicWritter`` to project a secret into file.
[1] https://github.com/kubernetes/kubernetes/blob/master/docs/design/configmap.md#changes-to-secret
Automatic merge from submit-queue
Add subPath to mount a child dir or file of a volumeMount
Allow users to specify a subPath in Container.volumeMounts so they can use a single volume for many mounts instead of creating many volumes. For instance, a user can now use a single PersistentVolume to store the Mysql database and the document root of an Apache server of a LAMP stack pod by mapping them to different subPaths in this single volume.
Also solves https://github.com/kubernetes/kubernetes/issues/20466.
Jordan Liggitt