Since the runtime may try to create mount points within
the sandbox, it will fail if the mount point is within
a read-only API data volume, like a secret or configMap
volume.
Create any needed mount points during volume setup.
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Rework method of updating atomic-updated data volumes
**What this PR does / why we need it**:
This change affects the way that secret, configmap, downwardAPI and projected volumes (which all use the same underlying code) implement their data update functionality.
* Instead of creating a subdirectory hierarchy that will contain symlinks to each actual data file, create only symlinks to items in the root of the volume, whether they be files or directories.
* Rather than comparing the user-visible data directory to see if an update is needed, compare with the current version of the data directory.
* Fix data dir timestamp format year
* Create `..data` symlink even when a data volume has no data so consumers can have simplified update watch logic.
**Which issue(s) this PR fixes**:
Fixes#57421
**Release note**:
```release-note
Correct issues that arise when volumes are mounted beneath another secret, configmap, downwardAPI or projected volume
```
This change affects the way that secret, configmap, downwardAPI and projected
volumes (which all use the same underlying code) implement their data update
functionality.
* Instead of creating a subdirectory hierarchy that itself
will contain symlinks to each actual data file, create only
symlinks to items in the root of the volume, whether they
be files or directories.
* Rather than comparing the user-visible data directory
to see if an update is needed, compare with the current
version of the data directory.
* Fix data dir timestamp format year
* Create ..data symlink even when a data volume has no data so
consumers can have simplified update watch logic.
This implements Bulk volume polling using ideas presented by
justin in https://github.com/kubernetes/kubernetes/pull/39564
But it changes the implementation to use an interface
and doesn't affect other implementations.
Joel Smith