This implements the proposal in:
docs/proposals/secret-configmap-downwarapi-file-mode.md
Fixes: #28317.
The mounttest image is updated so it returns the permissions of the linked file
and not the symlink itself.
Currently kubelet volume management works on the concept of desired
and actual world of states. The volume manager periodically compares the
two worlds and perform volume mount/unmount and/or attach/detach
operations. When kubelet restarts, the cache of those two worlds are
gone. Although desired world can be recovered through apiserver, actual
world can not be recovered which may cause some volumes cannot be cleaned
up if their information is deleted by apiserver. This change adds the
reconstruction of the actual world by reading the pod directories from
disk. The reconstructed volume information is added to both desired
world and actual world if it cannot be found in either world. The rest
logic would be as same as before, desired world populator may clean up
the volume entry if it is no longer in apiserver, and then volume
manager should invoke unmount to clean it up.
This fixes race conditions in configmap, secret, downwardapi & git_repo
volume plugins.
wrappedVolumeSpec vars used by volume mounters and unmounters contained
a pointer to api.Volume structs which were being patched by
NewWrapperMounter/NewWrapperUnmounter, causing race condition during
volume mounts.
This is to base the name on the volume not just on the
source configMap. If you have 2 volumes that both have the same
configMap as a source, the volume is see as being in the attached
state (it's state is looked up based on GetVolumeName()).
See bug #28502
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.
