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.
Package goroutinemap can be structurally simplified to be more
idiomatic, concise, and free of error potential. No structural changes
are made.
It is unconventional declare `sync.Mutex` directly as a pointerized
field in a parent structure. The `sync.Mutex` operates on pointer
receivers of itself; and by relying on that, the types that contain
those fields can be safely constructed using
https://golang.org/ref/spec#The_zero_value.
The duration constants are already of type `time.Duration`, so
re-declaring that is redundant.
Allow mount volume operations to run in parallel for non-attachable
volume plugins.
Allow unmount volume operations to run in parallel for all volume
plugins.
Automatic merge from submit-queue
Fixed goroutinemap race on Wait()
sync.WaitGroup produces data races when a GoroutineMap is empty and Wait() and Run() are called at the same time.
From sync.WaitGroup:
> Note that calls with a positive delta that occur when the counter is zero must happen before a Wait.
Fixes#28128
Note that this issue affects only PersistentVolume unit tests.
@saad-ali, PTAL
sync.WaitGroup produces data races when a GoroutineMap is empty and Wait() and
Run() are called at the same time.
From sync.WaitGroup:
Note that calls with a positive delta that occur when the counter is zero
must happen before a Wait.
Fixes#28128
Modify attach/detach controller to keep track of volumes to report
attached in Node VolumeToAttach status.
Modify kubelet volume manager to wait for volume to show up in Node
VolumeToAttach status.
Implement exponential backoff for errors in volume manager and attach
detach controller
PersistentVolume controller needs to know why scheduling a new operation has
failed - if the operation was already running or some other error happened.
Paul Morie