This allows users to diagnose what's wrong with recycler. Recycler pods are
started automatically with a cryptic name and they are deleted immediately
when they finish.
kubectl describe pods will show:
FirstSeen LastSeen Count From SubobjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
59m 59m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(5421800e-347b-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
53m 53m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(3c9809e5-347c-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
46m 46m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(250dd2a2-347d-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
40m 40m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(0d84ea33-347e-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
33m 33m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(f5fb63bf-347e-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
27m 27m 1 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Unable to mount volumes for pod "recycler-for-nfs_default(de7128fd-347f-11e6-a79b-3c970e965218)": timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
1h 3m 75 {persistentvolume-controller } Normal RecyclerPod Recycler pod: Successfully assigned recycler-for-nfs to 127.0.0.1
1h 3m 76 {persistentvolume-controller } Normal RecyclerPod Recycler pod: Pod was active on the node longer than specified deadline
1h 1m 12 {persistentvolume-controller } Warning RecyclerPod Recycler pod: Error syncing pod, skipping: timeout expired waiting for volumes to attach/mount for pod "recycler-for-nfs"/"default". list of unattached/unmounted volumes=[vol]
20m 1m 4 {persistentvolume-controller } Warning RecyclerPod (events with common reason combined)
These steps were necessary:
- added event watcher to volume.RecycleVolumeByWatchingPodUntilCompletion
- pass all these events through volume plugins to volume controller
- rework volume.RecycleVolumeByWatchingPodUntilCompletion unit tests to a table
(too much copy-paste)
- fix all unit tests along the way
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 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.
Recycling is a long duration process and when the recycler controller is
restarted in the meantime, it should not start a new recycler pod if there is
one already running.
This means that the recycler pod must have deterministic name based on name
of the recycled PV, we then get name conflicts when creating the pod.
Two things need to be changed:
- recycler controller and recycler plugins must pass the PV.Name to place,
where the pod is created.
- create recycler pod with deterministic name and check "already exists" error.
When at it, remove useless 'resourceVersion' argument and make log messages
starting with lowercase.
- Add volume.MetricsProvider function to Volume interface.
- Add volume.MetricsDu for providing metrics via executing "du".
- Add volulme.MetricsNil for unsupported Volumes.
IsLikelyNotMountPoint determines if a directory is not a mountpoint.
It is fast but not necessarily ALWAYS correct. If the path is in fact
a bind mount from one part of a mount to another it will not be detected.
mkdir /tmp/a /tmp/b; mount --bin /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
will return true. When in fact /tmp/b is a mount point. So this patch
renames the function and switches it from a positive to a negative (I
could think of a good positive name). This should make future users of
this function aware that it isn't quite perfect, but probably good
enough.
