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 ensures that `flockerMounter.updateDatasetPrimary` does not leak
running `time.Ticker` instances. Upon termination of the consuming
routine, we stop the tickers.
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.
- Add volume.MetricsProvider function to Volume interface.
- Add volume.MetricsDu for providing metrics via executing "du".
- Add volulme.MetricsNil for unsupported Volumes.
Flocker [1] is an open-source container data volume manager for
Dockerized applications.
This PR adds a volume plugin for Flocker.
The plugin interfaces the Flocker Control Service REST API [2] to
attachment attach the volume to the pod.
Each kubelet host should run Flocker agents (Container Agent and Dataset
Agent).
The kubelet will also require environment variables that contain the
host and port of the Flocker Control Service. (see Flocker architecture
[3] for more).
- `FLOCKER_CONTROL_SERVICE_HOST`
- `FLOCKER_CONTROL_SERVICE_PORT`
The contribution introduces a new 'flocker' volume type to the API with
fields:
- `datasetName`: which indicates the name of the dataset in Flocker
added to metadata;
- `size`: a human-readable number that indicates the maximum size of the
requested dataset.
Full documentation can be found docs/user-guide/volumes.md and examples
can be found at the examples/ folder
[1] https://clusterhq.com/flocker/introduction/
[2] https://docs.clusterhq.com/en/1.3.1/reference/api.html
[3] https://docs.clusterhq.com/en/1.3.1/concepts/architecture.html
Jing Xu