At master volume reconciler, the information about which volumes are
attached to nodes is cached in actual state of world. However, this
information might be out of date in case that node is terminated (volume
is detached automatically). In this situation, reconciler assume volume
is still attached and will not issue attach operation when node comes
back. Pods created on those nodes will fail to mount.
This PR adds the logic to periodically sync up the truth for attached volumes kept in the actual state cache. If the volume is no longer attached to the node, the actual state will be updated to reflect the truth. In turn, reconciler will take actions if needed.
To avoid issuing many concurrent operations on cloud provider, this PR
tries to add batch operation to check whether a list of volumes are
attached to the node instead of one request per volume.
More details are explained in PR #33760
When volume is attached, it is possible that the actual state
already has this volume object (e.g., the volume is attached to multiple
nodes, or volume was detached and attached again). We need to update the
device path in such situation, otherwise, the device path would be stale
information and cause kubelet mount to the wrong device.
This PR partially fixes issue #29324
We had another bug where we confused the hostname with the NodeName.
To avoid this happening again, and to make the code more
self-documenting, we use types.NodeName (a typedef alias for string)
whenever we are referring to the Node.Name.
A tedious but mechanical commit therefore, to change all uses of the
node name to use types.NodeName
Also clean up some of the (many) places where the NodeName is referred
to as a hostname (not true on AWS), or an instanceID (not true on GCE),
etc.
This PR fixes the race condition in setting node statusUpdateNeeded flag
in master's attachdetach controller. This flag is used to indicate
whether a node status has been updated by the node_status_updater or
not. When updater finishes update a node status, it is set to false.
When the node status is changed such as volume is detached or new volume
is attached to the node, the flag is set to true so that updater can
update the status again. The previous workflow has a race condition as
follows
1. updater gets the currently attached volume list from the node which needs to be
updated.
2. A new volume A is attached to the same node right after 1 and set the
flag to TRUE
3. updater updates the node attached volume list (which does not include volume A) and then set the flag to FALSE.
The result is that volume A will be never added to the attached volume
list so at node side, this volume is never attached.
So in this PR, the flag is set to FALSE when updater tries to get the
attached volume list (as in an atomic operation). So in the above
example, after step 2, the flag will be TRUE again, in step 3, updater
does not set the flag if updates is sucessful. So after that, flag is
still TRUE and in next round of update, the node status will be updated.
This PR also changes a unit test due to the workflow changes
This PR tries to fix issue #29324. This cause of this issue is a race
condition happens when marking volumes as attached for node status. This
PR tries to clean up the logic of when and where to mark volumes as
attached/detached. Basically the workflow as follows,
1. When volume is attached sucessfully, the volume and node info is
added into nodesToUpdateStatusFor to mark the volume as attached to the
node.
2. When detach request comes in, it will check whether it is safe to
detach now. If the check passes, remove the volume from volumesToReportAsAttached
to indicate the volume is no longer considered as attached now.
Afterwards, reconciler tries to update node status and trigger detach
operation. If any of these operation fails, the volume is added back to
the volumesToReportAsAttached list showing that it is still attached.
These steps should make sure that kubelet get the right (might be
outdated) information about which volume is attached or not. It also
garantees that if detach operation is pending, kubelet should not
trigger any mount operations.
This PR is to add event message when attaching volume fails to help
users to debug. For detach failure, may address in a different PR since
it requires more data structure change.
For non-attachable volumes, do not call GetVolumeName on the plugin and instead
generate a unique name based on the identity of the pod and the name of the volume
within the pod.
