CSI: node unmount from the client before unpublish RPC #11892
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
tgross
changed the title
tgross
force-pushed
the
csi-client-side-node-unmount
branch
from
c28c1bd to
28ed20d
Compare
This was referenced Jan 25, 2022
jrasell
approved these changes
Jan 27, 2022
client/allocrunner/csi_hook.go
Outdated
Comment on lines
111
to
113
| if err != nil { | ||
| mErr = multierror.Append(mErr, err) | ||
| } |
There was a problem hiding this comment.
Apologies if this was covered yesterday, but for my education, if we fail to unmount the volume, can attempting to unpublish the volume succeed or will it always fail? I am curious how the fall-through when an error is received works.
There was a problem hiding this comment.
Good catch. There are two cases:
- We may be returning an error that's
structs.ErrCSIClientRPCIgnorable. For example, this CSI RPC is supposed to be idempotent so if it's been node-unpublished already we still want to make theCSIVolume.UnpublishRPC back to the server so that the server can do a controller-unpublish and release the claim. - If it's not ignorable (ex. the node plugin's alloc is gone), we should probably not send the
CSIVolume.Unpublishbecause there's nothing we can do from the server that will improve things! Instead we should be retrying until it works with exponential backoff, and logging that so that the operator can intervene manually. That will cause alloc shutdown to hang, which I think is exactly what we want here.
That being said, I think we should push the "ignorable" errors down into the UnmountVolume so that we only ever return non-ignorable errors. Then this code can just have a happy path and a path where errors need to be retried and block this method from returning.
There was a problem hiding this comment.
@jrasell I've addressed this in 04f5b7a:
The CSI
NodeUnpublishVolume/NodeUnstageVolumeRPCs can return
ignorable errors in the case where the volume has already been
unmounted from the node. Handle all other errors by retrying until we
get success so as to give operators the opportunity to reschedule a
failed node plugin (ex. in the case where they accidentally drained a
node without-ignore-system). Fan-out the work for each volume into
its own goroutine so that we can release a subset of volumes if only
one is stuck.
When an allocation stops, the `csi_hook` makes an unpublish RPC to the servers to unpublish via the CSI RPCs: first to the node plugins and then the controller plugins. The controller RPCs must happen after the node RPCs so that the node has had a chance to unmount the volume before the controller tries to detach the associated device. But the client has local access to the node plugins and can independently determine if it's safe to send unpublish RPC to those plugins. This will allow the server to treat the node plugin as abandoned if a client is disconnected and `stop_on_client_disconnect` is set. This will let the server try to send unpublish RPCs to the controller plugins, under the assumption that the client will be trying to unmount the volume on its end first.
tgross
force-pushed
the
csi-client-side-node-unmount
branch
from
28ed20d to
04f5b7a
Compare
The CSI `NodeUnpublishVolume`/`NodeUnstageVolume` RPCs can return ignorable errors in the case where the volume has already been unmounted from the node. Handle all other errors by retrying until we get success so as to give operators the opportunity to reschedule a failed node plugin (ex. in the case where they accidentally drained a node without `-ignore-system`). Fan-out the work for each volume into its own goroutine so that we can release a subset of volumes if only one is stuck.
tgross
force-pushed
the
csi-client-side-node-unmount
branch
from
04f5b7a to
3b7dedb
Compare
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
When an allocation stops, the `csi_hook` makes an unpublish RPC to the servers to unpublish via the CSI RPCs: first to the node plugins and then the controller plugins. The controller RPCs must happen after the node RPCs so that the node has had a chance to unmount the volume before the controller tries to detach the associated device. But the client has local access to the node plugins and can independently determine if it's safe to send unpublish RPC to those plugins. This will allow the server to treat the node plugin as abandoned if a client is disconnected and `stop_on_client_disconnect` is set. This will let the server try to send unpublish RPCs to the controller plugins, under the assumption that the client will be trying to unmount the volume on its end first. Note that the CSI `NodeUnpublishVolume`/`NodeUnstageVolume` RPCs can return ignorable errors in the case where the volume has already been unmounted from the node. Handle all other errors by retrying until we get success so as to give operators the opportunity to reschedule a failed node plugin (ex. in the case where they accidentally drained a node without `-ignore-system`). Fan-out the work for each volume into its own goroutine so that we can release a subset of volumes if only one is stuck.
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
When an allocation stops, the `csi_hook` makes an unpublish RPC to the servers to unpublish via the CSI RPCs: first to the node plugins and then the controller plugins. The controller RPCs must happen after the node RPCs so that the node has had a chance to unmount the volume before the controller tries to detach the associated device. But the client has local access to the node plugins and can independently determine if it's safe to send unpublish RPC to those plugins. This will allow the server to treat the node plugin as abandoned if a client is disconnected and `stop_on_client_disconnect` is set. This will let the server try to send unpublish RPCs to the controller plugins, under the assumption that the client will be trying to unmount the volume on its end first. Note that the CSI `NodeUnpublishVolume`/`NodeUnstageVolume` RPCs can return ignorable errors in the case where the volume has already been unmounted from the node. Handle all other errors by retrying until we get success so as to give operators the opportunity to reschedule a failed node plugin (ex. in the case where they accidentally drained a node without `-ignore-system`). Fan-out the work for each volume into its own goroutine so that we can release a subset of volumes if only one is stuck.
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
When an allocation stops, the `csi_hook` makes an unpublish RPC to the servers to unpublish via the CSI RPCs: first to the node plugins and then the controller plugins. The controller RPCs must happen after the node RPCs so that the node has had a chance to unmount the volume before the controller tries to detach the associated device. But the client has local access to the node plugins and can independently determine if it's safe to send unpublish RPC to those plugins. This will allow the server to treat the node plugin as abandoned if a client is disconnected and `stop_on_client_disconnect` is set. This will let the server try to send unpublish RPCs to the controller plugins, under the assumption that the client will be trying to unmount the volume on its end first. Note that the CSI `NodeUnpublishVolume`/`NodeUnstageVolume` RPCs can return ignorable errors in the case where the volume has already been unmounted from the node. Handle all other errors by retrying until we get success so as to give operators the opportunity to reschedule a failed node plugin (ex. in the case where they accidentally drained a node without `-ignore-system`). Fan-out the work for each volume into its own goroutine so that we can release a subset of volumes if only one is stuck.
tgross
added a commit
that referenced
this pull request
Jan 28, 2022
This was referenced Feb 3, 2022
tgross
added a commit
that referenced
this pull request
Feb 22, 2022
In PR #11892 we updated the `csi_hook` to unmount the volume locally via the CSI node RPCs before releasing the claim from the server. The timer for this hook was initialized with the retry time, forcing us to wait 1s before making the first unmount RPC calls. Use the new helper for timers to ensure we clean up the timer nicely.
tgross
added a commit
that referenced
this pull request
Feb 22, 2022
In PR #11892 we updated the `csi_hook` to unmount the volume locally via the CSI node RPCs before releasing the claim from the server. The timer for this hook was initialized with the retry time, forcing us to wait 1s before making the first unmount RPC calls. Use the new helper for timers to ensure we clean up the timer nicely.
This was referenced Mar 18, 2022
tgross
added a commit
that referenced
this pull request
Apr 5, 2022
When we unmount a volume we need to be able to recover from cases where the plugin has been shutdown before the allocation that needs it, so in #11892 we blocked shutting down the alloc runner hook. But this blocks client shutdown if we're in the middle of unmounting. The client won't be able to communicate with the plugin or send the unpublish RPC anyways, so we should cancel the context and assume that we'll resume the unmounting process when the client restarts. For `-dev` mode we don't send the graceful `Shutdown()` method and instead destroy all the allocations. In this case, we'll never be able to communicate with the plugin but also never close the context we need to prevent the hook from blocking. To fix this, move the retries into their own goroutine that doesn't block the main `Postrun`.
tgross
added a commit
that referenced
this pull request
Apr 5, 2022
When we unmount a volume we need to be able to recover from cases where the plugin has been shutdown before the allocation that needs it, so in #11892 we blocked shutting down the alloc runner hook. But this blocks client shutdown if we're in the middle of unmounting. The client won't be able to communicate with the plugin or send the unpublish RPC anyways, so we should cancel the context and assume that we'll resume the unmounting process when the client restarts. For `-dev` mode we don't send the graceful `Shutdown()` method and instead destroy all the allocations. In this case, we'll never be able to communicate with the plugin but also never close the context we need to prevent the hook from blocking. To fix this, move the retries into their own goroutine that doesn't block the main `Postrun`.
This was referenced Apr 19, 2022
|
I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions. |
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Partial fix for #10927 #10052 #10833
Requires #11890 #11932
When an allocation stops, the
csi_hookmakes an unpublish RPC to theservers to unpublish via the CSI RPCs: first to the node plugins and
then the controller plugins. The controller RPCs must happen after the
node RPCs so that the node has had a chance to unmount the volume
before the controller tries to detach the associated device.
But the client has local access to the node plugins and can
independently determine if it's safe to send unpublish RPC to those
plugins. This will allow the server to treat the node plugin as
abandoned if a client is disconnected and
stop_on_client_disconnectis set. This will let the server try to send unpublish RPCs to the
controller plugins, under the assumption that the client will be
trying to unmount the volume on its end first.