detach the volume when pod is terminated #45286

gnufied · 2017-05-03T14:25:38Z

When pods are terminated we should detach the volume.

Release note:

Detach the volume when pods are terminated.

k8s-reviewable · 2017-05-03T14:25:47Z

This change is

wongma7 · 2017-05-03T14:44:50Z

pkg/controller/volume/attachdetach/attach_detach_controller.go

@@ -395,8 +401,23 @@ func (adc *attachDetachController) GetDesiredStateOfWorld() cache.DesiredStateOf
 }

 func (adc *attachDetachController) podUpdate(oldObj, newObj interface{}) {


podUpdate still only happens once every 12 hours though right?

I think we have to do it in one of the reconciler loops

I would assume that, podUpdate should get called when pod's status for example, changes from Running to Complete - not every 12 hours.

Also, regardless of this event though - I have also updated DSWP to remove the pod from DSW if pod is terminated.

oh yeah...brain fart my b 🥇

luxas

Thanks for this PR!

General comment without having context on this particular feature -- is there any way we could implement this without adding yet another flag? We really need to ask ourselves that question, otherwise we'll end up with thousands of flags. Just something to keep in mind ;)

luxas · 2017-05-03T18:59:19Z

/unassign

childsb · 2017-05-03T19:02:38Z

@luxas the reason for the flag is to preserver backwards behavior, which in some cases may be desirable.

rootfs · 2017-05-03T19:06:47Z

pkg/controller/volume/attachdetach/attach_detach_controller.go

@@ -233,6 +236,9 @@ type attachDetachController struct {

 	// recorder is used to record events in the API server
 	recorder record.EventRecorder
+
+	// keep pod volumes attached for terminated pods


whether keep pod volumes

rootfs · 2017-05-03T19:09:27Z

pkg/controller/volume/attachdetach/attach_detach_controller.go

+		return
+	}
+
+	util.ProcessPodVolumes(pod, true, /* addVolumes */


nit: make a boolean variable instead of calling ProcessPodVolumes twice with mostly the same parameters.

rootfs · 2017-05-03T19:09:47Z

pkg/controller/volume/attachdetach/attach_detach_controller_test.go

@@ -46,7 +46,8 @@ func Test_NewAttachDetachController_Positive(t *testing.T) {
 		nil, /* cloud */
 		nil, /* plugins */
 		false,
-		time.Second*5)
+		time.Second*5,
+		false /*keep pod volumes attached for terminated pods */)


whether keep pod volumes...

You mean change wording to /* whether keep pod volumes */ ?

rootfs · 2017-05-03T19:13:06Z

cmd/kube-controller-manager/app/options/options.go

@@ -211,6 +212,7 @@ func (s *CMServer) AddFlags(fs *pflag.FlagSet, allControllers []string, disabled
 	fs.Int32Var(&s.LargeClusterSizeThreshold, "large-cluster-size-threshold", 50, "Number of nodes from which NodeController treats the cluster as large for the eviction logic purposes. --secondary-node-eviction-rate is implicitly overridden to 0 for clusters this size or smaller.")
 	fs.Float32Var(&s.UnhealthyZoneThreshold, "unhealthy-zone-threshold", 0.55, "Fraction of Nodes in a zone which needs to be not Ready (minimum 3) for zone to be treated as unhealthy. ")
 	fs.BoolVar(&s.DisableAttachDetachReconcilerSync, "disable-attach-detach-reconcile-sync", false, "Disable volume attach detach reconciler sync. Disabling this may cause volumes to be mismatched with pods. Use wisely.")
+	fs.BoolVar(&s.KeepTerminatedPodVolumes, "keep-terminated-pod-volumes", false, "Keep terminated pod volumes attached to the node after the pod terminates.  Can be useful for debugging volume related issues.")


-> keep volumes attached to node ?

rootfs · 2017-05-03T19:14:05Z

pkg/apis/componentconfig/types.go

@@ -896,6 +896,10 @@ type KubeControllerManagerConfiguration struct {
 	// through the kube-aggregator when enabled, instead of using the legacy metrics client
 	// through the API server proxy.
 	HorizontalPodAutoscalerUseRESTClients bool
+
+	// KeepTerminatedPodVolumes causes terminated pod volumes attached to the node after the pod terminates.


=> KeepTerminatedPodVolumes keeps volumes attached to node after the pod terminates?

saad-ali · 2017-05-03T21:16:53Z

Largely looks fine to me. A couple of concerns:

This makes the detach routine even more aggressive. I'm wary of doing that unless it is absolutely necessary since bugs here can result in a disk being pulled from a volume in use (and potential data loss).
keep-terminated-pod-volumes is a flag on kubelet. You are adding it to the kube-controller-manager. How do they stay in sync? This is why flags are a poor way to configure k8s components, but I guess that's beyond the scope of this PR. At the very least please update the existing references to also set the new reference (e.g. hack/local-up-cluster.sh).

Will leave it to @jingxu97 for a more in depth review.

gnufied · 2017-05-03T21:29:06Z

For concern-1, I think this is needed because Completed, Failed or Terminated pods currently leave the volume attached to the node and currently kubectl get pods for example doesn't even show completed pods, as a result we have users thinking they can reuse the PVC in other pod. But obviously that doesn't work. We had many users struggling with this. cc @eparis

For concern-2, yeah it is bit iffy. I am hoping that most users would run with default and hence kubelet and controller flags will be in sync. But I am also thinking of improving documentation of the flag in controller and mention corresponding flag in kubelet, so as users know about both of them. ack about updating references in ./hack/**

jingxu97 · 2017-05-03T22:47:23Z

pkg/controller/volume/attachdetach/attach_detach_controller.go

+		addPodFlag = false
+	}
+
+	util.ProcessPodVolumes(pod, addPodFlag, /* addVolumes */


I am thinking to be consistent with kubelet, for podAdd function, we can also check whether the pod is already terminated or not. It might be necessary if podAdd means pod would never be in terminated state...

We do check that right? On line#415 (https://github.com/kubernetes/kubernetes/pull/45286/files#diff-72e66cba2ced392dc0f9cd10c424d6d0R415 )

I do not think there is any chance we are going to detach volumes still mounted and being used inside pod.

but that is for podUpdate, not podAdd?

eparis · 2017-05-03T23:31:30Z

We could make kubelet set "keep-terminated-pod-volumes" as a node annotation (similar to how we do master-attach-detach) then use that? I hate it, but we can if someone says we have to. I want no new flags if there is any way to do that. Not everything needs to be a choice.

I do question if setting keep-terminated-pod-volumes 'per-node' is/was really appropriate or if it should be a cluster wide things.

rootfs · 2017-05-04T14:18:10Z

also see #45346

sjenning · 2017-05-04T18:06:15Z

@eparis yeah, at the time I introduced that code and the new flag, it was geared toward freeing up emptydirs on pod termination. The detach-attach part of the PVs that might be associated with those mounts were outside the discussion at the time.

Like Saad, I do worry about keeping the flags in sync. If they are not, the attach-detach controller could end up force detaching mounted volumes and maybe causing corruption if the data previously written by the terminated pod is not synced before the forced detach.

However, if you can sync the data to volumes upon pod termination, I guess the worst that could happen is that your volumes are not their for debugging even if you set --keep-terminated-pod-volumes on the kubelet.

derekwaynecarr · 2017-05-11T17:15:37Z

/approve

childsb · 2017-05-11T17:17:58Z

/lgtm

gnufied · 2017-05-11T17:18:24Z

@k8s-bot bazel test this.

addressed

saad-ali · 2017-05-11T20:14:39Z

Taking a quick final pass

saad-ali

A few nits. Feel free to address them here and do a self-LGTM or in a follow up PR.

saad-ali · 2017-05-11T20:15:30Z

pkg/controller/volume/attachdetach/cache/desired_state_of_world.go

@@ -144,6 +148,9 @@ type nodeManaged struct {
 	// attached to this node. The key in the map is the name of the volume and
 	// the value is a pod object containing more information about the volume.
 	volumesToAttach map[v1.UniqueVolumeName]volumeToAttach
+
+	// keepTerminatedPodVolumes


nit: More descriptive comment please!

saad-ali · 2017-05-11T20:16:23Z

pkg/controller/volume/attachdetach/cache/desired_state_of_world.go

@@ -46,7 +46,7 @@ type DesiredStateOfWorld interface {
 	// AddNode adds the given node to the list of nodes managed by the attach/
 	// detach controller.
 	// If the node already exists this is a no-op.
-	AddNode(nodeName k8stypes.NodeName)
+	AddNode(nodeName k8stypes.NodeName, keepTerminatedPodVolumes bool)


nit: Update comment to describe the new parameter. This is particularly important for interfaces so that callers and implementers know what the expectations are.

saad-ali · 2017-05-11T20:23:52Z

/lgtm
/approve

gnufied · 2017-05-11T20:27:20Z

Given rather long build times right now because of bazel problems(kubernetes/test-infra#2708, #45558) - I am going to make the comment fixes as part of #45615.

I will make a note for myself. thanks @saad-ali

gnufied · 2017-05-12T01:54:58Z

@k8s-bot bazel test this

eparis · 2017-05-12T02:10:24Z

@k8s-bot unit test this

Make sure volume is detached when pod is terminated because of any reason and not deleted from api server.

gnufied · 2017-05-12T02:22:38Z

@eparis this needs a small code change now, which I am pushing. Basically master has changed contract of RunAMaster now - https://github.com/kubernetes/kubernetes/blob/master/test/integration/volume/attach_detach_test.go#L80

Obviously tests I added still uses old signature and it broke. Likely the change that changed the method signature was added after everything was green.

and lets make sure that controller respects it and doesn't detaches mounted volumes.

gnufied · 2017-05-12T02:34:46Z

I have pushed a fix for integration tests which were failing because change in RunAMaster signature. Also fixed comments by @saad-ali while at it.

gnufied · 2017-05-12T02:35:14Z

/lgtm

k8s-ci-robot · 2017-05-12T02:35:14Z

@gnufied: you cannot LGTM your own PR.

In response to this:

/lgtm

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k8s-github-robot · 2017-05-12T02:39:19Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: childsb, deads2k, derekwaynecarr, eparis, gnufied, jsafrane, saad-ali

Needs approval from an approver in each of these OWNERS Files:

~~cmd/kube-controller-manager/OWNERS~~ [deads2k]
~~hack/OWNERS~~ [deads2k,eparis]
~~pkg/controller/volume/attachdetach/OWNERS~~ [childsb,deads2k,derekwaynecarr,jsafrane,saad-ali]
~~pkg/kubelet/OWNERS~~ [derekwaynecarr]
~~pkg/volume/util/OWNERS~~ [childsb,gnufied,jsafrane,saad-ali]
~~test/OWNERS~~ [deads2k,eparis,saad-ali]

You can indicate your approval by writing /approve in a comment
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k8s-github-robot · 2017-05-12T04:46:28Z

Automatic merge from submit-queue

k8s-ci-robot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label May 3, 2017

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gnufied changed the title ~~[WIP] detach the volume when pod is terminated~~ detach the volume when pod is terminated May 3, 2017

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detach the volume when pod is terminated

9a1a9cb

Make sure volume is detached when pod is terminated because of any reason and not deleted from api server.

Add Keepterminatedpodvolumes as a annotation on node

951a36a

and lets make sure that controller respects it and doesn't detaches mounted volumes.

gnufied force-pushed the fix-terminated-pods-detach branch from 826582d to 951a36a Compare May 12, 2017 02:33

k8s-github-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label May 12, 2017

eparis added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label May 12, 2017

k8s-github-robot merged commit 3168760 into kubernetes:master May 12, 2017

This was referenced Sep 18, 2017

Boskos server fail to claim pv after restart/reschedule from the node kubernetes/test-infra#4571

Closed

Add e2e test for testing detach volume after pod is evicted. #52676

Closed

jingxu97 mentioned this pull request Sep 26, 2017

Unable to detach the vSphere volume from Powered off node #52575

Merged

		@@ -395,8 +401,23 @@ func (adc *attachDetachController) GetDesiredStateOfWorld() cache.DesiredStateOf
		}

		func (adc *attachDetachController) podUpdate(oldObj, newObj interface{}) {

detach the volume when pod is terminated #45286

detach the volume when pod is terminated #45286

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