Don't try to attach volumes which are already attached to other nodes

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

@@ -111,6 +111,9 @@ type ActualStateOfWorld interface {
 
 	GetAttachedVolumesPerNode() map[types.NodeName][]operationexecutor.AttachedVolume
 
+	// GetNodesForVolume returns the nodes on which the volume is attached
+	GetNodesForVolume(volumeName v1.UniqueVolumeName) []types.NodeName
+
 	// GetVolumesToReportAttached returns a map containing the set of nodes for
 	// which the VolumesAttached Status field in the Node API object should be
 	// updated. The key in this map is the name of the node to update and the
@@ -581,6 +584,22 @@ func (asw *actualStateOfWorld) GetAttachedVolumesPerNode() map[types.NodeName][]
 	return attachedVolumesPerNode
 }
 
+func (asw *actualStateOfWorld) GetNodesForVolume(volumeName v1.UniqueVolumeName) []types.NodeName {
+	asw.RLock()
+	defer asw.RUnlock()
+
+	volumeObj, volumeExists := asw.attachedVolumes[volumeName]
+	if !volumeExists || len(volumeObj.nodesAttachedTo) == 0 {
+		return []types.NodeName{}
+	}
+
+	nodes := []types.NodeName{}
+	for k := range volumeObj.nodesAttachedTo {
+		nodes = append(nodes, k)
+	}
+	return nodes
+}
+
 func (asw *actualStateOfWorld) GetVolumesToReportAttached() map[types.NodeName][]v1.AttachedVolume {
 	asw.RLock()
 	defer asw.RUnlock()

pkg/controller/volume/attachdetach/reconciler/BUILD

@@ -13,10 +13,11 @@ go_library(
     srcs = ["reconciler.go"],
     tags = ["automanaged"],
     deps = [
+        "//pkg/api/v1:go_default_library",
         "//pkg/controller/volume/attachdetach/cache:go_default_library",
         "//pkg/controller/volume/attachdetach/statusupdater:go_default_library",
         "//pkg/util/goroutinemap/exponentialbackoff:go_default_library",
-        "//pkg/volume/util/nestedpendingoperations:go_default_library",
+        "//pkg/volume:go_default_library",
         "//pkg/volume/util/operationexecutor:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",

pkg/controller/volume/attachdetach/reconciler/reconciler.go

@@ -25,10 +25,11 @@ import (
 
 	"github.com/golang/glog"
 	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/kubernetes/pkg/api/v1"
 	"k8s.io/kubernetes/pkg/controller/volume/attachdetach/cache"
 	"k8s.io/kubernetes/pkg/controller/volume/attachdetach/statusupdater"
 	"k8s.io/kubernetes/pkg/util/goroutinemap/exponentialbackoff"
-	"k8s.io/kubernetes/pkg/volume/util/nestedpendingoperations"
+	"k8s.io/kubernetes/pkg/volume"
 	"k8s.io/kubernetes/pkg/volume/util/operationexecutor"
 )
 
@@ -125,6 +126,41 @@ func (rc *reconciler) syncStates() {
 	rc.attacherDetacher.VerifyVolumesAreAttached(volumesPerNode, rc.actualStateOfWorld)
 }
 
+// isMultiAttachForbidden checks if attaching this volume to multiple nodes is definitely not allowed/possible.
+// In its current form, this function can only reliably say for which volumes it's definitely forbidden. If it returns
+// false, it is not guaranteed that multi-attach is actually supported by the volume type and we must rely on the
+// attacher to fail fast in such cases.
+// Please see https://github.com/kubernetes/kubernetes/issues/40669 and https://github.com/kubernetes/kubernetes/pull/40148#discussion_r98055047
+func (rc *reconciler) isMultiAttachForbidden(volumeSpec *volume.Spec) bool {
+	if volumeSpec.Volume != nil {
+		// Check for volume types which are known to fail slow or cause trouble when trying to multi-attach
+		if volumeSpec.Volume.AzureDisk != nil ||
+			volumeSpec.Volume.Cinder != nil {
+			return true
+		}
+	}
+
+	// Only if this volume is a persistent volume, we have reliable information on wether it's allowed or not to
+	// multi-attach. We trust in the individual volume implementations to not allow unsupported access modes
+	if volumeSpec.PersistentVolume != nil {
+		if len(volumeSpec.PersistentVolume.Spec.AccessModes) == 0 {
+			// No access mode specified so we don't know for sure. Let the attacher fail if needed
+			return false
+		}
+
+		// check if this volume is allowed to be attached to multiple PODs/nodes, if yes, return false
+		for _, accessMode := range volumeSpec.PersistentVolume.Spec.AccessModes {
+			if accessMode == v1.ReadWriteMany || accessMode == v1.ReadOnlyMany {
+				return false
+			}
+		}
+		return true
+	}
+
+	// we don't know if it's supported or not and let the attacher fail later in cases it's not supported
+	return false
+}
+
 func (rc *reconciler) reconcile() {
 	// Detaches are triggered before attaches so that volumes referenced by
 	// pods that are rescheduled to a different node are detached first.
@@ -133,6 +169,16 @@ func (rc *reconciler) reconcile() {
 	for _, attachedVolume := range rc.actualStateOfWorld.GetAttachedVolumes() {
 		if !rc.desiredStateOfWorld.VolumeExists(
 			attachedVolume.VolumeName, attachedVolume.NodeName) {
+
+			// Don't even try to start an operation if there is already one running
+			// This check must be done before we do any other checks, as otherwise the other checks
+			// may pass while at the same time the volume leaves the pending state, resulting in
+			// double detach attempts
+			if rc.attacherDetacher.IsOperationPending(attachedVolume.VolumeName, "") {
+				glog.V(10).Infof("Operation for volume %q is already running. Can't start detach for %q", attachedVolume.VolumeName, attachedVolume.NodeName)
+				continue
+			}
+
 			// Set the detach request time
 			elapsedTime, err := rc.actualStateOfWorld.SetDetachRequestTime(attachedVolume.VolumeName, attachedVolume.NodeName)
 			if err != nil {
@@ -177,10 +223,8 @@ func (rc *reconciler) reconcile() {
 					glog.Infof(attachedVolume.GenerateMsgDetailed("attacherDetacher.DetachVolume started", fmt.Sprintf("This volume is not safe to detach, but maxWaitForUnmountDuration %v expired, force detaching", rc.maxWaitForUnmountDuration)))
 				}
 			}
-			if err != nil &&
-				!nestedpendingoperations.IsAlreadyExists(err) &&
-				!exponentialbackoff.IsExponentialBackoff(err) {
-				// Ignore nestedpendingoperations.IsAlreadyExists && exponentialbackoff.IsExponentialBackoff errors, they are expected.
+			if err != nil && !exponentialbackoff.IsExponentialBackoff(err) {
+				// Ignore exponentialbackoff.IsExponentialBackoff errors, they are expected.
 				// Log all other errors.
 				glog.Errorf(attachedVolume.GenerateErrorDetailed("attacherDetacher.DetachVolume failed to start", err).Error())
 			}
@@ -195,16 +239,28 @@ func (rc *reconciler) reconcile() {
 			glog.V(5).Infof(volumeToAttach.GenerateMsgDetailed("Volume attached--touching", ""))
 			rc.actualStateOfWorld.ResetDetachRequestTime(volumeToAttach.VolumeName, volumeToAttach.NodeName)
 		} else {
+			// Don't even try to start an operation if there is already one running
+			if rc.attacherDetacher.IsOperationPending(volumeToAttach.VolumeName, "") {
+				glog.V(10).Infof("Operation for volume %q is already running. Can't start attach for %q", volumeToAttach.VolumeName, volumeToAttach.NodeName)
+				continue
+			}
+
+			if rc.isMultiAttachForbidden(volumeToAttach.VolumeSpec) {
+				nodes := rc.actualStateOfWorld.GetNodesForVolume(volumeToAttach.VolumeName)
+				if len(nodes) > 0 {
+					glog.V(4).Infof("Volume %q is already exclusively attached to node %q and can't be attached to %q", volumeToAttach.VolumeName, nodes, volumeToAttach.NodeName)
+					continue
+				}
+			}
+
 			// Volume/Node doesn't exist, spawn a goroutine to attach it
 			glog.V(5).Infof(volumeToAttach.GenerateMsgDetailed("Starting attacherDetacher.AttachVolume", ""))
 			err := rc.attacherDetacher.AttachVolume(volumeToAttach.VolumeToAttach, rc.actualStateOfWorld)
 			if err == nil {
 				glog.Infof(volumeToAttach.GenerateMsgDetailed("attacherDetacher.AttachVolume started", ""))
 			}
-			if err != nil &&
-				!nestedpendingoperations.IsAlreadyExists(err) &&
-				!exponentialbackoff.IsExponentialBackoff(err) {
-				// Ignore nestedpendingoperations.IsAlreadyExists && exponentialbackoff.IsExponentialBackoff errors, they are expected.
+			if err != nil && !exponentialbackoff.IsExponentialBackoff(err) {
+				// Ignore exponentialbackoff.IsExponentialBackoff errors, they are expected.
 				// Log all other errors.
 				glog.Errorf(volumeToAttach.GenerateErrorDetailed("attacherDetacher.AttachVolume failed to start", err).Error())
 			}