Retry assigning CIDRs

pkg/controller/node/cidr_allocator.go

@@ -20,10 +20,13 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"sync"
 
 	"k8s.io/kubernetes/pkg/api"
+	apierrors "k8s.io/kubernetes/pkg/api/errors"
 	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
 	"k8s.io/kubernetes/pkg/client/record"
+	"k8s.io/kubernetes/pkg/util/sets"
 	"k8s.io/kubernetes/pkg/util/wait"
 
 	"github.com/golang/glog"
@@ -60,6 +63,9 @@ type rangeAllocator struct {
 	// This increases a throughput of CIDR assignment by not blocking on long operations.
 	nodeCIDRUpdateChannel chan nodeAndCIDR
 	recorder              record.EventRecorder
+	// Keep a set of nodes that are currectly being processed to avoid races in CIDR allocation
+	sync.Mutex
+	nodesInProcessing sets.String
 }
 
 // NewCIDRRangeAllocator returns a CIDRAllocator to allocate CIDR for node
@@ -77,6 +83,7 @@ func NewCIDRRangeAllocator(client clientset.Interface, clusterCIDR *net.IPNet, s
 		clusterCIDR:           clusterCIDR,
 		nodeCIDRUpdateChannel: make(chan nodeAndCIDR, cidrUpdateQueueSize),
 		recorder:              recorder,
+		nodesInProcessing:     sets.NewString(),
 	}
 
 	if serviceCIDR != nil {
@@ -122,7 +129,24 @@ func NewCIDRRangeAllocator(client clientset.Interface, clusterCIDR *net.IPNet, s
 	return ra, nil
 }
 
+func (r *rangeAllocator) insertNodeToProcessing(nodeName string) bool {
+	r.Lock()
+	defer r.Unlock()
+	if r.nodesInProcessing.Has(nodeName) {
+		return false
+	}
+	r.nodesInProcessing.Insert(nodeName)
+	return true
+}
+
+func (r *rangeAllocator) removeNodeFromProcessing(nodeName string) {
+	r.Lock()
+	defer r.Unlock()
+	r.nodesInProcessing.Delete(nodeName)
+}
+
 func (r *rangeAllocator) occupyCIDR(node *api.Node) error {
+	defer r.removeNodeFromProcessing(node.Name)
 	if node.Spec.PodCIDR == "" {
 		return nil
 	}
@@ -138,12 +162,22 @@ func (r *rangeAllocator) occupyCIDR(node *api.Node) error {
 
 // AllocateOrOccupyCIDR looks at the given node, assigns it a valid CIDR
 // if it doesn't currently have one or mark the CIDR as used if the node already have one.
+// WARNING: If you're adding any return calls or defer any more work from this function
+// you have to handle correctly nodesInProcessing.
 func (r *rangeAllocator) AllocateOrOccupyCIDR(node *api.Node) error {
+	if node == nil {
+		return nil
+	}
+	if !r.insertNodeToProcessing(node.Name) {
+		glog.V(2).Infof("Node %v is already in a process of CIDR assignment.", node.Name)
+		return nil
+	}
 	if node.Spec.PodCIDR != "" {
 		return r.occupyCIDR(node)
 	}
 	podCIDR, err := r.cidrs.allocateNext()
 	if err != nil {
+		r.removeNodeFromProcessing(node.Name)
 		recordNodeStatusChange(r.recorder, node, "CIDRNotAvailable")
 		return fmt.Errorf("failed to allocate cidr: %v", err)
 	}
@@ -173,8 +207,8 @@ func (r *rangeAllocator) ReleaseCIDR(node *api.Node) error {
 	return err
 }
 
-// Marks all CIDRs with subNetMaskSize that belongs to serviceCIDR as used, so that they won't be
-// assignable.
+// Marks all CIDRs with subNetMaskSize that belongs to serviceCIDR as used,
+// so that they won't be assignable.
 func (r *rangeAllocator) filterOutServiceRange(serviceCIDR *net.IPNet) {
 	// Checks if service CIDR has a nonempty intersection with cluster CIDR. It is the case if either
 	// clusterCIDR contains serviceCIDR with clusterCIDR's Mask applied (this means that clusterCIDR contains serviceCIDR)
@@ -192,6 +226,7 @@ func (r *rangeAllocator) filterOutServiceRange(serviceCIDR *net.IPNet) {
 func (r *rangeAllocator) updateCIDRAllocation(data nodeAndCIDR) error {
 	var err error
 	var node *api.Node
+	defer r.removeNodeFromProcessing(data.nodeName)
 	for rep := 0; rep < podCIDRUpdateRetry; rep++ {
 		// TODO: change it to using PATCH instead of full Node updates.
 		node, err = r.client.Core().Nodes().Get(data.nodeName)
@@ -217,9 +252,14 @@ func (r *rangeAllocator) updateCIDRAllocation(data nodeAndCIDR) error {
 	}
 	if err != nil {
 		recordNodeStatusChange(r.recorder, node, "CIDRAssignmentFailed")
-		glog.Errorf("CIDR assignment for node %v failed: %v. Releasing allocated CIDR", data.nodeName, err)
-		if releaseErr := r.cidrs.release(data.cidr); releaseErr != nil {
-			glog.Errorf("Error releasing allocated CIDR for node %v: %v", data.nodeName, releaseErr)
+		// We accept the fact that we may leek CIDRs here. This is safer than releasing
+		// them in case when we don't know if request went through.
+		// NodeController restart will return all falsely allocated CIDRs to the pool.
+		if !apierrors.IsServerTimeout(err) {
+			glog.Errorf("CIDR assignment for node %v failed: %v. Releasing allocated CIDR", data.nodeName, err)
+			if releaseErr := r.cidrs.release(data.cidr); releaseErr != nil {
+				glog.Errorf("Error releasing allocated CIDR for node %v: %v", data.nodeName, releaseErr)
+			}
 		}
 	}
 	return err

pkg/controller/node/cidr_set.go

@@ -78,26 +78,13 @@ func (s *cidrSet) allocateNext() (*net.IPNet, error) {
 	}, nil
 }
 
-func (s *cidrSet) release(cidr *net.IPNet) error {
-	used, err := s.getIndexForCIDR(cidr)
-	if err != nil {
-		return err
-	}
-
-	s.Lock()
-	defer s.Unlock()
-	s.used.SetBit(&s.used, used, 0)
-
-	return nil
-}
-
-func (s *cidrSet) occupy(cidr *net.IPNet) (err error) {
-	begin, end := 0, s.maxCIDRs
+func (s *cidrSet) getBeginingAndEndIndices(cidr *net.IPNet) (begin, end int, err error) {
+	begin, end = 0, s.maxCIDRs
 	cidrMask := cidr.Mask
 	maskSize, _ := cidrMask.Size()
 
 	if !s.clusterCIDR.Contains(cidr.IP.Mask(s.clusterCIDR.Mask)) && !cidr.Contains(s.clusterCIDR.IP.Mask(cidr.Mask)) {
-		return fmt.Errorf("cidr %v is out the range of cluster cidr %v", cidr, s.clusterCIDR)
+		return -1, -1, fmt.Errorf("cidr %v is out the range of cluster cidr %v", cidr, s.clusterCIDR)
 	}
 
 	if s.clusterMaskSize < maskSize {
@@ -107,7 +94,7 @@ func (s *cidrSet) occupy(cidr *net.IPNet) (err error) {
 			Mask: subNetMask,
 		})
 		if err != nil {
-			return err
+			return -1, -1, err
 		}
 
 		ip := make([]byte, 4)
@@ -118,9 +105,30 @@ func (s *cidrSet) occupy(cidr *net.IPNet) (err error) {
 			Mask: subNetMask,
 		})
 		if err != nil {
-			return err
+			return -1, -1, err
 		}
 	}
+	return begin, end, nil
+}
+
+func (s *cidrSet) release(cidr *net.IPNet) error {
+	begin, end, err := s.getBeginingAndEndIndices(cidr)
+	if err != nil {
+		return err
+	}
+	s.Lock()
+	defer s.Unlock()
+	for i := begin; i <= end; i++ {
+		s.used.SetBit(&s.used, i, 0)
+	}
+	return nil
+}
+
+func (s *cidrSet) occupy(cidr *net.IPNet) (err error) {
+	begin, end, err := s.getBeginingAndEndIndices(cidr)
+	if err != nil {
+		return err
+	}
 
 	s.Lock()
 	defer s.Unlock()

pkg/controller/node/nodecontroller.go

@@ -244,6 +244,34 @@ func NewNodeController(
 					glog.Errorf("Error allocating CIDR: %v", err)
 				}
 			},
+			UpdateFunc: func(_, obj interface{}) {
+				node := obj.(*api.Node)
+				// If the PodCIDR is not empty we either:
+				// - already processed a Node that already had a CIDR after NC restarted
+				//   (cidr is marked as used),
+				// - already processed a Node successfully and allocated a CIDR for it
+				//   (cidr is marked as used),
+				// - already processed a Node but we did saw a "timeout" response and
+				//   request eventually got through in this case we haven't released
+				//   the allocated CIDR (cidr is still marked as used).
+				// There's a possible error here:
+				// - NC sees a new Node and assigns a CIDR X to it,
+				// - Update Node call fails with a timeout,
+				// - Node is updated by some other component, NC sees an update and
+				//   assigns CIDR Y to the Node,
+				// - Both CIDR X and CIDR Y are marked as used in the local cache,
+				//   even though Node sees only CIDR Y
+				// The problem here is that in in-memory cache we see CIDR X as marked,
+				// which prevents it from being assigned to any new node. The cluster
+				// state is correct.
+				// Restart of NC fixes the issue.
+				if node.Spec.PodCIDR == "" {
+					err := nc.cidrAllocator.AllocateOrOccupyCIDR(node)
+					if err != nil {
+						glog.Errorf("Error allocating CIDR: %v", err)
+					}
+				}
+			},
 			DeleteFunc: func(obj interface{}) {
 				node := obj.(*api.Node)
 				err := nc.cidrAllocator.ReleaseCIDR(node)