dra resourceclaim controller: remove reservation for completed pods

When a pod is known to never run (again), the reservation for it also can be
removed. This is relevant in particular for the job controller.

pkg/controller/resourceclaim/controller.go

@@ -435,10 +435,10 @@ func (ec *Controller) syncClaim(ctx context.Context, namespace, name string) err
 				keepEntry = false
 			} else {
 				pod, err := ec.podLister.Pods(claim.Namespace).Get(reservedFor.Name)
-				if err != nil && !errors.IsNotFound(err) {
+				switch {
+				case err != nil && !errors.IsNotFound(err):
 					return err
-				}
-				if pod == nil {
+				case err != nil:
 					// We might not have it in our informer cache
 					// yet. Removing the pod while the scheduler is
 					// scheduling it would be bad. We have to be
@@ -449,10 +449,14 @@ func (ec *Controller) syncClaim(ctx context.Context, namespace, name string) err
 						return err
 					}
 					if pod == nil || pod.UID != reservedFor.UID {
+						logger.V(6).Info("remove reservation because pod is gone or got replaced", "pod", klog.KObj(pod), "claim", klog.KRef(namespace, name))
 						keepEntry = false
 					}
-				} else if pod.UID != reservedFor.UID {
-					// Pod exists, but is a different incarnation under the same name.
+				case pod.UID != reservedFor.UID:
+					logger.V(6).Info("remove reservation because pod got replaced with new instance", "pod", klog.KObj(pod), "claim", klog.KRef(namespace, name))
+					keepEntry = false
+				case isPodDone(pod):
+					logger.V(6).Info("remove reservation because pod will not run anymore", "pod", klog.KObj(pod), "claim", klog.KRef(namespace, name))
 					keepEntry = false
 				}
 			}

pkg/controller/resourceclaim/controller_test.go

@@ -187,6 +187,27 @@ func TestSyncHandler(t *testing.T) {
 			expectedClaims:  []resourcev1alpha2.ResourceClaim{*testClaim},
 			expectedMetrics: expectedMetrics{0, 0},
 		},
+		{
+			name: "clear-reserved-when-done",
+			pods: func() []*v1.Pod {
+				pods := []*v1.Pod{testPodWithResource.DeepCopy()}
+				pods[0].Status.Phase = v1.PodSucceeded
+				return pods
+			}(),
+			key: claimKey(testClaimReserved),
+			claims: func() []*resourcev1alpha2.ResourceClaim {
+				claims := []*resourcev1alpha2.ResourceClaim{testClaimReserved.DeepCopy()}
+				claims[0].OwnerReferences = nil
+				return claims
+			}(),
+			expectedClaims: func() []resourcev1alpha2.ResourceClaim {
+				claims := []resourcev1alpha2.ResourceClaim{*testClaimReserved.DeepCopy()}
+				claims[0].OwnerReferences = nil
+				claims[0].Status.ReservedFor = nil
+				return claims
+			}(),
+			expectedMetrics: expectedMetrics{0, 0},
+		},
 		{
 			name:            "remove-reserved",
 			pods:            []*v1.Pod{testPod},

test/e2e/dra/dra.go

@@ -230,6 +230,21 @@ var _ = ginkgo.Describe("[sig-node] DRA [Feature:DynamicResourceAllocation]", fu
 
 				b.testPod(ctx, f.ClientSet, pod)
 			})
+
+			ginkgo.It("removes reservation from claim when pod is done", func(ctx context.Context) {
+				parameters := b.parameters()
+				pod := b.podExternal()
+				claim := b.externalClaim(allocationMode)
+				pod.Spec.Containers[0].Command = []string{"true"}
+				b.create(ctx, parameters, claim, pod)
+
+				ginkgo.By("waiting for pod to finish")
+				framework.ExpectNoError(e2epod.WaitForPodNoLongerRunningInNamespace(ctx, f.ClientSet, pod.Name, pod.Namespace), "wait for pod to finish")
+				ginkgo.By("waiting for claim to be unreserved")
+				gomega.Eventually(ctx, func(ctx context.Context) (*resourcev1alpha2.ResourceClaim, error) {
+					return f.ClientSet.ResourceV1alpha2().ResourceClaims(pod.Namespace).Get(ctx, claim.Name, metav1.GetOptions{})
+				}).WithTimeout(f.Timeouts.PodDelete).Should(gomega.HaveField("Status.ReservedFor", gomega.BeEmpty()), "reservation should have been removed")
+			})
 		}
 
 		ginkgo.Context("with delayed allocation", func() {