Change:
} } <ins> func TestAssignsDefaultServiceAccountAndBoundTokenWithNoSecretTokens(t *testing.T) { ns := "myns" admit := NewServiceAccount() informerFactory := informers.NewSharedInformerFactory(nil, controller.NoResyncPeriodFunc()) admit.SetExternalKubeInformerFactory(informerFactory) admit.MountServiceAccountToken = true admit.RequireAPIToken = true admit.boundServiceAccountTokenVolume = true // Add the default service account for the ns into the cache informerFactory.Core().V1().ServiceAccounts().Informer().GetStore().Add(&corev1.ServiceAccount{ ObjectMeta: metav1.ObjectMeta{ Name:      DefaultServiceAccountName, Namespace: ns, }, }) pod := &api.Pod{ Spec: api.PodSpec{ Containers: []api.Container{{}}, }, } attrs := admission.NewAttributesRecord(pod, nil, api.Kind("Pod").WithVersion("version"), ns, "myname", api.Resource("pods").WithVersion("version"), "", admission.Create, &metav1.CreateOptions{}, false, nil) err := admissiontesting.WithReinvocationTesting(t, admit).Admit(context.TODO(), attrs, nil) if err != nil { t.Fatalf("Expected success, got: %v", err) } expectedVolumes := []api.Volume{{ Name: "cleared", VolumeSource: api.VolumeSource{ Projected: &api.ProjectedVolumeSource{ Sources: []api.VolumeProjection{ {ServiceAccountToken: &api.ServiceAccountTokenProjection{ExpirationSeconds: 3600, Path: "token"}}, {ConfigMap: &api.ConfigMapProjection{LocalObjectReference: api.LocalObjectReference{Name: "kube-root-ca.crt"}, Items: []api.KeyToPath{{Key: "ca.crt", Path: "ca.crt"}}}}, {DownwardAPI: &api.DownwardAPIProjection{Items: []api.DownwardAPIVolumeFile{{Path: "namespace", FieldRef: &api.ObjectFieldSelector{APIVersion: "v1", FieldPath: "metadata.namespace"}}}}}, }, }, }, }} expectedVolumeMounts := []api.VolumeMount{{ Name:      "cleared", ReadOnly:  true, MountPath: "/var/run/secrets/kubernetes.io/serviceaccount", }} // clear generated volume names for i := range pod.Spec.Volumes { if len(pod.Spec.Volumes[i].Name) > 0 { pod.Spec.Volumes[i].Name = "cleared" } } for i := range pod.Spec.Containers[0].VolumeMounts { if len(pod.Spec.Containers[0].VolumeMounts[i].Name) > 0 { pod.Spec.Containers[0].VolumeMounts[i].Name = "cleared" } } if !reflect.DeepEqual(expectedVolumes, pod.Spec.Volumes) { t.Errorf("unexpected volumes: %s", diff.ObjectReflectDiff(expectedVolumes, pod.Spec.Volumes)) } if !reflect.DeepEqual(expectedVolumeMounts, pod.Spec.Containers[0].VolumeMounts) { t.Errorf("unexpected volumes: %s", diff.ObjectReflectDiff(expectedVolumeMounts, pod.Spec.Containers[0].VolumeMounts)) } } </ins> func TestFetchesUncachedServiceAccount(t *testing.T) { ns := "myns"

Discussion:
What happened: We enabled the feature gate on to start switching from non-expiring to expiring ServiceAccount tokens as . It works well. We then wanted to completely get rid of the "legacy" non-expiring ServiceAccount token Secrets. To do that we configured with (so it wouldn't auto-create the Secrets), removed the existing Secrets and removed the reference from the respective ServiceAccount to the Secret. This works as expected: No non-expiring token Secrets are generated. However, when creating a Pod we now see: This happens because the rejects the Pod because it cannot find a ServiceAccount token Secret (because it doesn't exist anymore as intended). What you expected to happen: When using the feature the legacy ServiceAccount token Secrets aren't used anymore, so a Pod should not be rejected if the Secret doesn't exist. The Pod doesn't even use the Secret at all. How to reproduce it (as minimally and precisely as possible): Enable feature gate Start with Create a new ServiceAccount Deploy a dummy app using that ServiceAccount Observe no Pod being created with Describe the corresponding ReplicaSet to see the above Error event. Anything else we need to know?: Looking at the it seems that at least one legacy Secret must exist in order for the Pod to get admitted. This is enforced even when and we're relying on projected token volumes. Following the code path when is enabled reveals that the token is never going to be used later on as there's no SecretVolume to be mounted in . In other words:  is just fine when . During the transition period it's fine to have the legacy Secrets lying around but ultimately it's desirable to get rid of them because as far as I can tell they are still happily accepted by the API server. Environment: Kubernetes version: tested on but code seems the same in and Cloud provider or hardware configuration: OS (e.g: ): Ubuntu 18.04.3 LTS Kernel (e.g. ): 4.15.0-1054-aws Install tools: /kind bug /sig auth
Fixed in
Thank you!