wait.go

/*
Copyright 2019 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package pod

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"sync"
	"text/tabwriter"
	"time"

	"github.com/onsi/ginkgo"

	v1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/util/wait"
	clientset "k8s.io/client-go/kubernetes"
	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
	"k8s.io/kubernetes/pkg/kubelet/util/format"
	e2elog "k8s.io/kubernetes/test/e2e/framework/log"
	e2eresource "k8s.io/kubernetes/test/e2e/framework/resource"
	testutils "k8s.io/kubernetes/test/utils"
)

const (
	// defaultPodDeletionTimeout is the default timeout for deleting pod.
	defaultPodDeletionTimeout = 3 * time.Minute

	// podListTimeout is how long to wait for the pod to be listable.
	podListTimeout = time.Minute

	podRespondingTimeout = 15 * time.Minute

	// How long pods have to become scheduled onto nodes
	podScheduledBeforeTimeout = podListTimeout + (20 * time.Second)

	// podStartTimeout is how long to wait for the pod to be started.
	podStartTimeout = 5 * time.Minute

	// poll is how often to poll pods, nodes and claims.
	poll = 2 * time.Second

	// singleCallTimeout is how long to try single API calls (like 'get' or 'list'). Used to prevent
	// transient failures from failing tests.
	singleCallTimeout = 5 * time.Minute

	// Some pods can take much longer to get ready due to volume attach/detach latency.
	slowPodStartTimeout = 15 * time.Minute
)

type podCondition func(pod *v1.Pod) (bool, error)

// errorBadPodsStates create error message of basic info of bad pods for debugging.
func errorBadPodsStates(badPods []v1.Pod, desiredPods int, ns, desiredState string, timeout time.Duration) string {
	errStr := fmt.Sprintf("%d / %d pods in namespace %q are NOT in %s state in %v\n", len(badPods), desiredPods, ns, desiredState, timeout)
	// Print bad pods info only if there are fewer than 10 bad pods
	if len(badPods) > 10 {
		return errStr + "There are too many bad pods. Please check log for details."
	}

	buf := bytes.NewBuffer(nil)
	w := tabwriter.NewWriter(buf, 0, 0, 1, ' ', 0)
	fmt.Fprintln(w, "POD\tNODE\tPHASE\tGRACE\tCONDITIONS")
	for _, badPod := range badPods {
		grace := ""
		if badPod.DeletionGracePeriodSeconds != nil {
			grace = fmt.Sprintf("%ds", *badPod.DeletionGracePeriodSeconds)
		}
		podInfo := fmt.Sprintf("%s\t%s\t%s\t%s\t%+v",
			badPod.ObjectMeta.Name, badPod.Spec.NodeName, badPod.Status.Phase, grace, badPod.Status.Conditions)
		fmt.Fprintln(w, podInfo)
	}
	w.Flush()
	return errStr + buf.String()
}

// WaitForPodsRunningReady waits up to timeout to ensure that all pods in
// namespace ns are either running and ready, or failed but controlled by a
// controller. Also, it ensures that at least minPods are running and
// ready. It has separate behavior from other 'wait for' pods functions in
// that it requests the list of pods on every iteration. This is useful, for
// example, in cluster startup, because the number of pods increases while
// waiting. All pods that are in SUCCESS state are not counted.
//
// If ignoreLabels is not empty, pods matching this selector are ignored.
func WaitForPodsRunningReady(c clientset.Interface, ns string, minPods, allowedNotReadyPods int32, timeout time.Duration, ignoreLabels map[string]string) error {
	ignoreSelector := labels.SelectorFromSet(map[string]string{})
	start := time.Now()
	e2elog.Logf("Waiting up to %v for all pods (need at least %d) in namespace '%s' to be running and ready",
		timeout, minPods, ns)
	wg := sync.WaitGroup{}
	wg.Add(1)
	var ignoreNotReady bool
	badPods := []v1.Pod{}
	desiredPods := 0
	notReady := int32(0)

	if wait.PollImmediate(poll, timeout, func() (bool, error) {
		// We get the new list of pods, replication controllers, and
		// replica sets in every iteration because more pods come
		// online during startup and we want to ensure they are also
		// checked.
		replicas, replicaOk := int32(0), int32(0)

		rcList, err := c.CoreV1().ReplicationControllers(ns).List(context.TODO(), metav1.ListOptions{})
		if err != nil {
			e2elog.Logf("Error getting replication controllers in namespace '%s': %v", ns, err)
			if testutils.IsRetryableAPIError(err) {
				return false, nil
			}
			return false, err
		}
		for _, rc := range rcList.Items {
			replicas += *rc.Spec.Replicas
			replicaOk += rc.Status.ReadyReplicas
		}

		rsList, err := c.AppsV1().ReplicaSets(ns).List(context.TODO(), metav1.ListOptions{})
		if err != nil {
			e2elog.Logf("Error getting replication sets in namespace %q: %v", ns, err)
			if testutils.IsRetryableAPIError(err) {
				return false, nil
			}
			return false, err
		}
		for _, rs := range rsList.Items {
			replicas += *rs.Spec.Replicas
			replicaOk += rs.Status.ReadyReplicas
		}

		podList, err := c.CoreV1().Pods(ns).List(context.TODO(), metav1.ListOptions{})
		if err != nil {
			e2elog.Logf("Error getting pods in namespace '%s': %v", ns, err)
			if testutils.IsRetryableAPIError(err) {
				return false, nil
			}
			return false, err
		}
		nOk := int32(0)
		notReady = int32(0)
		badPods = []v1.Pod{}
		desiredPods = len(podList.Items)
		for _, pod := range podList.Items {
			if len(ignoreLabels) != 0 && ignoreSelector.Matches(labels.Set(pod.Labels)) {
				continue
			}
			res, err := testutils.PodRunningReady(&pod)
			switch {
			case res && err == nil:
				nOk++
			case pod.Status.Phase == v1.PodSucceeded:
				e2elog.Logf("The status of Pod %s is Succeeded, skipping waiting", pod.ObjectMeta.Name)
				// it doesn't make sense to wait for this pod
				continue
			case pod.Status.Phase != v1.PodFailed:
				e2elog.Logf("The status of Pod %s is %s (Ready = false), waiting for it to be either Running (with Ready = true) or Failed", pod.ObjectMeta.Name, pod.Status.Phase)
				notReady++
				badPods = append(badPods, pod)
			default:
				if metav1.GetControllerOf(&pod) == nil {
					e2elog.Logf("Pod %s is Failed, but it's not controlled by a controller", pod.ObjectMeta.Name)
					badPods = append(badPods, pod)
				}
				//ignore failed pods that are controlled by some controller
			}
		}

		e2elog.Logf("%d / %d pods in namespace '%s' are running and ready (%d seconds elapsed)",
			nOk, len(podList.Items), ns, int(time.Since(start).Seconds()))
		e2elog.Logf("expected %d pod replicas in namespace '%s', %d are Running and Ready.", replicas, ns, replicaOk)

		if replicaOk == replicas && nOk >= minPods && len(badPods) == 0 {
			return true, nil
		}
		ignoreNotReady = (notReady <= allowedNotReadyPods)
		LogPodStates(badPods)
		return false, nil
	}) != nil {
		if !ignoreNotReady {
			return errors.New(errorBadPodsStates(badPods, desiredPods, ns, "RUNNING and READY", timeout))
		}
		e2elog.Logf("Number of not-ready pods (%d) is below the allowed threshold (%d).", notReady, allowedNotReadyPods)
	}
	return nil
}

// WaitForPodCondition waits a pods to be matched to the given condition.
func WaitForPodCondition(c clientset.Interface, ns, podName, desc string, timeout time.Duration, condition podCondition) error {
	e2elog.Logf("Waiting up to %v for pod %q in namespace %q to be %q", timeout, podName, ns, desc)
	for start := time.Now(); time.Since(start) < timeout; time.Sleep(poll) {
		pod, err := c.CoreV1().Pods(ns).Get(context.TODO(), podName, metav1.GetOptions{})
		if err != nil {
			if apierrors.IsNotFound(err) {
				e2elog.Logf("Pod %q in namespace %q not found. Error: %v", podName, ns, err)
				return err
			}
			e2elog.Logf("Get pod %q in namespace %q failed, ignoring for %v. Error: %v", podName, ns, poll, err)
			continue
		}
		// log now so that current pod info is reported before calling `condition()`
		e2elog.Logf("Pod %q: Phase=%q, Reason=%q, readiness=%t. Elapsed: %v",
			podName, pod.Status.Phase, pod.Status.Reason, podutil.IsPodReady(pod), time.Since(start))
		if done, err := condition(pod); done {
			if err == nil {
				e2elog.Logf("Pod %q satisfied condition %q", podName, desc)
			}
			return err
		}
	}
	return fmt.Errorf("Gave up after waiting %v for pod %q to be %q", timeout, podName, desc)
}

// WaitForPodTerminatedInNamespace returns an error if it takes too long for the pod to terminate,
// if the pod Get api returns an error (IsNotFound or other), or if the pod failed (and thus did not
// terminate) with an unexpected reason. Typically called to test that the passed-in pod is fully
// terminated (reason==""), but may be called to detect if a pod did *not* terminate according to
// the supplied reason.
func WaitForPodTerminatedInNamespace(c clientset.Interface, podName, reason, namespace string) error {
	return WaitForPodCondition(c, namespace, podName, "terminated due to deadline exceeded", podStartTimeout, func(pod *v1.Pod) (bool, error) {
		// Only consider Failed pods. Successful pods will be deleted and detected in
		// waitForPodCondition's Get call returning `IsNotFound`
		if pod.Status.Phase == v1.PodFailed {
			if pod.Status.Reason == reason { // short-circuit waitForPodCondition's loop
				return true, nil
			}
			return true, fmt.Errorf("Expected pod %q in namespace %q to be terminated with reason %q, got reason: %q", podName, namespace, reason, pod.Status.Reason)
		}
		return false, nil
	})
}

// waitForPodSuccessInNamespaceTimeout returns nil if the pod reached state success, or an error if it reached failure or ran too long.
func waitForPodSuccessInNamespaceTimeout(c clientset.Interface, podName, namespace string, timeout time.Duration) error {
	return WaitForPodCondition(c, namespace, podName, fmt.Sprintf("%s or %s", v1.PodSucceeded, v1.PodFailed), timeout, func(pod *v1.Pod) (bool, error) {
		if pod.Spec.RestartPolicy == v1.RestartPolicyAlways {
			return true, fmt.Errorf("pod %q will never terminate with a succeeded state since its restart policy is Always", podName)
		}
		switch pod.Status.Phase {
		case v1.PodSucceeded:
			ginkgo.By("Saw pod success")
			return true, nil
		case v1.PodFailed:
			return true, fmt.Errorf("pod %q failed with status: %+v", podName, pod.Status)
		default:
			return false, nil
		}
	})
}

// WaitForPodNameUnschedulableInNamespace returns an error if it takes too long for the pod to become Pending
// and have condition Status equal to Unschedulable,
// if the pod Get api returns an error (IsNotFound or other), or if the pod failed with an unexpected reason.
// Typically called to test that the passed-in pod is Pending and Unschedulable.
func WaitForPodNameUnschedulableInNamespace(c clientset.Interface, podName, namespace string) error {
	return WaitForPodCondition(c, namespace, podName, v1.PodReasonUnschedulable, podStartTimeout, func(pod *v1.Pod) (bool, error) {
		// Only consider Failed pods. Successful pods will be deleted and detected in
		// waitForPodCondition's Get call returning `IsNotFound`
		if pod.Status.Phase == v1.PodPending {
			for _, cond := range pod.Status.Conditions {
				if cond.Type == v1.PodScheduled && cond.Status == v1.ConditionFalse && cond.Reason == v1.PodReasonUnschedulable {
					return true, nil
				}
			}
		}
		if pod.Status.Phase == v1.PodRunning || pod.Status.Phase == v1.PodSucceeded || pod.Status.Phase == v1.PodFailed {
			return true, fmt.Errorf("Expected pod %q in namespace %q to be in phase Pending, but got phase: %v", podName, namespace, pod.Status.Phase)
		}
		return false, nil
	})
}

// WaitForMatchPodsCondition finds match pods based on the input ListOptions.
// waits and checks if all match pods are in the given podCondition
func WaitForMatchPodsCondition(c clientset.Interface, opts metav1.ListOptions, desc string, timeout time.Duration, condition podCondition) error {
	e2elog.Logf("Waiting up to %v for matching pods' status to be %s", timeout, desc)
	for start := time.Now(); time.Since(start) < timeout; time.Sleep(poll) {
		pods, err := c.CoreV1().Pods(metav1.NamespaceAll).List(context.TODO(), opts)
		if err != nil {
			return err
		}
		conditionNotMatch := []string{}
		for _, pod := range pods.Items {
			done, err := condition(&pod)
			if done && err != nil {
				return fmt.Errorf("Unexpected error: %v", err)
			}
			if !done {
				conditionNotMatch = append(conditionNotMatch, format.Pod(&pod))
			}
		}
		if len(conditionNotMatch) <= 0 {
			return err
		}
		e2elog.Logf("%d pods are not %s: %v", len(conditionNotMatch), desc, conditionNotMatch)
	}
	return fmt.Errorf("gave up waiting for matching pods to be '%s' after %v", desc, timeout)
}

// WaitForPodNameRunningInNamespace waits default amount of time (PodStartTimeout) for the specified pod to become running.
// Returns an error if timeout occurs first, or pod goes in to failed state.
func WaitForPodNameRunningInNamespace(c clientset.Interface, podName, namespace string) error {
	return WaitTimeoutForPodRunningInNamespace(c, podName, namespace, podStartTimeout)
}

// WaitForPodRunningInNamespaceSlow waits an extended amount of time (slowPodStartTimeout) for the specified pod to become running.
// The resourceVersion is used when Watching object changes, it tells since when we care
// about changes to the pod. Returns an error if timeout occurs first, or pod goes in to failed state.
func WaitForPodRunningInNamespaceSlow(c clientset.Interface, podName, namespace string) error {
	return WaitTimeoutForPodRunningInNamespace(c, podName, namespace, slowPodStartTimeout)
}

// WaitTimeoutForPodRunningInNamespace waits the given timeout duration for the specified pod to become running.
func WaitTimeoutForPodRunningInNamespace(c clientset.Interface, podName, namespace string, timeout time.Duration) error {
	return wait.PollImmediate(poll, timeout, podRunning(c, podName, namespace))
}

// WaitForPodRunningInNamespace waits default amount of time (podStartTimeout) for the specified pod to become running.
// Returns an error if timeout occurs first, or pod goes in to failed state.
func WaitForPodRunningInNamespace(c clientset.Interface, pod *v1.Pod) error {
	if pod.Status.Phase == v1.PodRunning {
		return nil
	}
	return WaitTimeoutForPodRunningInNamespace(c, pod.Name, pod.Namespace, podStartTimeout)
}

// WaitTimeoutForPodNoLongerRunningInNamespace waits the given timeout duration for the specified pod to stop.
func WaitTimeoutForPodNoLongerRunningInNamespace(c clientset.Interface, podName, namespace string, timeout time.Duration) error {
	return wait.PollImmediate(poll, timeout, podCompleted(c, podName, namespace))
}

// WaitForPodNoLongerRunningInNamespace waits default amount of time (defaultPodDeletionTimeout) for the specified pod to stop running.
// Returns an error if timeout occurs first.
func WaitForPodNoLongerRunningInNamespace(c clientset.Interface, podName, namespace string) error {
	return WaitTimeoutForPodNoLongerRunningInNamespace(c, podName, namespace, defaultPodDeletionTimeout)
}

// WaitTimeoutForPodReadyInNamespace waits the given timeout diration for the
// specified pod to be ready and running.
func WaitTimeoutForPodReadyInNamespace(c clientset.Interface, podName, namespace string, timeout time.Duration) error {
	return wait.PollImmediate(poll, timeout, podRunningAndReady(c, podName, namespace))
}

// WaitForPodNotPending returns an error if it took too long for the pod to go out of pending state.
// The resourceVersion is used when Watching object changes, it tells since when we care
// about changes to the pod.
func WaitForPodNotPending(c clientset.Interface, ns, podName string) error {
	return wait.PollImmediate(poll, podStartTimeout, podNotPending(c, podName, ns))
}

// WaitForPodSuccessInNamespace returns nil if the pod reached state success, or an error if it reached failure or until podStartupTimeout.
func WaitForPodSuccessInNamespace(c clientset.Interface, podName string, namespace string) error {
	return waitForPodSuccessInNamespaceTimeout(c, podName, namespace, podStartTimeout)
}

// WaitForPodSuccessInNamespaceSlow returns nil if the pod reached state success, or an error if it reached failure or until slowPodStartupTimeout.
func WaitForPodSuccessInNamespaceSlow(c clientset.Interface, podName string, namespace string) error {
	return waitForPodSuccessInNamespaceTimeout(c, podName, namespace, slowPodStartTimeout)
}

// WaitForPodNotFoundInNamespace returns an error if it takes too long for the pod to fully terminate.
// Unlike `waitForPodTerminatedInNamespace`, the pod's Phase and Reason are ignored. If the pod Get
// api returns IsNotFound then the wait stops and nil is returned. If the Get api returns an error other
// than "not found" then that error is returned and the wait stops.
func WaitForPodNotFoundInNamespace(c clientset.Interface, podName, ns string, timeout time.Duration) error {
	return wait.PollImmediate(poll, timeout, func() (bool, error) {
		_, err := c.CoreV1().Pods(ns).Get(context.TODO(), podName, metav1.GetOptions{})
		if apierrors.IsNotFound(err) {
			return true, nil // done
		}
		if err != nil {
			return true, err // stop wait with error
		}
		return false, nil
	})
}

// WaitForPodToDisappear waits the given timeout duration for the specified pod to disappear.
func WaitForPodToDisappear(c clientset.Interface, ns, podName string, label labels.Selector, interval, timeout time.Duration) error {
	return wait.PollImmediate(interval, timeout, func() (bool, error) {
		e2elog.Logf("Waiting for pod %s to disappear", podName)
		options := metav1.ListOptions{LabelSelector: label.String()}
		pods, err := c.CoreV1().Pods(ns).List(context.TODO(), options)
		if err != nil {
			if testutils.IsRetryableAPIError(err) {
				return false, nil
			}
			return false, err
		}
		found := false
		for _, pod := range pods.Items {
			if pod.Name == podName {
				e2elog.Logf("Pod %s still exists", podName)
				found = true
				break
			}
		}
		if !found {
			e2elog.Logf("Pod %s no longer exists", podName)
			return true, nil
		}
		return false, nil
	})
}

// PodsResponding waits for the pods to response.
func PodsResponding(c clientset.Interface, ns, name string, wantName bool, pods *v1.PodList) error {
	ginkgo.By("trying to dial each unique pod")
	label := labels.SelectorFromSet(labels.Set(map[string]string{"name": name}))
	return wait.PollImmediate(poll, podRespondingTimeout, NewProxyResponseChecker(c, ns, label, name, wantName, pods).CheckAllResponses)
}

// WaitForControlledPodsRunning waits up to 10 minutes for pods to become Running.
func WaitForControlledPodsRunning(c clientset.Interface, ns, name string, kind schema.GroupKind) error {
	rtObject, err := e2eresource.GetRuntimeObjectForKind(c, kind, ns, name)
	if err != nil {
		return err
	}
	selector, err := e2eresource.GetSelectorFromRuntimeObject(rtObject)
	if err != nil {
		return err
	}
	replicas, err := e2eresource.GetReplicasFromRuntimeObject(rtObject)
	if err != nil {
		return err
	}
	err = testutils.WaitForEnoughPodsWithLabelRunning(c, ns, selector, int(replicas))
	if err != nil {
		return fmt.Errorf("Error while waiting for replication controller %s pods to be running: %v", name, err)
	}
	return nil
}

// WaitForControlledPods waits up to podListTimeout for getting pods of the specified controller name and return them.
func WaitForControlledPods(c clientset.Interface, ns, name string, kind schema.GroupKind) (pods *v1.PodList, err error) {
	rtObject, err := e2eresource.GetRuntimeObjectForKind(c, kind, ns, name)
	if err != nil {
		return nil, err
	}
	selector, err := e2eresource.GetSelectorFromRuntimeObject(rtObject)
	if err != nil {
		return nil, err
	}
	return WaitForPodsWithLabel(c, ns, selector)
}

// WaitForPodsWithLabelScheduled waits for all matching pods to become scheduled and at least one
// matching pod exists.  Return the list of matching pods.
func WaitForPodsWithLabelScheduled(c clientset.Interface, ns string, label labels.Selector) (pods *v1.PodList, err error) {
	err = wait.PollImmediate(poll, podScheduledBeforeTimeout,
		func() (bool, error) {
			pods, err = WaitForPodsWithLabel(c, ns, label)
			if err != nil {
				return false, err
			}
			for _, pod := range pods.Items {
				if pod.Spec.NodeName == "" {
					return false, nil
				}
			}
			return true, nil
		})
	return pods, err
}

// WaitForPodsWithLabel waits up to podListTimeout for getting pods with certain label
func WaitForPodsWithLabel(c clientset.Interface, ns string, label labels.Selector) (pods *v1.PodList, err error) {
	for t := time.Now(); time.Since(t) < podListTimeout; time.Sleep(poll) {
		options := metav1.ListOptions{LabelSelector: label.String()}
		pods, err = c.CoreV1().Pods(ns).List(context.TODO(), options)
		if err != nil {
			if testutils.IsRetryableAPIError(err) {
				continue
			}
			return
		}
		if len(pods.Items) > 0 {
			break
		}
	}
	if pods == nil || len(pods.Items) == 0 {
		err = fmt.Errorf("Timeout while waiting for pods with label %v", label)
	}
	return
}

// WaitForPodsWithLabelRunningReady waits for exact amount of matching pods to become running and ready.
// Return the list of matching pods.
func WaitForPodsWithLabelRunningReady(c clientset.Interface, ns string, label labels.Selector, num int, timeout time.Duration) (pods *v1.PodList, err error) {
	var current int
	err = wait.Poll(poll, timeout,
		func() (bool, error) {
			pods, err = WaitForPodsWithLabel(c, ns, label)
			if err != nil {
				e2elog.Logf("Failed to list pods: %v", err)
				if testutils.IsRetryableAPIError(err) {
					return false, nil
				}
				return false, err
			}
			current = 0
			for _, pod := range pods.Items {
				if flag, err := testutils.PodRunningReady(&pod); err == nil && flag == true {
					current++
				}
			}
			if current != num {
				e2elog.Logf("Got %v pods running and ready, expect: %v", current, num)
				return false, nil
			}
			return true, nil
		})
	return pods, err
}

// WaitForPodsReady waits for the pods to become ready.
func WaitForPodsReady(c clientset.Interface, ns, name string, minReadySeconds int) error {
	label := labels.SelectorFromSet(labels.Set(map[string]string{"name": name}))
	options := metav1.ListOptions{LabelSelector: label.String()}
	return wait.Poll(poll, 5*time.Minute, func() (bool, error) {
		pods, err := c.CoreV1().Pods(ns).List(context.TODO(), options)
		if err != nil {
			return false, nil
		}
		for _, pod := range pods.Items {
			if !podutil.IsPodAvailable(&pod, int32(minReadySeconds), metav1.Now()) {
				return false, nil
			}
		}
		return true, nil
	})
}

// WaitForNRestartablePods tries to list restarting pods using ps until it finds expect of them,
// returning their names if it can do so before timeout.
func WaitForNRestartablePods(ps *testutils.PodStore, expect int, timeout time.Duration) ([]string, error) {
	var pods []*v1.Pod
	var errLast error
	found := wait.Poll(poll, timeout, func() (bool, error) {
		allPods := ps.List()
		pods = FilterNonRestartablePods(allPods)
		if len(pods) != expect {
			errLast = fmt.Errorf("expected to find %d pods but found only %d", expect, len(pods))
			e2elog.Logf("Error getting pods: %v", errLast)
			return false, nil
		}
		return true, nil
	}) == nil
	podNames := make([]string, len(pods))
	for i, p := range pods {
		podNames[i] = p.ObjectMeta.Name
	}
	if !found {
		return podNames, fmt.Errorf("couldn't find %d pods within %v; last error: %v",
			expect, timeout, errLast)
	}
	return podNames, nil
}