Files
fission-src/executor/poolmgr/gp.go
T
Ta-Ching ChenandGitHub 37846a5827 Fix requests are sent to unready function pod (newdeploy) (#1005)
* Refactor specialization process
* Separate readiness and liveness probe to different routes

For newdeploy, readiness probe should check whether a fetcher specializes env container successfully or not. In this commit, fetcher returns the actual state of current specialization status instead of returning 200ok directly.
2018-12-27 16:29:31 +08:00

735 lines
23 KiB
Go

/*
Copyright 2016 The Fission 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 poolmgr
import (
"fmt"
"log"
"math/rand"
"net"
"os"
"path/filepath"
"strings"
"time"
"github.com/dchest/uniuri"
"github.com/pkg/errors"
apiv1 "k8s.io/api/core/v1"
"k8s.io/api/extensions/v1beta1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/util/intstr"
"k8s.io/client-go/kubernetes"
"github.com/fission/fission"
"github.com/fission/fission/crd"
fetcherClient "github.com/fission/fission/environments/fetcher/client"
"github.com/fission/fission/executor/fscache"
"github.com/fission/fission/executor/util"
)
type (
GenericPool struct {
env *crd.Environment
replicas int32 // num idle pods
deployment *v1beta1.Deployment // kubernetes deployment
namespace string // namespace to keep our resources
functionNamespace string // fallback namespace for fission functions
podReadyTimeout time.Duration // timeout for generic pods to become ready
idlePodReapTime time.Duration // pods unused for idlePodReapTime are deleted
fsCache *fscache.FunctionServiceCache // cache funcSvc's by function, address and podname
useSvc bool // create k8s service for specialized pods
useIstio bool
poolInstanceId string // small random string to uniquify pod names
fetcherImage string
fetcherImagePullPolicy apiv1.PullPolicy
runtimeImagePullPolicy apiv1.PullPolicy // pull policy for generic pool to created env deployment
kubernetesClient *kubernetes.Clientset
fissionClient *crd.FissionClient
instanceId string // poolmgr instance id
labelsForPool map[string]string
requestChannel chan *choosePodRequest
sharedMountPath string // used by generic pool when creating env deployment to specify the share volume path for fetcher & env
sharedSecretPath string
sharedCfgMapPath string
}
// serialize the choosing of pods so that choices don't conflict
choosePodRequest struct {
newLabels map[string]string
responseChannel chan *choosePodResponse
}
choosePodResponse struct {
pod *apiv1.Pod
error
}
)
func MakeGenericPool(
fissionClient *crd.FissionClient,
kubernetesClient *kubernetes.Clientset,
env *crd.Environment,
initialReplicas int32,
namespace string,
functionNamespace string,
fsCache *fscache.FunctionServiceCache,
instanceId string,
enableIstio bool) (*GenericPool, error) {
log.Printf("Creating pool for environment %v", env.Metadata)
fetcherImage := os.Getenv("FETCHER_IMAGE")
if len(fetcherImage) == 0 {
fetcherImage = "fission/fetcher"
}
// TODO: in general we need to provide the user a way to configure pools. Initial
// replicas, autoscaling params, various timeouts, etc.
gp := &GenericPool{
env: env,
replicas: initialReplicas, // TODO make this an env param instead?
requestChannel: make(chan *choosePodRequest),
fissionClient: fissionClient,
kubernetesClient: kubernetesClient,
namespace: namespace,
functionNamespace: functionNamespace,
podReadyTimeout: 5 * time.Minute, // TODO make this an env param?
idlePodReapTime: 3 * time.Minute, // TODO make this configurable
fsCache: fsCache,
poolInstanceId: uniuri.NewLen(8),
instanceId: instanceId,
fetcherImage: fetcherImage,
useSvc: false, // defaults off -- svc takes a second or more to become routable, slowing cold start
useIstio: enableIstio, // defaults off -- istio integration requires pod relabeling and it takes a second or more to become routable, slowing cold start
sharedMountPath: "/userfunc", // change this may break v1 compatibility, since most of the v1 environments have hard-coded "/userfunc" in loading path
sharedSecretPath: "/secrets",
sharedCfgMapPath: "/configs",
}
gp.runtimeImagePullPolicy = fission.GetImagePullPolicy(os.Getenv("RUNTIME_IMAGE_PULL_POLICY"))
gp.fetcherImagePullPolicy = fission.GetImagePullPolicy(os.Getenv("FETCHER_IMAGE_PULL_POLICY"))
log.Printf("fetcher image: %v, pull policy: %v", gp.fetcherImage, gp.fetcherImagePullPolicy)
// create fetcher SA in this ns, if not already created
_, err := fission.SetupSA(gp.kubernetesClient, fission.FissionFetcherSA, gp.namespace)
if err != nil {
log.Printf("Error : %v creating fetcher SA in ns : %s", err, gp.namespace)
return nil, err
}
// Labels for generic deployment/RS/pods.
gp.labelsForPool = gp.getDeployLabels()
// create the pool
err = gp.createPool()
if err != nil {
return nil, err
}
log.Printf("[%v] Deployment created", env.Metadata)
go gp.choosePodService()
return gp, nil
}
func (gp *GenericPool) getDeployLabels() map[string]string {
return map[string]string{
fission.EXECUTOR_INSTANCEID_LABEL: gp.instanceId,
fission.EXECUTOR_TYPE: fission.ExecutorTypePoolmgr,
fission.ENVIRONMENT_NAME: gp.env.Metadata.Name,
fission.ENVIRONMENT_NAMESPACE: gp.env.Metadata.Namespace,
fission.ENVIRONMENT_UID: string(gp.env.Metadata.UID),
}
}
// choosePodService serializes the choosing of pods
func (gp *GenericPool) choosePodService() {
for {
select {
case req := <-gp.requestChannel:
pod, err := gp._choosePod(req.newLabels)
if err != nil {
req.responseChannel <- &choosePodResponse{error: err}
continue
}
req.responseChannel <- &choosePodResponse{pod: pod}
}
}
}
// choosePod picks a ready pod from the pool and relabels it, waiting if necessary.
// returns the pod API object.
func (gp *GenericPool) choosePod(newLabels map[string]string) (*apiv1.Pod, error) {
req := &choosePodRequest{
newLabels: newLabels,
responseChannel: make(chan *choosePodResponse),
}
gp.requestChannel <- req
resp := <-req.responseChannel
return resp.pod, resp.error
}
// _choosePod is called serially by choosePodService
func (gp *GenericPool) _choosePod(newLabels map[string]string) (*apiv1.Pod, error) {
startTime := time.Now()
for {
// Retries took too long, error out.
if time.Since(startTime) > gp.podReadyTimeout {
log.Printf("[%v] Erroring out, timed out", newLabels)
return nil, errors.New("timeout: waited too long to get a ready pod")
}
// Get pods; filter the ones that are ready
podList, err := gp.kubernetesClient.CoreV1().Pods(gp.namespace).List(
metav1.ListOptions{
LabelSelector: labels.Set(
gp.deployment.Spec.Selector.MatchLabels).AsSelector().String(),
})
if err != nil {
return nil, err
}
readyPods := make([]*apiv1.Pod, 0, len(podList.Items))
for i := range podList.Items {
pod := podList.Items[i]
// Ignore not ready pod here
if !fission.IsReadyPod(&pod) {
continue
}
// add it to the list of ready pods
readyPods = append(readyPods, &pod)
}
log.Printf("[%v] found %v ready pods of %v total", newLabels, len(readyPods), len(podList.Items))
// If there are no ready pods, wait and retry.
if len(readyPods) == 0 {
err = gp.waitForReadyPod()
if err != nil {
return nil, err
}
continue
}
// Pick a ready pod. For now just choose randomly;
// ideally we'd care about which node it's running on,
// and make a good scheduling decision.
chosenPod := readyPods[rand.Intn(len(readyPods))]
if gp.env.Spec.AllowedFunctionsPerContainer != fission.AllowedFunctionsPerContainerInfinite {
// Relabel. If the pod already got picked and
// modified, this should fail; in that case just
// retry.
chosenPod.ObjectMeta.Labels = newLabels
log.Printf("relabeling pod: [%v]", chosenPod.ObjectMeta.Name)
_, err = gp.kubernetesClient.CoreV1().Pods(gp.namespace).Update(chosenPod)
if err != nil {
log.Printf("failed to relabel pod [%v]: %v", chosenPod.ObjectMeta.Name, err)
continue
}
}
log.Printf("Chosen pod: %v (in %v)", chosenPod.ObjectMeta.Name, time.Since(startTime))
return chosenPod, nil
}
}
func (gp *GenericPool) labelsForFunction(metadata *metav1.ObjectMeta) map[string]string {
return map[string]string{
"functionName": metadata.Name,
"functionUid": string(metadata.UID),
"unmanaged": "true", // this allows us to easily find pods not managed by the deployment
fission.EXECUTOR_INSTANCEID_LABEL: gp.instanceId,
}
}
func (gp *GenericPool) scheduleDeletePod(name string) {
go func() {
// The sleep allows debugging or collecting logs from the pod before it's
// cleaned up. (We need a better solutions for both those things; log
// aggregation and storage will help.)
log.Printf("Error in pod '%v', scheduling cleanup", name)
// Ignore sleep here if istio feature is enabled, function pod
// will be deleted after 6 mins (terminationGracePeriodSeconds).
if !gp.useIstio {
time.Sleep(5 * time.Minute)
}
gp.kubernetesClient.CoreV1().Pods(gp.namespace).Delete(name, nil)
}()
}
func IsIPv6(podIP string) bool {
ip := net.ParseIP(podIP)
return ip != nil && strings.Contains(podIP, ":")
}
func (gp *GenericPool) getSpecializeUrl(podIP string) string {
testUrl := os.Getenv("TEST_SPECIALIZE_URL")
if len(testUrl) != 0 {
// it takes a second or so for the test service to
// become routable once a pod is relabeled. This is
// super hacky, but only runs in unit tests.
time.Sleep(5 * time.Second)
return testUrl
}
isv6 := IsIPv6(podIP)
var baseUrl string
if isv6 == false {
baseUrl = fmt.Sprintf("http://%v:8000/", podIP)
} else if isv6 == true { // We use bracket if the IP is in IPv6.
baseUrl = fmt.Sprintf("http://[%v]:8000/", podIP)
}
return baseUrl
}
// specializePod chooses a pod, copies the required user-defined function to that pod
// (via fetcher), and calls the function-run container to load it, resulting in a
// specialized pod.
func (gp *GenericPool) specializePod(pod *apiv1.Pod, metadata *metav1.ObjectMeta) error {
// for fetcher we don't need to create a service, just talk to the pod directly
podIP := pod.Status.PodIP
if len(podIP) == 0 {
return errors.New("Pod has no IP")
}
// specialize pod with service
if gp.useIstio {
svc := fission.GetFunctionIstioServiceName(metadata.Name, metadata.Namespace)
podIP = fmt.Sprintf("%v.%v", svc, gp.namespace)
}
// tell fetcher to get the function.
fetcherUrl := gp.getSpecializeUrl(podIP)
log.Printf("[%v] calling fetcher to copy function with fetcher url: %v", metadata.Name, fetcherUrl)
fn, err := gp.fissionClient.
Functions(metadata.Namespace).
Get(metadata.Name)
if err != nil {
return err
}
// for backward compatibility, since most v1 env
// still try to load user function from hard coded
// path /userfunc/user
targetFilename := "user"
if gp.env.Spec.Version == 2 {
targetFilename = string(fn.Metadata.UID)
}
specializeReq := fission.FunctionSpecializeRequest{
FetchReq: fission.FunctionFetchRequest{
FetchType: fission.FETCH_DEPLOYMENT,
Package: metav1.ObjectMeta{
Namespace: fn.Spec.Package.PackageRef.Namespace,
Name: fn.Spec.Package.PackageRef.Name,
},
Filename: targetFilename,
Secrets: fn.Spec.Secrets,
ConfigMaps: fn.Spec.ConfigMaps,
KeepArchive: gp.env.Spec.KeepArchive,
},
LoadReq: fission.FunctionLoadRequest{
FilePath: filepath.Join(gp.sharedMountPath, targetFilename),
FunctionName: fn.Spec.Package.FunctionName,
FunctionMetadata: &fn.Metadata,
EnvVersion: gp.env.Spec.Version,
},
}
log.Printf("[%v] specializing pod", metadata.Name)
err = fetcherClient.MakeClient(fetcherUrl).Specialize(&specializeReq)
if err != nil {
return err
}
return nil
}
func (gp *GenericPool) getPoolName() string {
// Use executor type as delimiter between function name and namespace to prevent deployment name conflict.
// For example:
// 1. fn-name: a-b fn-namespace: c => a-b-poolmgr-c
// 2. fn-name: a fn-namespace: b-c => a-poolmgr-b-c
return strings.ToLower(fmt.Sprintf("%v-poolmgr-%v", gp.env.Metadata.Name, gp.env.Metadata.Namespace))
}
// A pool is a deployment of generic containers for an env. This
// creates the pool but doesn't wait for any pods to be ready.
func (gp *GenericPool) createPool() error {
fetcherResources, err := util.GetFetcherResources()
if err != nil {
return err
}
// Use long terminationGracePeriodSeconds for connection draining in case that
// pod still runs user functions.
gracePeriodSeconds := int64(6 * 60)
if gp.env.Spec.TerminationGracePeriod > 0 {
gracePeriodSeconds = gp.env.Spec.TerminationGracePeriod
}
podAnnotations := gp.env.Metadata.Annotations
if podAnnotations == nil {
podAnnotations = make(map[string]string)
}
if gp.useIstio && gp.env.Spec.AllowAccessToExternalNetwork {
podAnnotations["sidecar.istio.io/inject"] = "false"
}
deployment := &v1beta1.Deployment{
ObjectMeta: metav1.ObjectMeta{
Name: gp.getPoolName(),
Labels: gp.labelsForPool,
},
Spec: v1beta1.DeploymentSpec{
Replicas: &gp.replicas,
Selector: &metav1.LabelSelector{
MatchLabels: gp.labelsForPool,
},
Template: apiv1.PodTemplateSpec{
ObjectMeta: metav1.ObjectMeta{
Labels: gp.labelsForPool,
Annotations: podAnnotations,
},
Spec: apiv1.PodSpec{
Volumes: []apiv1.Volume{
{
Name: fission.SharedVolumeUserfunc,
VolumeSource: apiv1.VolumeSource{
EmptyDir: &apiv1.EmptyDirVolumeSource{},
},
},
{
Name: fission.SharedVolumeSecrets,
VolumeSource: apiv1.VolumeSource{
EmptyDir: &apiv1.EmptyDirVolumeSource{},
},
},
{
Name: fission.SharedVolumeConfigmaps,
VolumeSource: apiv1.VolumeSource{
EmptyDir: &apiv1.EmptyDirVolumeSource{},
},
},
},
Containers: []apiv1.Container{
fission.MergeContainerSpecs(&apiv1.Container{
Name: gp.env.Metadata.Name,
Image: gp.env.Spec.Runtime.Image,
ImagePullPolicy: gp.runtimeImagePullPolicy,
TerminationMessagePath: "/dev/termination-log",
VolumeMounts: []apiv1.VolumeMount{
{
Name: fission.SharedVolumeUserfunc,
MountPath: gp.sharedMountPath,
},
{
Name: fission.SharedVolumeSecrets,
MountPath: gp.sharedSecretPath,
},
{
Name: fission.SharedVolumeConfigmaps,
MountPath: gp.sharedCfgMapPath,
},
},
Resources: gp.env.Spec.Resources,
// Pod is removed from endpoints list for service when it's
// state became "Termination". We used preStop hook as the
// workaround for connection draining since pod maybe shutdown
// before grace period expires.
// https://kubernetes.io/docs/concepts/workloads/pods/pod/#termination-of-pods
// https://github.com/kubernetes/kubernetes/issues/47576#issuecomment-308900172
Lifecycle: &apiv1.Lifecycle{
PreStop: &apiv1.Handler{
Exec: &apiv1.ExecAction{
Command: []string{
"sleep",
fmt.Sprintf("%v", gracePeriodSeconds),
},
},
},
},
}, gp.env.Spec.Runtime.Container),
{
Name: "fetcher",
Image: gp.fetcherImage,
ImagePullPolicy: gp.fetcherImagePullPolicy,
TerminationMessagePath: "/dev/termination-log",
VolumeMounts: []apiv1.VolumeMount{
{
Name: fission.SharedVolumeUserfunc,
MountPath: gp.sharedMountPath,
},
{
Name: fission.SharedVolumeSecrets,
MountPath: gp.sharedSecretPath,
},
{
Name: fission.SharedVolumeConfigmaps,
MountPath: gp.sharedCfgMapPath,
},
},
Resources: fetcherResources,
Command: []string{"/fetcher",
"-secret-dir", gp.sharedSecretPath,
"-cfgmap-dir", gp.sharedCfgMapPath,
gp.sharedMountPath},
// Pod is removed from endpoints list for service when it's
// state became "Termination". We used preStop hook as the
// workaround for connection draining since pod maybe shutdown
// before grace period expires.
// https://kubernetes.io/docs/concepts/workloads/pods/pod/#termination-of-pods
// https://github.com/kubernetes/kubernetes/issues/47576#issuecomment-308900172
Lifecycle: &apiv1.Lifecycle{
PreStop: &apiv1.Handler{
Exec: &apiv1.ExecAction{
Command: []string{
"sleep",
fmt.Sprintf("%v", gracePeriodSeconds),
},
},
},
},
ReadinessProbe: &apiv1.Probe{
InitialDelaySeconds: 1,
PeriodSeconds: 1,
FailureThreshold: 30,
Handler: apiv1.Handler{
HTTPGet: &apiv1.HTTPGetAction{
Path: "/readniess-healthz",
Port: intstr.IntOrString{
Type: intstr.Int,
IntVal: 8000,
},
},
},
},
LivenessProbe: &apiv1.Probe{
InitialDelaySeconds: 1,
PeriodSeconds: 5,
Handler: apiv1.Handler{
HTTPGet: &apiv1.HTTPGetAction{
Path: "/healthz",
Port: intstr.IntOrString{
Type: intstr.Int,
IntVal: 8000,
},
},
},
},
},
},
ServiceAccountName: "fission-fetcher",
// TerminationGracePeriodSeconds should be equal to the
// sleep time of preStop to make sure that SIGTERM is sent
// to pod after 6 mins.
TerminationGracePeriodSeconds: &gracePeriodSeconds,
},
},
},
}
depl, err := gp.kubernetesClient.ExtensionsV1beta1().Deployments(gp.namespace).Create(deployment)
if err != nil {
log.Printf("Error creating deployment for %s in kubernetes, err: %v", deployment.Name, err)
return err
}
gp.deployment = depl
return nil
}
func (gp *GenericPool) waitForReadyPod() error {
startTime := time.Now()
for {
// TODO: for now we just poll; use a watch instead
depl, err := gp.kubernetesClient.ExtensionsV1beta1().Deployments(gp.namespace).Get(
gp.deployment.ObjectMeta.Name, metav1.GetOptions{})
if err != nil {
err = errors.Wrap(err, fmt.Sprintf(
"Error waiting for ready pod of deployment %v in namespace %v",
gp.deployment.ObjectMeta.Name, gp.namespace))
log.Print(err)
return err
}
gp.deployment = depl
if gp.deployment.Status.AvailableReplicas > 0 {
return nil
}
if time.Since(startTime) > gp.podReadyTimeout {
return errors.Errorf(
"Timeout: waited too long for pod of deployment %v in namespace %v to be ready",
gp.deployment.ObjectMeta.Name, gp.namespace)
}
time.Sleep(1000 * time.Millisecond)
}
}
func (gp *GenericPool) createSvc(name string, labels map[string]string) (*apiv1.Service, error) {
service := apiv1.Service{
ObjectMeta: metav1.ObjectMeta{
Name: name,
},
Spec: apiv1.ServiceSpec{
Type: apiv1.ServiceTypeClusterIP,
Ports: []apiv1.ServicePort{
{
Protocol: apiv1.ProtocolTCP,
Port: 80,
TargetPort: intstr.FromInt(8888),
},
},
Selector: labels,
},
}
svc, err := gp.kubernetesClient.CoreV1().Services(gp.namespace).Create(&service)
return svc, err
}
func (gp *GenericPool) GetFuncSvc(m *metav1.ObjectMeta) (*fscache.FuncSvc, error) {
log.Printf("[%v] Choosing pod from pool", m.Name)
newLabels := gp.labelsForFunction(m)
if gp.useIstio {
// Istio only allows accessing pod through k8s service, and requests come to
// service are not always being routed to the same pod. For example:
// If there is only one pod (podA) behind the service svcX.
// svcX -> podA
// All requests (specialize request & function access requests)
// will be routed to podA without any problem.
// If podA and podB are behind svcX.
// svcX -> podA (specialized)
// -> podB (non-specialized)
// The specialize request may be routed to podA and the function access
// requests may go to podB. In this case, the function cannot be served
// properly.
// To prevent such problem, we need to delete old versions function pods
// and make sure that there is only one pod behind the service
sel := map[string]string{
"functionName": m.Name,
"functionUid": string(m.UID),
}
podList, err := gp.kubernetesClient.CoreV1().Pods(gp.namespace).List(metav1.ListOptions{
LabelSelector: labels.Set(sel).AsSelector().String(),
})
if err != nil {
return nil, err
}
// Remove old versions function pods
for _, pod := range podList.Items {
// Delete pod no matter what status it is
gp.kubernetesClient.CoreV1().Pods(gp.namespace).Delete(pod.ObjectMeta.Name, nil)
}
}
pod, err := gp.choosePod(newLabels)
if err != nil {
return nil, err
}
err = gp.specializePod(pod, m)
if err != nil {
gp.scheduleDeletePod(pod.ObjectMeta.Name)
return nil, err
}
log.Printf("Specialized pod: %v", pod.ObjectMeta.Name)
var svcHost string
if gp.useSvc && !gp.useIstio {
svcName := fmt.Sprintf("svc-%v", m.Name)
if len(m.UID) > 0 {
svcName = fmt.Sprintf("%s-%v", svcName, m.UID)
}
labels := gp.labelsForFunction(m)
svc, err := gp.createSvc(svcName, labels)
if err != nil {
gp.scheduleDeletePod(pod.ObjectMeta.Name)
return nil, err
}
if svc.ObjectMeta.Name != svcName {
gp.scheduleDeletePod(pod.ObjectMeta.Name)
return nil, errors.New(fmt.Sprintf("sanity check failed for svc %v", svc.ObjectMeta.Name))
}
// the fission router isn't in the same namespace, so return a
// namespace-qualified hostname
svcHost = fmt.Sprintf("%v.%v", svcName, gp.namespace)
} else if gp.useIstio {
svc := fission.GetFunctionIstioServiceName(m.Name, m.Namespace)
svcHost = fmt.Sprintf("%v.%v:8888", svc, gp.namespace)
} else {
log.Printf("Using pod IP for specialized pod")
svcHost = fmt.Sprintf("%v:8888", pod.Status.PodIP)
}
kubeObjRefs := []apiv1.ObjectReference{
{
Kind: "pod",
Name: pod.ObjectMeta.Name,
APIVersion: pod.TypeMeta.APIVersion,
Namespace: pod.ObjectMeta.Namespace,
ResourceVersion: pod.ObjectMeta.ResourceVersion,
UID: pod.ObjectMeta.UID,
},
}
fsvc := &fscache.FuncSvc{
Name: pod.ObjectMeta.Name,
Function: m,
Environment: gp.env,
Address: svcHost,
KubernetesObjects: kubeObjRefs,
Executor: fscache.POOLMGR,
Ctime: time.Now(),
Atime: time.Now(),
}
_, err = gp.fsCache.Add(*fsvc)
if err != nil {
return nil, err
}
return fsvc, nil
}
// destroys the pool -- the deployment, replicaset and pods
func (gp *GenericPool) destroy() error {
deletePropagation := metav1.DeletePropagationBackground
delOpt := metav1.DeleteOptions{
PropagationPolicy: &deletePropagation,
}
err := gp.kubernetesClient.ExtensionsV1beta1().
Deployments(gp.namespace).Delete(gp.deployment.ObjectMeta.Name, &delOpt)
if err != nil {
log.Printf("Error destroying deployment: %v", err)
return err
}
return nil
}