问题背景
背景是这样的，我有一套测试用的K8S集群，发现无法正常删除命名空间了，一直处于Terminating状态，强制删除也不行。于是，再次手动创建了一个名为“test-b”的命名空间，同样也是不能正常删除。于是，展开了排查。不过，查到最后，发现是个毫无技术含量的“乌龙问题”。结果不重要，重要的是我想把这个过程分享一下。
排查过程
- 正常删除命名空间时，一直处于阻塞状态，只能Ctrl C掉
[root@k8s-b-master ~]# kubectl delete ns test-b
namespace "test-b" deleted- 查看状态一直处于Terminating状态
[root@k8s-b-master ~]# kubectl get ns
test-b Terminating 18h- 尝试强制删除，也是一直处于阻塞状态，也只能Ctrl C掉
[root@k8s-b-master ~]# kubectl delete namespace test-b --grace-period=0 --force- 查看详细信息发现
[root@k8s-b-master ~]# kubectl describe ns test-b
Name: test-b
Labels: kubernetes.io/metadata.name=test-b
Annotations: <none>
Status: Terminating
Conditions:
Type Status LastTransitionTime Reason Message
---- ------ ------------------ ------ -------
NamespaceDeletionDiscoveryFailure True Fri, 05 May 2023 14:06:52 0800 DiscoveryFailed Discovery failed for some groups, 1 failing: unable to retrieve the complete list of server APIs: metrics.k8s.io/v1beta1: the server is currently unable to handle the request
NamespaceDeletionGroupVersionParsingFailure False Fri, 05 May 2023 14:06:52 0800 ParsedGroupVersions All legacy kube types successfully parsed
NamespaceDeletionContentFailure False Fri, 05 May 2023 14:06:52 0800 ContentDeleted All content successfully deleted, may be waiting on finalization
NamespaceContentRemaining False Fri, 05 May 2023 14:06:52 0800 ContentRemoved All content successfully removed
NamespaceFinalizersRemaining False Fri, 05 May 2023 14:06:52 0800 ContentHasNoFinalizers All content-preserving finalizers finished
No resource quota.
No LimitRange resource.问题出在这里：DiscoveryFailed：Discovery failed for some groups, 1 failing: unable to retrieve the complete list of server APIs: metrics.k8s.io/v1beta1: the server is currently unable to handle the request
难道API Server出问题了？于是继续排查。
- 检查API Server是否正常运行
[root@k8s-b-master ~]# kubectl get componentstatus
Warning: v1 ComponentStatus is deprecated in v1.19
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
etcd-0 Healthy {"health":"true","reason":""}
scheduler Healthy ok 从输出来看，controller-manager、scheduler和etcd集群都处于正常状态（Healthy）。
- 继续检查API Server的日志看看是否有错误或异常
# 获取API Server Pod的名称：
[root@k8s-b-master ~]# kubectl get pods -n kube-system -l component=kube-apiserver -o name
pod/kube-apiserver-k8s-b-master
# 查看API Server的日志：
[root@k8s-b-master ~]# kubectl get pods -n kube-system -l component=kube-apiserver -o name
pod/kube-apiserver-k8s-b-master
[root@k8s-b-master ~]# kubectl logs -n kube-system kube-apiserver-k8s-b-master
...
...
W0506 01:00:12.965627 1 handler_proxy.go:105] no RequestInfo found in the context
E0506 01:00:12.965711 1 controller.go:116] loading OpenAPI spec for "v1beta1.metrics.k8s.io" failed with: failed to retrieve openAPI spec, http error: ResponseCode: 503, Body: service unavailable
, Header: map[Content-Type:[text/plain; charset=utf-8] X-Content-Type-Options:[nosniff]]
I0506 01:00:12.965722 1 controller.go:129] OpenAPI AggregationController: action for item v1beta1.metrics.k8s.io: Rate Limited Requeue.
W0506 01:00:12.968678 1 handler_proxy.go:105] no RequestInfo found in the context
E0506 01:00:12.968709 1 controller.go:113] loading OpenAPI spec for "v1beta1.metrics.k8s.io" failed with: Error, could not get list of group versions for APIService
I0506 01:00:12.968719 1 controller.go:126] OpenAPI AggregationController: action for item v1beta1.metrics.k8s.io: Rate Limited Requeue.
I0506 01:00:43.794546 1 controller.go:616] quota admission added evaluator for: endpointslices.discovery.k8s.io
I0506 01:00:44.023629 1 controller.go:616] quota admission added evaluator for: endpoints
W0506 01:01:12.965985 1 handler_proxy.go:105] no RequestInfo found in the context
E0506 01:01:12.966062 1 controller.go:116] loading OpenAPI spec for "v1beta1.metrics.k8s.io" failed with: failed to retrieve openAPI spec, http error: ResponseCode: 503, Body: service unavailable
, Header: map[Content-Type:[text/plain; charset=utf-8] X-Content-Type-Options:[nosniff]]
I0506 01:01:12.966069 1 controller.go:129] OpenAPI AggregationController: action for item v1beta1.metrics.k8s.io: Rate Limited Requeue.
W0506 01:01:12.969496 1 handler_proxy.go:105] no RequestInfo found in the context
E0506 01:01:12.969527 1 controller.go:113] loading OpenAPI spec for "v1beta1.metrics.k8s.io" failed with: Error, could not get list of group versions for APIService
...
...
# 后面都是这样的Log
...
...从输出日志来看，问题似乎与metrics.k8s.io/v1beta1有关，这个API被用于收集Kubernetes集群的度量数据。可能是因为度量服务器(metrics-server)出现故障，无法满足API Server的请求，导致API Server无法处理请求。
- k8s默认是没有metrics-server组件的呀，还是看看：
[root@k8s-b-master ~]# kubectl get pods -n kube-system -l k8s-app=metrics-server
No resources found in kube-system namespace.kube-system命名空间中没有找到标签为k8s-app=metrics-server的Pod，这很正常呀，K8S本来就是默认没有安装Metrics Server 组件的，为什么现在又依赖了？
查到这里，我突然想起了前段时间部署过kube-prometheus，当时kube-state-metrics拉取镜像失败没有正常运行，因为是临时测试环境，后来就没管了，时间一长居然把这事给忘了。
于是看了一下，发现还真是：
代码语言：txt复制[root@k8s-b-master ~]# kubectl get pod -n monitoring
NAME READY STATUS RESTARTS AGE
alertmanager-main-0 2/2 Running 14 (30m ago) 5d19h
alertmanager-main-1 2/2 Running 14 (29m ago) 5d19h
alertmanager-main-2 2/2 Running 14 (29m ago) 5d19h
blackbox-exporter-69f4d86566-wn6q7 3/3 Running 21 (30m ago) 5d19h
grafana-56c4977497-2rjmt 1/1 Running 7 (29m ago) 5d19h
kube-state-metrics-56f8746666-lsps6 2/3 ImagePullBackOff 14 (29m ago) 5d19h # 拉取镜像失败导致没有正常运行
node-exporter-d8c5k 2/2 Running 14 (30m ago) 5d19h
node-exporter-gvfx2 2/2 Running 14 (30m ago) 5d19h
node-exporter-gxccx 2/2 Running 14 (29m ago) 5d19h
node-exporter-h292z 2/2 Running 14 (30m ago) 5d19h
node-exporter-mztj6 2/2 Running 14 (29m ago) 5d19h
node-exporter-rvfz6 2/2 Running 14 (29m ago) 5d19h
node-exporter-twg9q 2/2 Running 13 (29m ago) 5d19h
prometheus-adapter-77f56b865b-76nzk 0/1 ImagePullBackOff 0 5d19h
prometheus-adapter-77f56b865b-wbcwl 0/1 ImagePullBackOff 0 5d19h
prometheus-k8s-0 2/2 Running 14 (30m ago) 5d19h
prometheus-k8s-1 2/2 Running 14 (29m ago) 5d19h
prometheus-operator-788dd7cb76-85zwj 2/2 Running 14 (29m ago) 5d19h反正也不用这套环境了，干它：
代码语言：txt复制[root@k8s-b-master ~]# kubectl delete -f kube-prometheus-main/manifests/
[root@k8s-b-master ~]# kubectl delete -f kube-prometheus-main/manifests/setup/再次查看命名空间，test-b这个命名空间也随之能正常删除掉了，问题解决：
代码语言：txt复制[root@k8s-b-master ~]# kubectl get ns
NAME STATUS AGE
default Active 5d22h
kube-node-lease Active 5d22h
kube-public Active 5d22h
kube-system Active 5d22h
[root@k8s-b-master ~]# 最后的觉悟
结合官方文档相关资料和自己平常的经验反思了一下这个事情，kube-state-metrics 组件是负责监控 K8S 集群的状态，并且它会定期获取集群内各个资源的指标数据，这些指标数据会被 Metrics Server 组件使用。当 kube-state-metrics 组件无法正常工作时，Metrics Server 组件就无法获取到指标数据，从而导致 Metrics Server 组件无法正常运行。在 K8S 集群中，很多组件都会使用 Metrics Server 组件提供的指标数据，例如 HPA、kubelet 等。如果 Metrics Server 组件无法正常运行，可能会导致其他组件出现问题，包括删除命名空间时提示错误。也就是说 Metrics Server 组件无法正常运行，导致了API Server组件在处理其它一些请求时可能会失败，从而发生了无法正常删除命名空间的情况。
