容器編排系統K8s之APIService資源

1874發表於2021-01-15

　　前文我們聊到了k8s上crd資源的使用和相關說明，回顧請參考：https://www.cnblogs.com/qiuhom-1874/p/14267400.html；今天我們來了解下k8s的第二種擴充套件機制自定義apiserver，以及apiservice資源的相關話題；

　　在開始聊自定義apiserver前，我們先來了解下k8s原生的apiserver；其實apiserver就是一個https伺服器，我們可以使用kubectl工具通過https協議請求apiserver建立資源，刪除資源，檢視資源等等操作；每個請求都對應著RESTful api中的請求方法，對應資源就是http協議中的url路徑；比如我們要建立一個pod，其kubectl請求apiserver 使用post方法將資源定義提交給apiserver；pod資源就是對應群組中的某個版本下某個名稱空間下的某個pod資源；

　　apiserver資源組織邏輯

　　提示：客戶端訪問apiserver，對應資源類似上圖中的組織方式；比如訪問default名稱空間下某個pod，其路徑就為/apis/core/v1/namespace/default/pod/mypod；對應resource包含名稱空間以及對應資源型別；

　　k8s原生apiserver組成

　　k8s原生apiserver主要有兩個元件組成，第一個元件aggregator，其功能類似web代理伺服器，第二個元件就是真正的apiserver；其工作邏輯是，使用者請求首先送達給aggregator，由aggregator根據使用者請求的資源，將對應請求路由至apiserver；簡單講aggregator這個元件主要作用就是用來路由使用者請求；預設情況aggregator會把所有請求都路由至原生的apiserver上進行響應；如果我們需要自定義apiserver，就需要在預設的aggregator上使用apiservice資源將自定義apiserver註冊到原生的apiserver上，讓其使用者請求能夠被路由至自定義apiserver進行響應；如下圖

　　提示：apiserver是k8s的唯一訪問入口，預設客戶端的所有操作都是傳送給apiserver進行響應，我們自定義的apiserver要想能夠被客戶端訪問，就必須通過內建apiserver中的aggregator元件中的路由資訊，把對應路徑的訪問路由至對應apiserver進行訪問；對應aggregator中的路由資訊，由k8s內建apiservice資源定義；簡單講apiservice資源就是用來定義原生apiserver中aggregator元件上的路由資訊；該路由就是將某某端點的訪問路由至對應apiserver；

　　檢視原生apiserver中的群組/版本資訊

[root@master01 ~]# kubectl api-versions
admissionregistration.k8s.io/v1
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
crd.projectcalico.org/v1
discovery.k8s.io/v1beta1
events.k8s.io/v1
events.k8s.io/v1beta1
extensions/v1beta1
flowcontrol.apiserver.k8s.io/v1beta1
mongodb.com/v1
networking.k8s.io/v1
networking.k8s.io/v1beta1
node.k8s.io/v1
node.k8s.io/v1beta1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1
scheduling.k8s.io/v1beta1
stable.example.com/v1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1
[root@master01 ~]#

　　提示：只有上面列出的群組版本才能夠被客戶端訪問，即客戶端只能訪問上述列表中群組版本中的資源，沒有出現群組版本是一定不會被客戶端訪問到；

　　apiservice資源的使用

　　示例：建立apiservice資源

[root@master01 ~]# cat apiservice-demo.yaml
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
  name: v2beta1.auth.ilinux.io
spec:
  insecureSkipTLSVerify: true
  group: auth.ilinux.io
  groupPriorityMinimum: 1000
  versionPriority: 15
  service:
    name: auth-api
    namespace: default
  version: v2beta1
[root@master01 ~]#

　　提示：apiservice資源屬於apiregistration.k8s.io/v1群組，其型別為APIService，其中spec.insecureSkipTLSVerify欄位用來描述是否忽略安全驗證，即不驗證https證書；true表示不驗證，false表示要驗證；group欄位用來描述對應自定義apiserver的群組；groupPriorityMinimum欄位用來描述對應群組的優先順序；versionPriority欄位用來描述對應群組版本的優先順序；service欄位是用來描述把對應群組版本的請求路由至某個service；該service就是對應自定義apiserver關聯的service；version欄位用來描述對應apiserver屬於對應群組中的某個版本；上述資源清單表示在aggregator上註冊auth.ilinux.io/v2beta1這個端點，該端點對應的後端apiserver的service是default名稱空間下的auth-api service；即客戶端訪問auth.ilinux.io/v2beta1下的資源都會被路由至default名稱空間下的auth-api service進行響應；

　　應用清單

[root@master01 ~]# kubectl apply -f apiservice-demo.yaml
apiservice.apiregistration.k8s.io/v2beta1.auth.ilinux.io created
[root@master01 ~]# kubectl get apiservice |grep auth.ilinux.io
v2beta1.auth.ilinux.io                 default/auth-api   False (ServiceNotFound)   16s
[root@master01 ~]# kubectl api-versions |grep auth.ilinux.io
auth.ilinux.io/v2beta1
[root@master01 ~]#

　　提示：可以看到應用清單以後，對應的端點資訊就出現在api-versions中；

　　上述清單只是用來說明對應apiservice資源的使用；其實應用上述清單建立apiservice資源沒有實質的作用，其原因是我們對應名稱空間下並沒有對應的服務，也沒有對應自定義apiserver；所以通常自定義apiserver，我們會用到apiservice資源來把自定義apiserver整合進原生apiserver中；接下來我們部署一個真正意義上的自定義apiserver

　　部署metrics-server

　　metrics-server是用來擴充套件k8s的第三方apiserver，其主要作用是收集pod或node上的cpu，記憶體，磁碟等指標資料，並提供一個api介面供kubectl top命令訪問；預設情況kubectl top 命令是沒法正常使用，其原因是預設apiserver上沒有對應的介面提供收集pod或node的cpu，記憶體，磁碟等核心指標資料；kubectl top命令主要用來顯示pod/node資源的cpu，記憶體，磁碟的佔用比例；該命令能夠正常使用必須依賴Metrics API；

　　預設沒有部署metrics server使用kubectl top pod/node檢視pod或節點的cpu，記憶體佔用比例

[root@master01 ~]# kubectl top
Display Resource (CPU/Memory/Storage) usage.

 The top command allows you to see the resource consumption for nodes or pods.

 This command requires Metrics Server to be correctly configured and working on the server.

Available Commands:
  node        Display Resource (CPU/Memory/Storage) usage of nodes
  pod         Display Resource (CPU/Memory/Storage) usage of pods

Usage:
  kubectl top [flags] [options]

Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
[root@master01 ~]# kubectl top pod
error: Metrics API not available
[root@master01 ~]# kubectl top node
error: Metrics API not available
[root@master01 ~]#

　　提示：預設沒有部署metrics server，使用kubectl top pod/node命令，它會告訴我們沒有可用的metrics api；

　　部署metrics server

　　下載部署清單

[root@master01 ~]# mkdir metrics-server
[root@master01 ~]# cd metrics-server
[root@master01 metrics-server]# wget https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.4.0/components.yaml
--2021-01-14 23:54:30--  https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.4.0/components.yaml
Resolving github.com (github.com)... 52.74.223.119
Connecting to github.com (github.com)|52.74.223.119|:443... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://github-production-release-asset-2e65be.s3.amazonaws.com/92132038/c700f080-1f7e-11eb-9e30-864a63f442f4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20210114%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20210114T155432Z&X-Amz-Expires=300&X-Amz-Signature=fc5a6f41ca50ec22e87074a778d2cb35e716ae6c3231afad17dfaf8a02203e35&X-Amz-SignedHeaders=host&actor_id=0&key_id=0&repo_id=92132038&response-content-disposition=attachment%3B%20filename%3Dcomponents.yaml&response-content-type=application%2Foctet-stream [following]
--2021-01-14 23:54:32--  https://github-production-release-asset-2e65be.s3.amazonaws.com/92132038/c700f080-1f7e-11eb-9e30-864a63f442f4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20210114%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20210114T155432Z&X-Amz-Expires=300&X-Amz-Signature=fc5a6f41ca50ec22e87074a778d2cb35e716ae6c3231afad17dfaf8a02203e35&X-Amz-SignedHeaders=host&actor_id=0&key_id=0&repo_id=92132038&response-content-disposition=attachment%3B%20filename%3Dcomponents.yaml&response-content-type=application%2Foctet-stream
Resolving github-production-release-asset-2e65be.s3.amazonaws.com (github-production-release-asset-2e65be.s3.amazonaws.com)... 52.217.39.44
Connecting to github-production-release-asset-2e65be.s3.amazonaws.com (github-production-release-asset-2e65be.s3.amazonaws.com)|52.217.39.44|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3962 (3.9K) [application/octet-stream]
Saving to: ‘components.yaml’

100%[===========================================================================================>] 3,962       11.0KB/s   in 0.4s   

2021-01-14 23:54:35 (11.0 KB/s) - ‘components.yaml’ saved [3962/3962]

[root@master01 metrics-server]# ls
components.yaml
[root@master01 metrics-server]#

　　修改部署清單內容

[root@master01 metrics-server]# cat components.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
    rbac.authorization.k8s.io/aggregate-to-admin: "true"
    rbac.authorization.k8s.io/aggregate-to-edit: "true"
    rbac.authorization.k8s.io/aggregate-to-view: "true"
  name: system:aggregated-metrics-reader
rules:
- apiGroups:
  - metrics.k8s.io
  resources:
  - pods
  - nodes
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  - nodes/stats
  - namespaces
  - configmaps
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server-auth-reader
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: extension-apiserver-authentication-reader
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server:system:auth-delegator
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: metrics-server
  name: system:metrics-server
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:metrics-server
subjects:
- kind: ServiceAccount
  name: metrics-server
  namespace: kube-system
---
apiVersion: v1
kind: Service
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  ports:
  - name: https
    port: 443
    protocol: TCP
    targetPort: https
  selector:
    k8s-app: metrics-server
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    k8s-app: metrics-server
  name: metrics-server
  namespace: kube-system
spec:
  selector:
    matchLabels:
      k8s-app: metrics-server
  strategy:
    rollingUpdate:
      maxUnavailable: 0
  template:
    metadata:
      labels:
        k8s-app: metrics-server
    spec:
      containers:
      - args:
        - --cert-dir=/tmp
        - --secure-port=4443
        - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
        - --kubelet-use-node-status-port
        - --kubelet-insecure-tls
        image: k8s.gcr.io/metrics-server/metrics-server:v0.4.0
        imagePullPolicy: IfNotPresent
        livenessProbe:
          failureThreshold: 3
          httpGet:
            path: /livez
            port: https
            scheme: HTTPS
          periodSeconds: 10
        name: metrics-server
        ports:
        - containerPort: 4443
          name: https
          protocol: TCP
        readinessProbe:
          failureThreshold: 3
          httpGet:
            path: /readyz
            port: https
            scheme: HTTPS
          periodSeconds: 10
        securityContext:
          readOnlyRootFilesystem: true
          runAsNonRoot: true
          runAsUser: 1000
        volumeMounts:
        - mountPath: /tmp
          name: tmp-dir
      nodeSelector:
        kubernetes.io/os: linux
      priorityClassName: system-cluster-critical
      serviceAccountName: metrics-server
      volumes:
      - emptyDir: {}
        name: tmp-dir
---
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
  labels:
    k8s-app: metrics-server
  name: v1beta1.metrics.k8s.io
spec:
  group: metrics.k8s.io
  groupPriorityMinimum: 100
  insecureSkipTLSVerify: true
  service:
    name: metrics-server
    namespace: kube-system
  version: v1beta1
  versionPriority: 100
[root@master01 metrics-server]#

　　提示：在deploy中，spec.template.containers.args欄位中加上--kubelet-insecure-tls選項，表示不驗證客戶端證書；上述清單主要用deploy控制器將metrics server執行為一個pod，然後授權metrics-server使用者能夠對pod/node資源進行只讀許可權；然後把metrics.k8s.io/v1beta1註冊到原生apiserver上，讓其客戶端訪問metrics.k8s.io下的資源能夠被路由至metrics-server這個服務上進行響應；

　　應用資源清單

[root@master01 metrics-server]# kubectl apply -f components.yaml
serviceaccount/metrics-server created
clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created
clusterrole.rbac.authorization.k8s.io/system:metrics-server created
rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created
clusterrolebinding.rbac.authorization.k8s.io/metrics-server:system:auth-delegator created
clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server created
service/metrics-server created
deployment.apps/metrics-server created
apiservice.apiregistration.k8s.io/v1beta1.metrics.k8s.io created
[root@master01 metrics-server]#

　　驗證：檢視原生apiserver是否有metrics.k8s.io/v1beta1?

[root@master01 metrics-server]# kubectl api-versions|grep metrics
metrics.k8s.io/v1beta1
[root@master01 metrics-server]#

　　提示：可以看到metrics.k8s.io/v1beta1群組已經註冊到原生apiserver上；

　　檢視metrics server pod是否執行正常？

[root@master01 metrics-server]# kubectl get pods -n kube-system
NAME                                       READY   STATUS    RESTARTS   AGE
calico-kube-controllers-744cfdf676-kh6rm   1/1     Running   4          5d7h
canal-5bt88                                2/2     Running   20         11d
canal-9ldhl                                2/2     Running   22         11d
canal-fvts7                                2/2     Running   20         11d
canal-mwtg4                                2/2     Running   23         11d
canal-rt8nn                                2/2     Running   21         11d
coredns-7f89b7bc75-k9gdt                   1/1     Running   32         37d
coredns-7f89b7bc75-kp855                   1/1     Running   31         37d
etcd-master01.k8s.org                      1/1     Running   36         37d
kube-apiserver-master01.k8s.org            1/1     Running   14         13d
kube-controller-manager-master01.k8s.org   1/1     Running   43         37d
kube-flannel-ds-fnd2w                      1/1     Running   5          5d5h
kube-flannel-ds-k9l4k                      1/1     Running   7          5d5h
kube-flannel-ds-s7w2j                      1/1     Running   4          5d5h
kube-flannel-ds-vm4mr                      1/1     Running   6          5d5h
kube-flannel-ds-zgq92                      1/1     Running   37         37d
kube-proxy-74fxn                           1/1     Running   10         10d
kube-proxy-fbl6c                           1/1     Running   8          10d
kube-proxy-n82sf                           1/1     Running   10         10d
kube-proxy-ndww5                           1/1     Running   11         10d
kube-proxy-v8dhk                           1/1     Running   11         10d
kube-scheduler-master01.k8s.org            1/1     Running   39         37d
metrics-server-58fcfcc9d-drbw2             1/1     Running   0          32s
[root@master01 metrics-server]#

　　提示：可以看到對應pod已經正常執行；

　　檢視pod裡的日誌是否正常？

[root@master01 metrics-server]# kubectl logs metrics-server-58fcfcc9d-drbw2 -n kube-system
I0114 17:52:03.601493       1 serving.go:325] Generated self-signed cert (/tmp/apiserver.crt, /tmp/apiserver.key)
E0114 17:52:04.140587       1 pathrecorder.go:107] registered "/metrics" from goroutine 1 [running]:
runtime/debug.Stack(0x1942e80, 0xc00069aed0, 0x1bb58b5)
        /usr/local/go/src/runtime/debug/stack.go:24 +0x9d
k8s.io/apiserver/pkg/server/mux.(*PathRecorderMux).trackCallers(0xc00028afc0, 0x1bb58b5, 0x8)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/mux/pathrecorder.go:109 +0x86
k8s.io/apiserver/pkg/server/mux.(*PathRecorderMux).Handle(0xc00028afc0, 0x1bb58b5, 0x8, 0x1e96f00, 0xc0006d88d0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/mux/pathrecorder.go:173 +0x84
k8s.io/apiserver/pkg/server/routes.MetricsWithReset.Install(0xc00028afc0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/routes/metrics.go:43 +0x5d
k8s.io/apiserver/pkg/server.installAPI(0xc00000a1e0, 0xc000589b00)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/config.go:711 +0x6c
k8s.io/apiserver/pkg/server.completedConfig.New(0xc000589b00, 0x1f099c0, 0xc0001449b0, 0x1bbdb5a, 0xe, 0x1ef29e0, 0x2cef248, 0x0, 0x0, 0x0)
        /go/pkg/mod/k8s.io/apiserver@v0.19.2/pkg/server/config.go:657 +0xb45
sigs.k8s.io/metrics-server/pkg/server.Config.Complete(0xc000589b00, 0xc000599440, 0xc000599b00, 0xdf8475800, 0xc92a69c00, 0x0, 0x0, 0xdf8475800)
        /go/src/sigs.k8s.io/metrics-server/pkg/server/config.go:52 +0x312
sigs.k8s.io/metrics-server/cmd/metrics-server/app.runCommand(0xc00001c6e0, 0xc000114600, 0x0, 0x0)
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/app/start.go:66 +0x157
sigs.k8s.io/metrics-server/cmd/metrics-server/app.NewMetricsServerCommand.func1(0xc0000d9340, 0xc0005a4cd0, 0x0, 0x5, 0x0, 0x0)
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/app/start.go:37 +0x33
github.com/spf13/cobra.(*Command).execute(0xc0000d9340, 0xc00013a130, 0x5, 0x5, 0xc0000d9340, 0xc00013a130)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:842 +0x453
github.com/spf13/cobra.(*Command).ExecuteC(0xc0000d9340, 0xc00013a180, 0x0, 0x0)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:950 +0x349
github.com/spf13/cobra.(*Command).Execute(...)
        /go/pkg/mod/github.com/spf13/cobra@v1.0.0/command.go:887
main.main()
        /go/src/sigs.k8s.io/metrics-server/cmd/metrics-server/metrics-server.go:38 +0xae
I0114 17:52:04.266492       1 requestheader_controller.go:169] Starting RequestHeaderAuthRequestController
I0114 17:52:04.267021       1 shared_informer.go:240] Waiting for caches to sync for RequestHeaderAuthRequestController
I0114 17:52:04.266641       1 secure_serving.go:197] Serving securely on [::]:4443
I0114 17:52:04.266670       1 tlsconfig.go:240] Starting DynamicServingCertificateController
I0114 17:52:04.266682       1 dynamic_serving_content.go:130] Starting serving-cert::/tmp/apiserver.crt::/tmp/apiserver.key
I0114 17:52:04.266688       1 configmap_cafile_content.go:202] Starting client-ca::kube-system::extension-apiserver-authentication::client-ca-file
I0114 17:52:04.267120       1 shared_informer.go:240] Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::client-ca-file
I0114 17:52:04.266692       1 configmap_cafile_content.go:202] Starting client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file
I0114 17:52:04.267301       1 shared_informer.go:240] Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file
I0114 17:52:04.367448       1 shared_informer.go:247] Caches are synced for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file 
I0114 17:52:04.367472       1 shared_informer.go:247] Caches are synced for client-ca::kube-system::extension-apiserver-authentication::client-ca-file 
I0114 17:52:04.367462       1 shared_informer.go:247] Caches are synced for RequestHeaderAuthRequestController 
[root@master01 metrics-server]#

　　提示：只要metrics server pod沒有出現錯誤日誌，或者無法註冊等資訊，就表示pod裡的容器執行正常；

　　驗證：使用kubectl top 命令檢視pod的cpu ，記憶體佔比，看看對應命令是否可以正常執行？

[root@master01 metrics-server]# kubectl top node
NAME               CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
master01.k8s.org   235m         11%    1216Mi          70%       
node01.k8s.org     140m         3%     747Mi           20%       
node02.k8s.org     120m         3%     625Mi           17%       
node03.k8s.org     133m         3%     594Mi           16%       
node04.k8s.org     125m         3%     700Mi           19%       
[root@master01 metrics-server]# kubectl top pods -n kube-system
NAME                                       CPU(cores)   MEMORY(bytes)   
calico-kube-controllers-744cfdf676-kh6rm   2m           23Mi            
canal-5bt88                                50m          118Mi           
canal-9ldhl                                22m          86Mi            
canal-fvts7                                49m          106Mi           
canal-mwtg4                                57m          113Mi           
canal-rt8nn                                56m          113Mi           
coredns-7f89b7bc75-k9gdt                   3m           12Mi            
coredns-7f89b7bc75-kp855                   3m           15Mi            
etcd-master01.k8s.org                      25m          72Mi            
kube-apiserver-master01.k8s.org            99m          410Mi           
kube-controller-manager-master01.k8s.org   14m          88Mi            
kube-flannel-ds-fnd2w                      3m           45Mi            
kube-flannel-ds-k9l4k                      3m           27Mi            
kube-flannel-ds-s7w2j                      4m           46Mi            
kube-flannel-ds-vm4mr                      3m           45Mi            
kube-flannel-ds-zgq92                      2m           19Mi            
kube-proxy-74fxn                           1m           27Mi            
kube-proxy-fbl6c                           1m           23Mi            
kube-proxy-n82sf                           1m           25Mi            
kube-proxy-ndww5                           1m           25Mi            
kube-proxy-v8dhk                           2m           23Mi            
kube-scheduler-master01.k8s.org            3m           33Mi            
metrics-server-58fcfcc9d-drbw2             6m           23Mi            
[root@master01 metrics-server]#

　　提示：可以看到kubectl top命令可以正常執行，說明metrics server 部署成功沒有問題；

　　以上就是使用apiservice資源結合自定義apiserver擴充套件k8s功能的示例，簡單總結apiservice資源的主要作用就是在aggregator上建立對應的路由資訊，該路由資訊的主要作用是將對應端點訪問路由至自定義apiserver所對應的service進行響應；

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