使用kubectl管理Kubernetes(k8s)集群：常用命令，查看負載，命名空間namespace管理

2022 年 9 月 14 日
筆記
Docker容器, Kubernetes(k8s)管理

一.系統環境
二.前言
三.kubectl
- 3.1 kubectl語法
- 3.2 kubectl格式化輸出
四.kubectl常用命令
五.查看kubernetes集群node節點和pod負載
六.命名空間namespace的管理

一.系統環境

伺服器版本	docker軟體版本	CPU架構
CentOS Linux release 7.4.1708 (Core)	Docker version 20.10.12	x86_64

二.前言

kubectl是Kubernetes提供的命令行工具，kubectl 使用 Kubernetes API 與 Kubernetes 集群的控制面進行通訊。

針對配置資訊，kubectl 在 $HOME/.kube 目錄中查找一個名為 config 的配置文件來連接Kubernetes 集群。你可以通過設置 KUBECONFIG 環境變數或設置 –kubeconfig 參數來指定其它 kubeconfig 文件。

使用kubectl命令行工具的前提是已經有一套可以正常運行的Kubernetes集群，關於Kubernetes(k8s)集群的安裝部署，可以查看部落格《Centos7 安裝部署Kubernetes(k8s)集群》//www.cnblogs.com/renshengdezheli/p/16686769.html

三.kubectl

3.1 kubectl語法

kubectl的語法為：kubectl [command] [TYPE] [NAME] [flags]，其中 command、TYPE、NAME 和 flags 分別是：

command：指定要對一個或多個資源執行的操作，例如 create、get、describe、delete。
TYPE：指定資源類型。資源類型不區分大小寫，可以指定單數、複數或縮寫形式。例如，以下命令輸出相同的結果：
```
kubectl get pod pod1
kubectl get pods pod1
kubectl get po pod1
```
NAME：指定資源的名稱。名稱區分大小寫。如果省略名稱，則顯示所有資源的詳細資訊。例如：kubectl get pods。
flags：指定可選的參數。例如，可以使用 -s 或 –server 參數指定 Kubernetes API 伺服器的地址和埠。

要對所有類型相同的資源進行分組，請執行以下操作：TYPE1 name1 name2 name<#>。
例子：kubectl get pod example-pod1 example-pod2

分別指定多個資源類型：TYPE1/name1 TYPE1/name2 TYPE2/name3 TYPE<#>/name<#>。
例子：kubectl get pod/example-pod1 replicationcontroller/example-rc1

3.2 kubectl格式化輸出

kubectl格式化輸出語法：kubectl [command] [TYPE] [NAME] -o <output_format>

輸出格式	描述
-o custom-columns=spec	使用逗號分隔的自定義列列表列印表。
-o custom-columns-file=filename	使用 filename文件中的自定義列模板列印表。
-o json	輸出 JSON 格式的 API 對象
-o jsonpath=template	列印 jsonpath 表達式定義的欄位
-o jsonpath-file=filename	列印 filename>文件中 jsonpath 表達式定義的欄位。
-o name	僅列印資源名稱而不列印任何其他內容。
-o wide	以純文本格式輸出，包含所有附加資訊。對於 Pod 包含節點名。
-o yaml	輸出 YAML 格式的 API 對象。

四.kubectl常用命令

查看從什麼地址能訪問k8s API，會顯示k8s集群的master節點的地址

[root@k8scloude1 ~]# kubectl cluster-info 
Kubernetes control plane is running at //192.168.110.130:6443
CoreDNS is running at //192.168.110.130:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

查看kubectl版本

[root@k8scloude1 ~]# kubectl version 
Client Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.0", GitCommit:"cb303e613a121a29364f75cc67d3d580833a7479", GitTreeState:"clean", BuildDate:"2021-04-08T16:31:21Z", GoVersion:"go1.16.1", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.0", GitCommit:"cb303e613a121a29364f75cc67d3d580833a7479", GitTreeState:"clean", BuildDate:"2021-04-08T16:25:06Z", GoVersion:"go1.16.1", Compiler:"gc", Platform:"linux/amd64"}

[root@k8scloude1 ~]# kubectl version --short
Client Version: v1.21.0
Server Version: v1.21.0

查看k8s的pod網段，可以看到pod網段為10.244.0.0/16

#查看初始化時候的k8s集群配置:kubeadm config view
[root@k8scloude1 ~]# kubeadm config view
Command "view" is deprecated, This command is deprecated and will be removed in a future release, please use 'kubectl get cm -o yaml -n kube-system kubeadm-config' to get the kubeadm config directly.
apiServer:
  extraArgs:
    authorization-mode: Node,RBAC
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.21.0
networking:
  dnsDomain: cluster.local
  podSubnet: 10.244.0.0/16
  serviceSubnet: 10.96.0.0/12
scheduler: {}

查看kubeconfig文件的結構

[root@k8scloude1 ~]# kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: //192.168.110.130:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: kubernetes-admin@kubernetes
current-context: kubernetes-admin@kubernetes
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: REDACTED
    client-key-data: REDACTED

五.查看kubernetes集群node節點和pod負載

5.1 安裝metric-server

查看node節點和pod的負載，發現看不了node和pod的負載，是因為沒有安裝metric-server

[root@k8scloude1 ~]# kubectl top nodes
W0109 16:45:38.197980   75467 top_node.go:119] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag
error: Metrics API not available

[root@k8scloude1 ~]# kubectl top pods
W0109 16:45:58.436117   75718 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag
error: Metrics API not available

為了查看節點和pod的負載，下面開始安裝metric-server

創建目錄，用來存放metric-server

[root@k8scloude1 ~]# mkdir metric-server

[root@k8scloude1 ~]# cd metric-server/

下載metrics-server並解壓

[root@k8scloude1 metric-server]# wget //github.com/kubernetes-sigs/metrics-server/archive/v0.3.6.tar.gz

[root@k8scloude1 metric-server]# ls
v0.3.6.tar.gz

[root@k8scloude1 metric-server]# tar xf v0.3.6.tar.gz 

[root@k8scloude1 metric-server]# ls
metrics-server-0.3.6  v0.3.6.tar.gz

[root@k8scloude1 metric-server]# cd metrics-server-0.3.6/

[root@k8scloude1 metrics-server-0.3.6]# ls
cmd  code-of-conduct.md  CONTRIBUTING.md  deploy  Gopkg.lock  Gopkg.toml  hack  LICENSE  Makefile  OWNERS  OWNERS_ALIASES  pkg  README.md  SECURITY_CONTACTS  vendor  version

[root@k8scloude1 metrics-server-0.3.6]# cd deploy/

[root@k8scloude1 deploy]# ls
1.7  1.8+  docker  minikube

[root@k8scloude1 deploy]# cd 1.8+

[root@k8scloude1 1.8+]# ls
aggregated-metrics-reader.yaml  auth-delegator.yaml  auth-reader.yaml  metrics-apiservice.yaml  metrics-server-deployment.yaml  metrics-server-service.yaml  resource-reader.yaml

查看需要下載的鏡像，image: k8s.gcr.io/metrics-server-amd64:v0.3.6這個鏡像中國訪問不了，我們手動下載一個中國鏡像

[root@k8scloude1 1.8+]# grep image metrics-server-deployment.yaml
      # mount in tmp so we can safely use from-scratch images and/or read-only containers
        image: k8s.gcr.io/metrics-server-amd64:v0.3.6
        imagePullPolicy: Always

在k8s集群master節點和worker節點都需要下載metrics-server-amd64:v0.3.6鏡像

[root@k8scloude1 1.8+]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6

[root@k8scloude1 1.8+]# docker images | grep mirrorgooglecontainers
REPOSITORY                                                        TAG        IMAGE ID       CREATED         SIZE
mirrorgooglecontainers/metrics-server-amd64                       v0.3.6     9dd718864ce6   2 years ago     39.9MB

鏡像已經下好了，現在進行docker tag重命名，並刪除原鏡像mirrorgooglecontainers/metrics-server-amd64:v0.3.6

[root@k8scloude1 1.8+]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6

[root@k8scloude1 1.8+]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6

worker節點也進行相同操作

[root@k8scloude2 ~]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6

[root@k8scloude2 ~]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6

[root@k8scloude2 ~]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6

[root@k8scloude3 ~]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6

[root@k8scloude3 ~]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6

[root@k8scloude3 ~]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6

修改配置文件，鏡像下載策略imagePullPolicy改為IfNotPresent，IfNotPresent表示只有當鏡像在本地不存在時才會拉取

[root@k8scloude1 1.8+]# pwd
/root/metric-server/metrics-server-0.3.6/deploy/1.8+

#修改內容如下： imagePullPolicy: IfNotPresent
#        command:
#      - /metrics-server
#        - --metric-resolution=30s
#        - --kubelet-insecure-tls
#        - --kubelet-preferred-address-types=InternalIP
[root@k8scloude1 1.8+]# tail -20 metrics-server-deployment.yaml
        k8s-app: metrics-server
    spec:
      serviceAccountName: metrics-server
      volumes:
      # mount in tmp so we can safely use from-scratch images and/or read-only containers
      - name: tmp-dir
        emptyDir: {}
      containers:
      - name: metrics-server
        image: k8s.gcr.io/metrics-server-amd64:v0.3.6
        imagePullPolicy: IfNotPresent
        command:
        - /metrics-server
        - --metric-resolution=30s
        - --kubelet-insecure-tls
        - --kubelet-preferred-address-types=InternalIP
        volumeMounts:
        - name: tmp-dir
          mountPath: /tmp

安裝metrics-server

#kubectl apply -f .    .表示安裝當前目錄下的所有文件
[root@k8scloude1 1.8+]# kubectl apply -f .
clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleBinding
clusterrolebinding.rbac.authorization.k8s.io/metrics-server:system:auth-delegator created
Warning: rbac.authorization.k8s.io/v1beta1 RoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 RoleBinding
rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created
Warning: apiregistration.k8s.io/v1beta1 APIService is deprecated in v1.19+, unavailable in v1.22+; use apiregistration.k8s.io/v1 APIService
apiservice.apiregistration.k8s.io/v1beta1.metrics.k8s.io created
serviceaccount/metrics-server created
deployment.apps/metrics-server created
service/metrics-server created
clusterrole.rbac.authorization.k8s.io/system:metrics-server created
clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server created

查看所有的命名空間

[root@k8scloude1 1.8+]# kubectl get ns
NAME              STATUS   AGE
default           Active   18h
kube-node-lease   Active   18h
kube-public       Active   18h
kube-system       Active   18h

當觀察到metrics-server-bcfb98c76-k5dmj狀態為Running，metrics-server服務就正常啟動了

[root@k8scloude1 1.8+]# kubectl get pod -n kube-system -o wide
NAME                                       READY   STATUS    RESTARTS   AGE   IP                NODE         NOMINATED NODE   READINESS GATES
calico-kube-controllers-6b9fbfff44-4jzkj   1/1     Running   2          19h   10.244.251.194    k8scloude3   <none>           <none>
calico-node-bdlgm                          1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
calico-node-hx8bk                          1/1     Running   1          19h   192.168.110.128   k8scloude3   <none>           <none>
calico-node-nsbfs                          1/1     Running   1          19h   192.168.110.129   k8scloude2   <none>           <none>
coredns-545d6fc579-7wm95                   1/1     Running   1          19h   10.244.158.68     k8scloude1   <none>           <none>
coredns-545d6fc579-87q8j                   1/1     Running   1          19h   10.244.158.67     k8scloude1   <none>           <none>
etcd-k8scloude1                            1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
kube-apiserver-k8scloude1                  1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
kube-controller-manager-k8scloude1         1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
kube-proxy-599xh                           1/1     Running   1          19h   192.168.110.128   k8scloude3   <none>           <none>
kube-proxy-lpj8z                           1/1     Running   1          19h   192.168.110.129   k8scloude2   <none>           <none>
kube-proxy-zxlk9                           1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
kube-scheduler-k8scloude1                  1/1     Running   1          19h   192.168.110.130   k8scloude1   <none>           <none>
metrics-server-bcfb98c76-k5dmj             1/1     Running   0          70s   10.244.112.131    k8scloude2   <none>           <none>

5.2 查看node負載

查看node的負載

[root@k8scloude1 1.8+]# kubectl top node 
W0110 11:37:47.025099   75026 top_node.go:119] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag
NAME         CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
k8scloude1   257m         12%    1487Mi          45%       
k8scloude2   104m         5%     698Mi           36%       
k8scloude3   102m         5%     701Mi           36%

5.3 查看pod負載

查看pod的負載

注釋：一核心分成1000個微核心m 1核=1000m

[root@k8scloude1 1.8+]# kubectl top pods
W0110 11:38:40.576780   75696 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag
No resources found in default namespace.

#-A表示所有命名空間
[root@k8scloude1 1.8+]# kubectl top pods -A
W0110 11:38:47.276962   75784 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag
NAMESPACE     NAME                                       CPU(cores)   MEMORY(bytes)   
kube-system   calico-kube-controllers-6b9fbfff44-4jzkj   2m           25Mi            
kube-system   calico-node-bdlgm                          37m          170Mi           
kube-system   calico-node-hx8bk                          43m          157Mi           
kube-system   calico-node-nsbfs                          56m          164Mi           
kube-system   coredns-545d6fc579-7wm95                   3m           18Mi            
kube-system   coredns-545d6fc579-87q8j                   3m           18Mi            
kube-system   etcd-k8scloude1                            14m          91Mi            
kube-system   kube-apiserver-k8scloude1                  60m          351Mi           
kube-system   kube-controller-manager-k8scloude1         21m          56Mi            
kube-system   kube-proxy-599xh                           1m           24Mi            
kube-system   kube-proxy-lpj8z                           1m           24Mi            
kube-system   kube-proxy-zxlk9                           1m           24Mi            
kube-system   kube-scheduler-k8scloude1                  3m           23Mi            
kube-system   metrics-server-bcfb98c76-k5dmj             1m           13Mi

六.命名空間namespace的管理

6.1 何為命名空間namespace

在 Kubernetes 中，命名空間（Namespace）提供一種機制，將同一集群中的資源劃分為相互隔離的組。同一命名空間內的資源名稱要唯一，但跨命名空間時沒有這個要求。命名空間作用域僅針對帶有命名空間的對象，例如 Deployment、Service 等，這種作用域對集群訪問的對象不適用，例如 StorageClass、Node、PersistentVolume 等。

6.2 管理命名空間namespace

查看所有的命名空間

[root@k8scloude1 1.8+]# kubectl get namespaces 
NAME              STATUS   AGE
default           Active   19h
kube-node-lease   Active   19h
kube-public       Active   19h
kube-system       Active   19h

[root@k8scloude1 1.8+]# kubectl get ns
NAME              STATUS   AGE
default           Active   19h
kube-node-lease   Active   19h
kube-public       Active   19h
kube-system       Active   19h

創建命名空間，注意：不同的namespace之間相互隔離

[root@k8scloude1 1.8+]# kubectl create ns ns1
namespace/ns1 created

[root@k8scloude1 1.8+]# kubectl create ns ns2
namespace/ns2 created

[root@k8scloude1 1.8+]# kubectl get ns
NAME              STATUS   AGE
default           Active   19h
kube-node-lease   Active   19h
kube-public       Active   19h
kube-system       Active   19h
ns1               Active   6s
ns2               Active   4s

獲取全局上下文，可以看到當前命名空間為default

[root@k8scloude1 ~]# kubectl config get-contexts 
CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE
*         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   default

切換命名空間

#切換命名空間
[root@k8scloude1 ~]# kubectl config set-context --current --namespace=kube-system
Context "kubernetes-admin@kubernetes" modified.

[root@k8scloude1 ~]# kubectl config get-contexts 
CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE
*         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   kube-system

#獲取當前K8S上下文
[root@k8scloude1 ~]# kubectl config current-context 
kubernetes-admin@kubernetes

6.2 使用kubens管理命名空間namespace

默認的切換命名空間的命令不好用，可以使用第三方的命名空間切換工具：kubens，kubens命令所在的網站為：//github.com/ahmetb/kubectx/releases/

下載kubens，並授予可執行許可權

[root@k8scloude1 ~]# wget //github.com/ahmetb/kubectx/releases/download/v0.9.4/kubens

[root@k8scloude1 ~]# ll -h kubens 
-rw-r--r-- 1 root root 5.5K 12月  8 15:46 kubens

[root@k8scloude1 ~]# chmod +x kubens 

[root@k8scloude1 ~]# mv kubens /bin/

[root@k8scloude1 ~]# ls /bin/kubens 
/bin/kubens

查看所有的命名空間

[root@k8scloude1 ~]# kubens 
default
kube-node-lease
kube-public
kube-system
ns1
ns2

切換namespace

#切換namespace到kube-system
[root@k8scloude1 ~]# kubens kube-system
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "kube-system".

#此時，默認查詢的就是kube-system命名空間下的pod
[root@k8scloude1 ~]# kubectl get pods -o wide
NAME                                       READY   STATUS    RESTARTS   AGE   IP                NODE         NOMINATED NODE   READINESS GATES
calico-kube-controllers-6b9fbfff44-4jzkj   1/1     Running   2          20h   10.244.251.194    k8scloude3   <none>           <none>
calico-node-bdlgm                          1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
calico-node-hx8bk                          1/1     Running   1          20h   192.168.110.128   k8scloude3   <none>           <none>
calico-node-nsbfs                          1/1     Running   1          20h   192.168.110.129   k8scloude2   <none>           <none>
coredns-545d6fc579-7wm95                   1/1     Running   1          20h   10.244.158.68     k8scloude1   <none>           <none>
coredns-545d6fc579-87q8j                   1/1     Running   1          20h   10.244.158.67     k8scloude1   <none>           <none>
etcd-k8scloude1                            1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
kube-apiserver-k8scloude1                  1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
kube-controller-manager-k8scloude1         1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
kube-proxy-599xh                           1/1     Running   1          20h   192.168.110.128   k8scloude3   <none>           <none>
kube-proxy-lpj8z                           1/1     Running   1          20h   192.168.110.129   k8scloude2   <none>           <none>
kube-proxy-zxlk9                           1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
kube-scheduler-k8scloude1                  1/1     Running   1          20h   192.168.110.130   k8scloude1   <none>           <none>
metrics-server-bcfb98c76-k5dmj             1/1     Running   0          56m   10.244.112.131    k8scloude2   <none>           <none>

切換namespace到default

#切換namespace到default
[root@k8scloude1 ~]# kubens default
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "default".

#此時，默認查詢的就是default命名空間下的pod
[root@k8scloude1 ~]# kubectl get pods -o wide
No resources found in default namespace.

#要查詢kube-public命名空間下的pod，使用-n kube-public指定
[root@k8scloude1 ~]# kubectl get pods -n kube-public
No resources found in kube-public namespace.

Tags: Docker容器 Kubernetes(k8s)管理

使用kubectl管理Kubernetes(k8s)集群：常用命令，查看負載，命名空間namespace管理

一.系統環境

二.前言

三.kubectl

3.1 kubectl語法

3.2 kubectl格式化輸出

四.kubectl常用命令

五.查看kubernetes集群node節點和pod負載

5.1 安裝metric-server

5.2 查看node負載

5.3 查看pod負載

六.命名空間namespace的管理

6.1 何為命名空間namespace

6.2 管理命名空間namespace

6.2 使用kubens管理命名空間namespace

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使用kubectl管理Kubernetes(k8s)集群：常用命令，查看負載，命名空間namespace管理

一.系統環境

二.前言

三.kubectl

3.1 kubectl語法

3.2 kubectl格式化輸出

四.kubectl常用命令

五.查看kubernetes集群node節點和pod負載

5.1 安裝metric-server

5.2 查看node負載

5.3 查看pod負載

六.命名空間namespace的管理

6.1 何為命名空間namespace

6.2 管理命名空間namespace

6.2 使用kubens管理命名空間namespace

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