如何理解K8S中kubectl

这期内容当中小编将会给大家带来有关如何理解K8S中kubectl，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。

一、kubectl 陈述式管理方法

kubectl小洁：kubectl是官方的CLI命令行工具，用于apiserver进行通信，将用户在命令行输入的命令，组织并转化为apiserver能识别的信息，进而实现管理k8s各种资源的一种有效途径。1、查看当前集群所有命名空间[root@test-nodes1 ~]# kubectl get namespaceNAME              STATUS   AGEdefault           Active   42hkube-node-lease   Active   42hkube-public       Active   42hkube-system       Active   42h------------------------------------------------------------------------------------------2、查看default命名空间下的所有资源[root@test-nodes1 ~]# kubectl get all -n defaultNAME                  READY   STATUS             RESTARTS   AGEpod/nginx-ds-76fr8    0/1     ImagePullBackOff   0          39hpod/nginx-ds-zz7jn    0/1     ErrImagePull       0          39hpod/nginx-ds1-qg45q   1/1     Running            0          39hpod/nginx-ds1-whnmv   1/1     Running            0          39h#pod资源NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGEservice/kubernetes   ClusterIP   192.168.0.1           443/TCP   42h#service资源NAME                       DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGEdaemonset.apps/nginx-ds    2         2         0       2            0                     39hdaemonset.apps/nginx-ds1   2         2         2       2            2                     39h#pod控制器------------------------------------------------------------------------------------------3、创建与删除命名空间[root@test-nodes1 ~]# kubectl create namespace testnamespace/test created[root@test-nodes1 ~]# kubectl get namespaceNAME              STATUS   AGEdefault           Active   42hkube-node-lease   Active   42hkube-public       Active   42hkube-system       Active   42htest              Active   6s[root@test-nodes1 ~]# kubectl delete namespace testnamespace "test" deleted------------------------------------------------------------------------------------------4、创建deployment（pods控制器)资源[root@test-nodes1 ~]# kubectl create deployment nignx-dp --image=test-harbor.cedarhd.com/public/nginx:v1.7.9 -n kube-publicdeployment.apps/nignx-dp created------------------------------------------------------------------------------------------5、查看kube-public命名空间下的deployment资源控制器[root@test-nodes1 ~]# kubectl get deployment -n kube-publicNAME       READY   UP-TO-DATE   AVAILABLE   AGEnignx-test   0/1     1            0           70s------------------------------------------------------------------------------------------6、查看kube-public命名空间下pods的运行情况[root@test-nodes1 ~]# kubectl get deployment -n kube-publicNAME         READY   UP-TO-DATE   AVAILABLE   AGEnignx-test   1/1     1            1           21s------------------------------------------------------------------------------------------7、查看kube-public空间下的pods资源[root@test-nodes1 ~]# kubectl get pods -n kube-public -o wideNAME                          READY   STATUS             RESTARTS   AGE    IP           NODE                      NOMINATED NODE   READINESS GATESnignx-dp-7f6d4979bd-nnc57     0/1     ImagePullBackOff   0          13m    172.7.21.4   test-nodes1.cedarhd.com              nignx-test-655d6fbcb5-r9t57   1/1     Running            0          4m1s   172.7.22.4   test-nodes2.cedarhd.com              ------------------------------------------------------------------------------------------8、在test-nodes2.cedarhd.com节点上curl 172.7.22.4 nginx[root@test-nodes2 ~]# curl 172.7.22.4
Welcome to nginx!
If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.
For online documentation and support please refer tonginx.org.
Commercial support is available atnginx.com.
Thank you for using nginx.
------------------------------------------------------------------------------------------9、查看deployment下具体pods（nginx-test）详细信息[root@test-nodes1 ~]# kubectl describe deployment nignx-test -n kube-publicName:                   nignx-testNamespace:              kube-publicCreationTimestamp:      Mon, 03 Feb 2020 02:02:59 -0500Labels:                 app=nignx-testAnnotations:            deployment.kubernetes.io/revision: 1Selector:               app=nignx-testReplicas:               1 desired | 1 updated | 1 total | 1 available | 0 unavailableStrategyType:           RollingUpdateMinReadySeconds:        0RollingUpdateStrategy:  25% max unavailable, 25% max surgePod Template:  Labels:  app=nignx-test  Containers:   nginx:    Image:        test-harbor.cedarhd.com/public/nginx:v1.7.9    Port:             Host Port:        Environment:      Mounts:         Volumes:        Conditions:  Type           Status  Reason  ----           ------  ------  Available      True    MinimumReplicasAvailable  Progressing    True    NewReplicaSetAvailableOldReplicaSets:  NewReplicaSet:   nignx-test-655d6fbcb5 (1/1 replicas created)Events:  Type    Reason             Age   From                   Message  ----    ------             ----  ----                   -------  Normal  ScalingReplicaSet  22m   deployment-controller  Scaled up replica set nignx-test-655d6fbcb5 to 1    ------------------------------------------------------------------------------------------10、进入nginx-test pod资源[root@test-nodes1 ~]# kubectl get pods -n kube-publicNAME                          READY   STATUS             RESTARTS   AGEnignx-test-655d6fbcb5-r9t57   1/1     Running            0          24m[root@test-nodes1 ~]# kubectl exec -ti nignx-test-655d6fbcb5-r9t57 /bin/bash -n kube-public#与docker 操作方法一致root@nignx-test-655d6fbcb5-r9t57:/# ip addr1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00    inet 127.0.0.1/8 scope host lo       valid_lft forever preferred_lft forever12: eth0@if13:  mtu 1500 qdisc noqueue state UP     link/ether 02:42:ac:07:16:04 brd ff:ff:ff:ff:ff:ff    inet 172.7.22.4/24 brd 172.7.22.255 scope global eth0       valid_lft forever preferred_lft forever------------------------------------------------------------------------------------------11、删除pod资源（即重启）[root@test-nodes1 ~]# kubectl delete pod nignx-test-655d6fbcb5-r9t57 -n kube-publicpod "nignx-test-655d6fbcb5-r9t57" deleted[root@test-nodes1 ~]# kubectl get pods -n kube-public -o wideNAME                          READY   STATUS             RESTARTS   AGE   IP           NODE                      NOMINATED NODE   READINESS GATESnignx-dp-7f6d4979bd-nnc57     0/1     ImagePullBackOff   0          40m   172.7.21.4   test-nodes1.cedarhd.com              nignx-test-655d6fbcb5-c42z8   1/1     Running            0          18s   172.7.21.5   test-nodes1.cedarhd.com              ------------------------------------------------------------------------------------------12、删除deployment[root@test-nodes1 ~]# kubectl get deploy -n kube-publicNAME         READY   UP-TO-DATE   AVAILABLE   AGEnignx-dp     0/1     1            0           53mnignx-test   1/1     1            1           36m[root@test-nodes1 ~]# kubectl delete deploy nignx-dp -n kube-publicdeployment.extensions "nignx-dp" deleted------------------------------------------------------------------------------------------13、为nginx-dp pod资源创建service资源，保障pod的高可用,通过集群IP访问[root@test-nodes1 ~]# kubectl get all -n kube-publicNAME                            READY   STATUS    RESTARTS   AGEpod/nginx-dp-5b9b697bcc-jtrlp   1/1     Running   0          17sNAME                       READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/nginx-dp   1/1     1            1           17sNAME                                  DESIRED   CURRENT   READY   AGEreplicaset.apps/nginx-dp-5b9b697bcc   1         1         1       17s[root@test-nodes1 ~]# kubectl get pods -n kube-public -o wideNAME                        READY   STATUS    RESTARTS   AGE     IP           NODE                      NOMINATED NODE   READINESS GATESnginx-dp-5b9b697bcc-jtrlp   1/1     Running   0          3m19s   172.7.21.4   test-nodes1.cedarhd.com              [root@test-nodes1 ~]# kubectl expose deployment nginx-dp --port=80 -n kube-publicservice/nginx-dp exposed[root@test-nodes1 ~]# kubectl get svc -n kube-public      #查看service资源NAME       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEnginx-dp   ClusterIP   192.168.224.56           80/TCP    12m[root@test-nodes1 ~]# kubectl get all -n kube-publicNAME                            READY   STATUS    RESTARTS   AGEpod/nginx-dp-5b9b697bcc-jtrlp   1/1     Running   0          5m21sNAME               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEservice/nginx-dp   ClusterIP   192.168.224.56           80/TCP    79sNAME                       READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/nginx-dp   1/1     1            1           5m21sNAME                                  DESIRED   CURRENT   READY   AGEreplicaset.apps/nginx-dp-5b9b697bcc   1         1         1       5m21s[root@test-nodes1 ~]# curl 192.168.224.56
Welcome to nginx!
If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.
For online documentation and support please refer tonginx.org.
Commercial support is available atnginx.com.
Thank you for using nginx.
[root@test-nodes1 ~]# ipvsadm -lnIP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags  -> RemoteAddress:Port           Forward Weight ActiveConn InActConnTCP  192.168.0.1:443 nq  -> 10.3.153.221:6443            Masq    1      0          0           -> 10.3.153.222:6443            Masq    1      0          0         TCP  192.168.224.56:80 nq  -> 172.7.21.4:80                Masq    1      0          0

二、kubectl 声明式管理方法

小结：声明式资源管理方法依赖于-资源配置清单（yaml\json），偏于修改POD配置。

1、查看当前pod的资源配置清单[root@test-nodes1 ~]# kubectl get pods -n kube-publicNAME                        READY   STATUS    RESTARTS   AGEnginx-dp-5b9b697bcc-jtrlp   1/1     Running   0          5h31m-nodes1.cedarhd.com              [root@test-nodes1 ~]# kubectl get pods nginx-dp-5b9b697bcc-jtrlp -n kube-public -o yamlapiVersion: v1kind: Pod                #类型为podmetadata:  creationTimestamp: "2020-02-03T07:50:11Z"  generateName: nginx-dp-5b9b697bcc-  labels:    app: nginx-dp    pod-template-hash: 5b9b697bcc  name: nginx-dp-5b9b697bcc-jtrlp  namespace: kube-public  ownerReferences:  - apiVersion: apps/v1    blockOwnerDeletion: true    controller: true    kind: ReplicaSet    name: nginx-dp-5b9b697bcc    uid: 30bbaf90-c97e-4167-9419-45a632e9b3ce  resourceVersion: "222257"  selfLink: /api/v1/namespaces/kube-public/pods/nginx-dp-5b9b697bcc-jtrlp  uid: 59d63844-8ee7-4d7e-8536-d4e5de1ba903spec:  containers:  - image: test-harbor.cedarhd.com/public/nginx:v1.7.9    imagePullPolicy: IfNotPresent    name: nginx    resources: {}    terminationMessagePath: /dev/termination-log    terminationMessagePolicy: File    volumeMounts:    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount      name: default-token-nt4w9      readOnly: true  dnsPolicy: ClusterFirst  enableServiceLinks: true  nodeName: test-nodes1.cedarhd.com  priority: 0  restartPolicy: Always  schedulerName: default-scheduler  securityContext: {}  serviceAccount: default  serviceAccountName: default  terminationGracePeriodSeconds: 30  tolerations:  - effect: NoExecute    key: node.kubernetes.io/not-ready    operator: Exists    tolerationSeconds: 300  - effect: NoExecute    key: node.kubernetes.io/unreachable    operator: Exists    tolerationSeconds: 300  volumes:  - name: default-token-nt4w9    secret:      defaultMode: 420      secretName: default-token-nt4w9status:  conditions:  - lastProbeTime: null    lastTransitionTime: "2020-02-03T07:50:11Z"    status: "True"    type: Initialized  - lastProbeTime: null    lastTransitionTime: "2020-02-03T07:50:14Z"    status: "True"    type: Ready  - lastProbeTime: null    lastTransitionTime: "2020-02-03T07:50:14Z"    status: "True"    type: ContainersReady  - lastProbeTime: null    lastTransitionTime: "2020-02-03T07:50:11Z"    status: "True"    type: PodScheduled  containerStatuses:  - containerID: docker://745d5ad3412e5bccf2fb27dacce57e76987e8f6881cdb3aec79912888ba37ad6    image: test-harbor.cedarhd.com/public/nginx:v1.7.9    imageID: docker-pullable://test-harbor.cedarhd.com/public/nginx@sha256:b1f5935eb2e9e2ae89c0b3e2e148c19068d91ca502e857052f14db230443e4c2    lastState: {}    name: nginx    ready: true    restartCount: 0    state:      running:        startedAt: "2020-02-03T07:50:13Z"  hostIP: 10.3.153.221  phase: Running  podIP: 172.7.21.4  qosClass: BestEffort  startTime: "2020-02-03T07:50:11Z"------------------------------------------------------------------------------------------2、获取service资源的配置清单[root@test-nodes1 ~]# kubectl get service -n kube-publicNAME       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEnginx-dp   ClusterIP   192.168.224.56           80/TCP    5h31m[root@test-nodes1 ~]# kubectl get service nginx-dp -o yaml -n kube-publicapiVersion: v1kind: Service        #类型为servicemetadata:  creationTimestamp: "2020-02-03T07:54:13Z"  labels:    app: nginx-dp  name: nginx-dp  namespace: kube-public  resourceVersion: "222606"  selfLink: /api/v1/namespaces/kube-public/services/nginx-dp  uid: 1b2310b5-6016-4692-b632-5c43d6dc4de5spec:  clusterIP: 192.168.224.56  ports:  - port: 80    protocol: TCP    targetPort: 80  selector:    app: nginx-dp  sessionAffinity: None  type: ClusterIPstatus:  loadBalancer: {}    ------------------------------------------------------------------------------------------3、explain查看字段帮助说明kubectl explain service.metadata ------------------------------------------------------------------------------------------4、新建一个service的资源配置清单[root@test-nodes1 ~]# vi nginx-ds-svc.yamlapiVersion: v1kind: Servicemetadata:  labels:    app: nginx-ds  name: nginx-ds  namespace: kube-publicspec:  ports:  - port: 80    protocol: TCP    targetPort: 80  selector:    app: nginx-ds  sessionAffinity: None  type: ClusterIP------------------------------------------------------------------------------------------5、通过声明式资源配置清单创建一个service资源[root@test-nodes1 ~]# kubectl create -f nginx-ds-svc.yaml service/nginx-ds created[root@test-nodes1 ~]# kubectl get service -n kube-publicNAME       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEnginx-dp   ClusterIP   192.168.224.56           80/TCP    5h39mnginx-ds   ClusterIP   192.168.66.3             80/TCP    16s------------------------------------------------------------------------------------------6、在线修改nginx-ds的 service 资源端口为81[root@test-nodes1 ~]# kubectl get svc -n kube-publicNAME       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEnginx-dp   ClusterIP   192.168.224.56           80/TCP    5h49mnginx-ds   ClusterIP   192.168.66.3             80/TCP    10m[root@test-nodes1 ~]# kubectl edit svc nginx-ds -n kube-public# Please edit the object below. Lines beginning with a '#' will be ignored,# and an empty file will abort the edit. If an error occurs while saving this file will be# reopened with the relevant failures.#apiVersion: v1kind: Servicemetadata:  creationTimestamp: "2020-02-03T13:23:41Z"  labels:    app: nginx-ds  name: nginx-ds  namespace: kube-public  resourceVersion: "250724"  selfLink: /api/v1/namespaces/kube-public/services/nginx-ds  uid: 5840630d-e00d-4e98-91a1-2b65a1eb22f4spec:  clusterIP: 192.168.66.3  ports:  - port: 81      #修改对外端口81    protocol: TCP    targetPort: 80  selector:    app: nginx-ds  sessionAffinity: None  type: ClusterIPstatus:  loadBalancer: {}"/tmp/kubectl-edit-wp634.yaml" 27L, 684C writtenservice/nginx-ds edited[root@test-nodes1 ~]# kubectl get svc -n kube-publicNAME       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEnginx-dp   ClusterIP   192.168.224.56           80/TCP    5h50mnginx-ds   ClusterIP   192.168.66.3             81/TCP    10m------------------------------------------------------------------------------------------7、删除一个service资源[root@test-nodes1 ~]# kubectl delete svc nginx-ds -n kube-publicservice "nginx-ds" deleted

三、关于kubectl的核心资源理解

[root@test-nodes1 ~]# kubectl get all -n kube-publicNAME                            READY   STATUS    RESTARTS   AGEpod/nginx-dp-5b9b697bcc-jtrlp   1/1     Running   0          6h2m#pod资源，承载容器应用所在NAME               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEservice/nginx-dp   ClusterIP   192.168.224.56           80/TCP    5h67m#service资源，Service是Kubernetes里最核心的资源对象之一,Service定义了一个服务的访问入口地址,前端的应用(Pod)通过这个入口地址访问其背后的一组由Pod副本组成的集群实力NAME                       READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/nginx-dp   1/1     1            1           6h2m#deployment资源，Deployment同样也是Kubernetes系统的一个核心概念，主要职责和RC一样的都是保证Pod的数量和健康，可理解为pod控制器,当我们删除pod时，会再启动，不是真正删除，如需删除该pod，必须删除该控制器NAME                                  DESIRED   CURRENT   READY   AGEreplicaset.apps/nginx-dp-5b9b697bcc   1         1         1       6h2m

四、通过kubectl单独创建一个pod\deployment\service

1、创建一个nginx pod[root@test-nodes1 ~]# vi nginx-pod.yamlapiVersion: v1kind: Podmetadata:  name: nginx  labels:    app: webspec:  containers:    - name: nginx      image: test-harbor.cedarhd.com/public/nginx:v1.7.9      ports:        - containerPort: 80[root@test-nodes1 ~]# kubectl create -f nginx-pod.yaml       #创建一个PODpod/nginx created[root@test-nodes1 ~]# kubectl get allNAME                  READY   STATUS    RESTARTS   AGEpod/nginx             1/1     Running   0          10m       #刚刚创建的PODpod/nginx-ds1-qg45q   1/1     Running   0          47hpod/nginx-ds1-whnmv   1/1     Running   0          47hNAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGEservice/kubernetes   ClusterIP   192.168.0.1           443/TCP   2d2hNAME                       DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGEdaemonset.apps/nginx-ds1   2         2         2       2            2                     47h------------------------------------------------------------------------------------------2、为该pod创建一个service[root@test-nodes1 ~]# kubectl expose pod nginx --port=80 -n defaultservice/nginx exposed[root@test-nodes2 ~]# kubectl get all NAME                  READY   STATUS    RESTARTS   AGEpod/nginx             1/1     Running   0          14mpod/nginx-ds1-qg45q   1/1     Running   0          47hpod/nginx-ds1-whnmv   1/1     Running   0          47hNAME                 TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)   AGEservice/kubernetes   ClusterIP   192.168.0.1               443/TCP   2d2hservice/nginx        ClusterIP   192.168.123.163           80/TCP    107sNAME                       DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGEdaemonset.apps/nginx-ds1   2         2         2       2            2                     47h[root@test-nodes2 ~]# curl 192.168.123.163    获取nginx页面------------------------------------------------------------------------------------------3、创建一个deployment[root@test-nodes2 ~]# kubectl create deployment nginx-test --image=test-harbor.cedarhd.com/public/nginx:v1.7.9deployment.apps/nginx-test created[root@test-nodes2 ~]# kubectl get allNAME                              READY   STATUS    RESTARTS   AGEpod/nginx                         1/1     Running   0          27mpod/nginx-ds1-qg45q               1/1     Running   0          47hpod/nginx-ds1-whnmv               1/1     Running   0          47hpod/nginx-test-5674474869-5nr7j   1/1     Running   0          4sNAME                 TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)   AGEservice/kubernetes   ClusterIP   192.168.0.1               443/TCP   2d2hservice/nginx        ClusterIP   192.168.123.163           80/TCP    15mNAME                       DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGEdaemonset.apps/nginx-ds1   2         2         2       2            2                     47hNAME                         READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/nginx-test   1/1     1            1           4sNAME                                    DESIRED   CURRENT   READY   AGEreplicaset.apps/nginx-test-5674474869   1         1         1       4s

上述就是小编为大家分享的如何理解K8S中kubectl了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注行业资讯频道。