【K8S运维知识汇总】第3天2：kubectl详解——声明式资源管理方法

通过陈述式创建的pod资源，获得统一配置清单

[root@hdss7-21 ~]# kubectl get pods nginx-dp-5dfc689474-bqk8w -o yaml -n kube-public
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2020-07-01T12:19:34Z"
  generateName: nginx-dp-5dfc689474-
  labels:
    app: nginx-dp
    pod-template-hash: 5dfc689474
  name: nginx-dp-5dfc689474-bqk8w
  namespace: kube-public
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: ReplicaSet
    name: nginx-dp-5dfc689474
    uid: 109c9920-2fdc-483b-8254-eb10f3e90443
  resourceVersion: "77238"
  selfLink: /api/v1/namespaces/kube-public/pods/nginx-dp-5dfc689474-bqk8w
  uid: ba5311df-0b9c-41fb-b270-56e0604a54f1
spec:
  containers:
  - image: harbor.od.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-vx5v7
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: hdss7-21.host.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-vx5v7
    secret:
      defaultMode: 420
      secretName: default-token-vx5v7
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2020-07-01T12:19:35Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2020-07-01T12:19:36Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2020-07-01T12:19:36Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2020-07-01T12:19:35Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: docker://f5f6ea8d2bf8669efc7daf651a1404869c827a3fd2cbd6f85df8346cfd55de6d
    image: harbor.od.com/public/nginx:v1.7.9
    imageID: docker-pullable://harbor.od.com/public/nginx@sha256:b1f5935eb2e9e2ae89c0b3e2e148c19068d91ca502e857052f14db230443e4c2
    lastState: {}
    name: nginx
    ready: true
    restartCount: 0
    state:
      running:
        startedAt: "2020-07-01T12:19:35Z"
  hostIP: 10.4.7.21
  phase: Running
  podIP: 172.7.21.2
  qosClass: BestEffort
  startTime: "2020-07-01T12:19:35Z"

查看svc资源对应的配置清单

[root@hdss7-21 ~]# kubectl get svc nginx-dp -o yaml -n kube-public
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2020-07-01T04:12:24Z"
  labels:
    app: nginx-dp
  name: nginx-dp
  namespace: kube-public
  resourceVersion: "63896"
  selfLink: /api/v1/namespaces/kube-public/services/nginx-dp
  uid: b66f191e-0471-44ec-800a-f3ee6382b40f
spec:
  clusterIP: 192.168.103.156
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx-dp
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

通过explain获得命令说明

[root@hdss7-21 ~]# kubectl explain service.metadata
KIND:     Service
VERSION:  v1

RESOURCE: metadata <Object>

DESCRIPTION:
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata

     ObjectMeta is metadata that all persisted resources must have, which
     includes all objects users must create.
     
 ……

通过声明式文件来生成svc资源

[root@hdss7-21 ~]# vi nginx-ds-svc.yaml

apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2020-07-01T04:12:24Z"
  labels:
    app: nginx-ds
  name: nginx-ds
  namespace: default
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx-ds
  type: ClusterIP



[root@hdss7-21 ~]# kubectl create -f nginx-ds-svc.yaml 
service/nginx-ds created

[root@hdss7-21 ~]# kubectl get svc -n default
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   192.168.0.1      <none>        443/TCP   4d22h
nginx-ds     ClusterIP   192.168.68.128   <none>        80/TCP    22s

# 通过查看svc资源，获得对应的资源清单信息
[root@hdss7-21 ~]# kubectl get svc nginx-ds -o yaml
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2020-07-02T02:08:17Z"
  labels:
    app: nginx-ds
  name: nginx-ds
  namespace: default
  resourceVersion: "78933"
  selfLink: /api/v1/namespaces/default/services/nginx-ds
  uid: ab03e099-e113-481f-b8e2-01f56be56e66
spec:
  clusterIP: 192.168.68.128
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx-ds
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

修改资源配置清单

# 离线修改
[root@hdss7-21 ~]# vi nginx-ds-svc.yaml 
[root@hdss7-21 ~]# kubectl apply -f nginx-ds-svc.yaml 


# 在线修改
[root@hdss7-21 ~]# kubectl edit svc nginx-ds
service/nginx-ds edited
[root@hdss7-21 ~]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   192.168.0.1      <none>        443/TCP   4d22h
nginx-ds     ClusterIP   192.168.68.128   <none>        801/TCP   7m28s

删除资源配置清单

[root@hdss7-21 ~]# kubectl delete -f nginx-ds-svc.yaml 
service "nginx-ds" deleted
[root@hdss7-21 ~]# kubectl get svc -n default
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   192.168.0.1   <none>        443/TCP   4d22h

注：
增、删、查采用陈述式(命令行)管理K8s
改采用声明式（yaml）管理k8s