Linux学习-kubernetes之资源清单定义

资源：对象

• workload：Pod、ReplicaSet、Deployment、StatefulSet、DaemonSet、Job、Cronjob,…
• 服务发现及均衡：Service、Ingress
• 配置及存储：Volume、CSI
  • ConfigMap、Secret
  • DownwardAPI
• 集群级资源
  • NameSpace、Node、Role、ClusterRole、RoleBinding、ClusterRoleBinding
• 元数据型资源
  • HPA、PodTemplate、LimitRange

#获取apiServer所支持的apiversion
[root@master ~]# kubectl api-versions
admissionregistration.k8s.io/v1
apiextensions.k8s.io/v1
apiregistration.k8s.io/v1
apps/v1
authentication.k8s.io/v1
authorization.k8s.io/v1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1
coordination.k8s.io/v1
discovery.k8s.io/v1
discovery.k8s.io/v1beta1
events.k8s.io/v1
events.k8s.io/v1beta1
flowcontrol.apiserver.k8s.io/v1beta1
networking.k8s.io/v1
node.k8s.io/v1
node.k8s.io/v1beta1
policy/v1
policy/v1beta1
rbac.authorization.k8s.io/v1
scheduling.k8s.io/v1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1
[root@master ~]# kubectl get pods
NAME                            READY   STATUS             RESTARTS         AGE
client                          0/1     Error              0                23h
client-7c75c79d7c-h9994         0/1     CrashLoopBackOff   19 (2m14s ago)   23h
nginx                           1/1     Running            2 (9m13s ago)    37h
nginx-deploy-7c948bcff4-jclqg   1/1     Running            1 (9m11s ago)    24h
nginx-deploy-7c948bcff4-mczxp   1/1     Running            1 (9m13s ago)    24h
#输出为yaml格式
[root@master ~]# kubectl get pods nginx -o yaml
#版本号，group/版本号，默认group为核心组
apiVersion: v1
#kind表示使用何种资源
kind: Pod
#元数据
metadata:
  creationTimestamp: "2021-11-07T00:16:21Z"
  labels:
    run: nginx
  name: nginx
  namespace: default
  resourceVersion: "17833"
  uid: 8f1cd26f-b981-428f-a156-a92b7dee2cfd
#特性，用于定义目标资源所期望的目标状态(用户定义)
spec:
  containers:
  #容器使用的镜像
  - image: nginx:1.14
    imagePullPolicy: IfNotPresent
    #容器名称
    name: nginx
    ports:
    - containerPort: 80
      protocol: TCP
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-85lz5
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: node2
  preemptionPolicy: PreemptLowerPriority
  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: kube-api-access-85lz5
    projected:
      defaultMode: 420
      sources:
      - serviceAccountToken:
          expirationSeconds: 3607
          path: token
      - configMap:
          items:
          - key: ca.crt
            path: ca.crt
          name: kube-root-ca.crt
      - downwardAPI:
          items:
          - fieldRef:
              apiVersion: v1
              fieldPath: metadata.namespace
            path: namespace
#当前资源的当前状态(只读)
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2021-11-07T00:16:21Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2021-11-08T14:01:53Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2021-11-08T14:01:53Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2021-11-07T00:16:21Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: docker://ef084460d6dc3183abd768dc89dbbbb0d9a0fab5809220d02f97e9230819ddff
    image: nginx:1.14
    imageID: docker-pullable://nginx@sha256:f7988fb6c02e0ce69257d9bd9cf37ae20a60f1df7563c3a2a6abe24160306b8d
    lastState:
      terminated:
        containerID: docker://05be395a286ac086568ec8a80a8ce017c8165a46e0e27e2f7be1e302e1c5c2d2
        exitCode: 255
        finishedAt: "2021-11-08T14:01:16Z"
        reason: Error
        startedAt: "2021-11-07T13:18:48Z"
    name: nginx
    ready: true
    restartCount: 2
    started: true
    state:
      running:
        startedAt: "2021-11-08T14:01:52Z"
  hostIP: 192.168.88.103
  phase: Running
  podIP: 10.244.1.6
  podIPs:
  - ip: 10.244.1.6
  qosClass: BestEffort
  startTime: "2021-11-07T00:16:21Z"

#kubectl proxy命令就可以使API server监听在本地的8001端口上
[root@master ~]# kubectl proxy
Starting to serve on 127.0.0.1:8001
#通过curl访问本地资源，会返回json格式配置信息
[root@master ~]# curl http://localhost:8001/api/v1/namespaces/default/pods/myapp-7b595df7fc-9d92c

创建资源的方法：

• apiServer仅接收JSON格式的资源定义
• yaml格式提供配置清单，apiserver自动转化为JSON格式，然后提交

生成资源清单方法

#创建资源时生成yaml,--dry-run即空运行，-o yaml，生成yaml文件
[root@k8s-master ~]# kubectl create deployment web --image=nginx -o yaml --dry-run=client -o yaml
#通过已经创建的资源获得yaml文件
[root@k8s-master ~]# kubectl get deployment nginx -o yaml  >my2.yaml

资源的配置清单

• apiVersion[group/version]
• kind：资源类别
• metadata：元数据
  • name：必须是唯一的(同一类别下)
  • namespace：名称空间
  • labels：标签
  • annotation：注解
  • 每个资源的引用PATH
    • /api/GROUP/version/namespaces/NAMESPACE/TYPE/NAME
  • spec：期望的状态，disired state
  • status：当前状态(current state)本字段由kubernetes集群维护

#通过explain来查看pods资源如何定义
[root@master ~]# kubectl explain pods
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.
FIELDS:
   ... ...
   metadata	<Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
   ... ...
#注