k8s解析数据 -o=jsonpath=‘{}‘ 的使用

kubectl -o=jsonpath= 是 Kubernetes 命令行工具 kubectl 中的一个输出选项，用于以 JSONPath 格式提取并展示 API 对象的部分内容。JSONPath 是一种查询语言，它允许用户在 JSON 结构中导航和提取数据。这对于自动化脚本和快速查询 Kubernetes 资源的特定部分非常有用。

当你执行 kubectl 命令并使用 -o 或 --output 标志时，可以指定输出格式。如果后面跟的是 jsonpath= ，那么你就可以提供一个 JSONPath 表达式来精确地选择你想要从资源描述中提取的信息。

基本语法结构如下：

kubectl [command] [resource] [-o=jsonpath='{expression}']

这里的 expression 是一个遵循 JSONPath 语法的字符串，用于指定要提取的数据路径。例如：

• {.metadata.name} 会提取对象的名称。
• {.spec.containers[*].name} 会提取所有容器的名称，如果有多个容器的话。
• {range .spec.containers[*]}{.name}{"\n"}{end} 使用 range 来迭代每个容器，并打印它们的名称，每个名称后跟一个换行符。

JSONPath 表达式中常用的符号包括：

• . 访问对象的属性。
• [] 访问数组元素或作为筛选条件。
• {} 定义表达式或者用于创建输出模板。
• * 通配符，匹配数组中的所有元素。
• @ 引用当前对象。

通过这种方式，kubectl -o=jsonpath= 提供了一种灵活且强大的方法来查看 Kubernetes 资源的定制化视图。

示例如下：

kubectl get pod  csi-attacher-lxcfsplugin-0 -o yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2024-04-17T06:33:35Z"
  generateName: csi-attacher-lxcfsplugin-
  labels:
    app: csi-attacher-lxcfsplugin
    controller-revision-hash: csi-attacher-lxcfsplugin-75c7658464
    statefulset.kubernetes.io/pod-name: csi-attacher-lxcfsplugin-0
  name: csi-attacher-lxcfsplugin-0
  namespace: lxcfs-csi
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: StatefulSet
    name: csi-attacher-lxcfsplugin
    uid: c520c298-7c0f-40c5-9878-8ea47be81e4a
  resourceVersion: "34427971"
  uid: b64b595e-c2a5-49c8-8ef2-a9b9987b2fe3
spec:
  containers:
  - args:
    - --csi-address=$(ADDRESS)
    - --v=5
    env:
    - name: ADDRESS
      value: /var/lib/csi/sockets/pluginproxy/csi.sock
    image: docker.io/lxcfs:v1
    imagePullPolicy: Never
    name: csi-provisioner
    resources:
      limits:
        cpu: 150m
        memory: 100Mi
      requests:
        cpu: 150m
        memory: 100Mi
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/lib/csi/sockets/pluginproxy
      name: socket-dir
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-xsjrp
      readOnly: true
  - args:
    - --v=5
    - --csi-address=$(ADDRESS)
    env:
    - name: ADDRESS
      value: /var/lib/csi/sockets/pluginproxy/csi.sock
    image: docker.io/lxcfs:v1
    imagePullPolicy: Never
    name: csi-attacher
    resources:
      limits:
        cpu: 150m
        memory: 100Mi
      requests:
        cpu: 150m
        memory: 100Mi
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/lib/csi/sockets/pluginproxy/
      name: socket-dir
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-xsjrp
      readOnly: true
  - args:
    - --nodeid=$(NODE_ID)
    - --endpoint=$(CSI_ENDPOINT)
    - --log-retain-date=5
    - --log-compress
    - --log-file-path=/var/log/controller.log
    - --log-max-size=200
    - --log-max-backups=10
    command:
    - /csi-server
    env:
    - name: NODE_ID
      valueFrom:
        fieldRef:
          apiVersion: v1
          fieldPath: spec.nodeName
    - name: CSI_ENDPOINT
      value: unix://plugin/csi.sock
    image: docker.io/lxcfs:v1
    imagePullPolicy: Never
    name: csi-server
    resources:
      limits:
        cpu: 150m
        memory: 100Mi
      requests:
        cpu: 150m
        memory: 100Mi
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /plugin
      name: socket-dir
    - mountPath: /var/log
      name: log-volume
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-xsjrp
      readOnly: true
  - args:
    - /liveness/csi-livenessprobe --csiAddress=/var/lib/kubelet/plugins/csi-lxcfsplugin/csi.sock
      --httpEndpoint=127.0.0.1:10926
    command:
    - /bin/sh
    - -c
    image: docker.io/lxcfs:v1
    imagePullPolicy: Never
    name: health-check
    resources:
      limits:
        cpu: 10m
        memory: 100M
      requests:
        cpu: 10m
        memory: 100M
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /plugin/
      name: socket-dir
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-xsjrp
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  hostname: csi-attacher-lxcfsplugin-0
  nodeName: docker123
  nodeSelector:
    node-role.kubernetes.io/master: ""
  preemptionPolicy: PreemptLowerPriority
  priority: 1000000000
  priorityClassName: lxcfs-csi-priority-class
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {
    
    }
  serviceAccount: csi-attacher
  serviceAccountName: csi-attacher
  subdomain: csi-attacher
  terminationGracePeriodSeconds: 30
  tolerations:
  - operator: Exists
  volumes:
  - emptyDir: {
    
    }
    name: socket-dir
  - hostPath:
      path: /var/lib/docker/logs/lxcfs-csi-server
      type: DirectoryOrCreate
    name: log-volume
  - name: kube-api-access-xsjrp
    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
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2024-04-17T06:33:35Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2024-04-22T02:26:11Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2024-04-22T02:26:11Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2024-04-17T06:33:35Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: containerd://3c0eeb141059a8dc099c1d3c4c98a6a6f25b855335b319a240f167983b5c00f4
    image: docker.io/lxcfs:v1
    imageID: sha256:19ec336305e47bfd0f64a7d1eb17dc01cb67cbbb856dbf18307999208c70c80b
    lastState: {
    
    }
    name: csi-attacher
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2024-04-22T02:25:41Z"
  - containerID: containerd://aa0dd18c42e1e6ecade723a358856e8705cf20ebc418290e74ec0c76325fd78a
    image: docker.io/lxcfs:v1
    imageID: sha256:1011f81cb57bccc5591e54874ca3a16e0b20a8f80765ee2bab2eb55d3782e84e
    lastState: {
    
    }
    name: csi-provisioner
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2024-04-22T02:25:41Z"
  - containerID: containerd://23465fdf825016cefb4982c3367d9e34839f60707e2ecb57b4b6e617d3b341e0
    image: docker.io/lxcfs:v1
    imageID: sha256:e28f1150ab6c9bcf294be21403faf6862ad460891408a628ac23102d5f29b61d
    lastState: {
    
    }
    name: csi-server
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2024-04-22T02:25:56Z"
  - containerID: containerd://116a11be9a0b548bd04589c59228702043f0d3b1dad39a11f25f1aa1d68378be
    image: docker.io/lxcfs:v1
    imageID: sha256:f9cf76b861fe4ba215a07ac5851d43aea7247996490992e38176e51ada755dd3
    lastState: {
    
    }
    name: health-check
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2024-04-22T02:26:11Z"
  hostIP: 11.166.91.187
  phase: Running
  podIP: 10.244.0.54
  podIPs:
  - ip: 10.244.0.54
  qosClass: Guaranteed
  startTime: "2024-04-17T06:33:35Z"

1、获取kind

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.kind}'
Pod

2、获取metadata 中的 generateName

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.metadata.generateName}'
csi-attacher-lxcfsplugin-

3、获取metadata 中的labels中的app

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.metadata.labels.app}'
csi-attacher-lxcfsplugin

4、获取metadata 中的ownerReferences中的uid

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.metadata.ownerReferences}'
[{
    
    "apiVersion":"apps/v1","blockOwnerDeletion":true,"controller":true,"kind":"StatefulSet","name":"csi-attacher-lxcfsplugin","uid":"c520c298-7c0f-40c5-9878-8ea47be81e4a"}]
# 得到一个列表，且列表中只有一个值
$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.metadata.ownerReferences[0].uid}'
c520c298-7c0f-40c5-9878-8ea47be81e4a

5、获取spec 第四个containers中的resources中的requests中的cpu

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.spec.containers[3]}' 
{
    
    "args":["/liveness/csi-livenessprobe --csiAddress=/var/lib/kubelet/plugins/csi-lxcfsplugin/csi.sock --httpEndpoint=127.0.0.1:10926"],"command":["/bin/sh","-c"],"image":"reg.docker.alibaba-inc.com/alibaba_apsara_paas/lxcfs_csi_livenessprobe:unionbase-v1","imagePullPolicy":"Never","name":"health-check","resources":{
    
    "limits":{
    
    "cpu":"10m","memory":"100M"},"requests":{
    
    "cpu":"10m","memory":"100M"}},"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File","volumeMounts":[{
    
    "mountPath":"/plugin/","name":"socket-dir"},{
    
    "mountPath":"/var/run/secrets/kubernetes.io/serviceaccount","name":"kube-api-access-xsjrp","readOnly":true}]}

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.spec.containers[3].resources}' 
{
    
    "limits":{
    
    "cpu":"10m","memory":"100M"},"requests":{
    
    "cpu":"10m","memory":"100M"}}

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.spec.containers[3].resources.requests}' 
{
    
    "cpu":"10m","memory":"100M"}

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{.spec.containers[3].resources.requests.cpu}' 
10m

6、获取每一个容器的name

$ kubectl get pod  csi-attacher-lxcfsplugin-0 -o=jsonpath='{range .spec.containers[*]}{.name}{"\n"}{end}' 
csi-provisioner
csi-attacher
csi-server
health-check