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-lxcfsplugincontroller-revision-hash: csi-attacher-lxcfsplugin-75c7658464statefulset.kubernetes.io/pod-name: csi-attacher-lxcfsplugin-0name: csi-attacher-lxcfsplugin-0namespace: lxcfs-csiownerReferences:- apiVersion: apps/v1blockOwnerDeletion: truecontroller: truekind: StatefulSetname: csi-attacher-lxcfspluginuid: c520c298-7c0f-40c5-9878-8ea47be81e4aresourceVersion: "34427971"uid: b64b595e-c2a5-49c8-8ef2-a9b9987b2fe3
spec:containers:- args:- --csi-address=$(ADDRESS)- --v=5env:- name: ADDRESSvalue: /var/lib/csi/sockets/pluginproxy/csi.sockimage: docker.io/lxcfs:v1imagePullPolicy: Nevername: csi-provisionerresources:limits:cpu: 150mmemory: 100Mirequests:cpu: 150mmemory: 100MiterminationMessagePath: /dev/termination-logterminationMessagePolicy: FilevolumeMounts:- mountPath: /var/lib/csi/sockets/pluginproxyname: socket-dir- mountPath: /var/run/secrets/kubernetes.io/serviceaccountname: kube-api-access-xsjrpreadOnly: true- args:- --v=5- --csi-address=$(ADDRESS)env:- name: ADDRESSvalue: /var/lib/csi/sockets/pluginproxy/csi.sockimage: docker.io/lxcfs:v1imagePullPolicy: Nevername: csi-attacherresources:limits:cpu: 150mmemory: 100Mirequests:cpu: 150mmemory: 100MiterminationMessagePath: /dev/termination-logterminationMessagePolicy: FilevolumeMounts:- mountPath: /var/lib/csi/sockets/pluginproxy/name: socket-dir- mountPath: /var/run/secrets/kubernetes.io/serviceaccountname: kube-api-access-xsjrpreadOnly: 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=10command:- /csi-serverenv:- name: NODE_IDvalueFrom:fieldRef:apiVersion: v1fieldPath: spec.nodeName- name: CSI_ENDPOINTvalue: unix://plugin/csi.sockimage: docker.io/lxcfs:v1imagePullPolicy: Nevername: csi-serverresources:limits:cpu: 150mmemory: 100Mirequests:cpu: 150mmemory: 100MiterminationMessagePath: /dev/termination-logterminationMessagePolicy: FilevolumeMounts:- mountPath: /pluginname: socket-dir- mountPath: /var/logname: log-volume- mountPath: /var/run/secrets/kubernetes.io/serviceaccountname: kube-api-access-xsjrpreadOnly: true- args:- /liveness/csi-livenessprobe --csiAddress=/var/lib/kubelet/plugins/csi-lxcfsplugin/csi.sock--httpEndpoint=127.0.0.1:10926command:- /bin/sh- -cimage: docker.io/lxcfs:v1imagePullPolicy: Nevername: health-checkresources:limits:cpu: 10mmemory: 100Mrequests:cpu: 10mmemory: 100MterminationMessagePath: /dev/termination-logterminationMessagePolicy: FilevolumeMounts:- mountPath: /plugin/name: socket-dir- mountPath: /var/run/secrets/kubernetes.io/serviceaccountname: kube-api-access-xsjrpreadOnly: truednsPolicy: ClusterFirstenableServiceLinks: truehostname: csi-attacher-lxcfsplugin-0nodeName: docker123nodeSelector:node-role.kubernetes.io/master: ""preemptionPolicy: PreemptLowerPrioritypriority: 1000000000priorityClassName: lxcfs-csi-priority-classrestartPolicy: AlwaysschedulerName: default-schedulersecurityContext: {}serviceAccount: csi-attacherserviceAccountName: csi-attachersubdomain: csi-attacherterminationGracePeriodSeconds: 30tolerations:- operator: Existsvolumes:- emptyDir: {}name: socket-dir- hostPath:path: /var/lib/docker/logs/lxcfs-csi-servertype: DirectoryOrCreatename: log-volume- name: kube-api-access-xsjrpprojected:defaultMode: 420sources:- serviceAccountToken:expirationSeconds: 3607path: token- configMap:items:- key: ca.crtpath: ca.crtname: kube-root-ca.crt- downwardAPI:items:- fieldRef:apiVersion: v1fieldPath: metadata.namespacepath: namespace
status:conditions:- lastProbeTime: nulllastTransitionTime: "2024-04-17T06:33:35Z"status: "True"type: Initialized- lastProbeTime: nulllastTransitionTime: "2024-04-22T02:26:11Z"status: "True"type: Ready- lastProbeTime: nulllastTransitionTime: "2024-04-22T02:26:11Z"status: "True"type: ContainersReady- lastProbeTime: nulllastTransitionTime: "2024-04-17T06:33:35Z"status: "True"type: PodScheduledcontainerStatuses:- containerID: containerd://3c0eeb141059a8dc099c1d3c4c98a6a6f25b855335b319a240f167983b5c00f4image: docker.io/lxcfs:v1imageID: sha256:19ec336305e47bfd0f64a7d1eb17dc01cb67cbbb856dbf18307999208c70c80blastState: {}name: csi-attacherready: truerestartCount: 0started: truestate:running:startedAt: "2024-04-22T02:25:41Z"- containerID: containerd://aa0dd18c42e1e6ecade723a358856e8705cf20ebc418290e74ec0c76325fd78aimage: docker.io/lxcfs:v1imageID: sha256:1011f81cb57bccc5591e54874ca3a16e0b20a8f80765ee2bab2eb55d3782e84elastState: {}name: csi-provisionerready: truerestartCount: 0started: truestate:running:startedAt: "2024-04-22T02:25:41Z"- containerID: containerd://23465fdf825016cefb4982c3367d9e34839f60707e2ecb57b4b6e617d3b341e0image: docker.io/lxcfs:v1imageID: sha256:e28f1150ab6c9bcf294be21403faf6862ad460891408a628ac23102d5f29b61dlastState: {}name: csi-serverready: truerestartCount: 0started: truestate:running:startedAt: "2024-04-22T02:25:56Z"- containerID: containerd://116a11be9a0b548bd04589c59228702043f0d3b1dad39a11f25f1aa1d68378beimage: docker.io/lxcfs:v1imageID: sha256:f9cf76b861fe4ba215a07ac5851d43aea7247996490992e38176e51ada755dd3lastState: {}name: health-checkready: truerestartCount: 0started: truestate:running:startedAt: "2024-04-22T02:26:11Z"hostIP: 11.166.91.187phase: RunningpodIP: 10.244.0.54podIPs:- ip: 10.244.0.54qosClass: GuaranteedstartTime: "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}'
10m6、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
