Kubectl运维脚本核心命令jsonpath的使用详解

清疚 2024-03-17 19:52 118阅读 0赞

## 1. jsonpath的语法介绍 ##

Kubectl 支持 JSONPath 模板。

JSONPath 模板由 \{\} 包起来的 JSONPath 表达式组成。Kubectl 使用 JSONPath 表达式来过滤 JSON 对象中的特定字段并格式化输出。除了原始的 JSONPath 模板语法，以下函数和语法也是有效的:

1.  使用双引号将 JSONPath 表达式内的文本引起来。
2.  使用 `range`，`end` 运算符来迭代列表。
3.  使用负片索引后退列表。负索引不会"环绕"列表，并且只要 `-index + listLength> = 0` 就有效。

<table> 
 <thead> 
 <tr> 
 <th> 函数 </th> 
 <th> 描述 </th> 
 <th> 示例 </th> 
 <th> 结果 </th> 
 </tr> 
 </thead> 
 <tbody> 
 <tr> 
 <td> text </td> 
 <td> 纯文本 </td> 
 <td> kind is {.kind} </td> 
 <td> kind is List </td> 
 </tr> 
 <tr> 
 <td> @ </td> 
 <td> 当前对象 </td> 
 <td> {@} </td> 
 <td> 与输入相同 </td> 
 </tr> 
 <tr> 
 <td> .&nbsp;or&nbsp;[] </td> 
 <td> 子运算符 </td> 
 <td> {.kind}&nbsp;or&nbsp;{['kind']} </td> 
 <td> List </td> 
 </tr> 
 <tr> 
 <td> .. </td> 
 <td> 递归下降 </td> 
 <td> {..name} </td> 
 <td> 127.0.0.1 127.0.0.2 myself e2e </td> 
 </tr> 
 <tr> 
 <td> * </td> 
 <td> 通配符。获取所有对象 </td> 
 <td> {.items[*].metadata.name} </td> 
 <td> [127.0.0.1 127.0.0.2] </td> 
 </tr> 
 <tr> 
 <td> [start:end :step] </td> 
 <td> 下标运算符 </td> 
 <td> {.users[0].name} </td> 
 <td> myself </td> 
 </tr> 
 <tr> 
 <td> [,] </td> 
 <td> 并集运算符 </td> 
 <td> {.items[*]['metadata.name', 'status.capacity']} </td> 
 <td> 127.0.0.1 127.0.0.2 map[cpu:4] map[cpu:8] </td> 
 </tr> 
 <tr> 
 <td> ?() </td> 
 <td> 过滤 </td> 
 <td> {.users[?(@.name=="e2e")].user.password} </td> 
 <td> secret </td> 
 </tr> 
 <tr> 
 <td> range,&nbsp;end </td> 
 <td> 迭代列表 </td> 
 <td> {range .items[*]}[{.metadata.name}, {.status.capacity}] {end} </td> 
 <td> [127.0.0.1, map[cpu:4]] [127.0.0.2, map[cpu:8]] </td> 
 </tr> 
 <tr> 
 <td> '' </td> 
 <td> 引用解释执行字符串 </td> 
 <td> {range .items[*]}{.metadata.name}{'\t'}{end} </td> 
 <td> 127.0.0.1 127.0.0.2 </td> 
 </tr> 
 </tbody> 
</table>

下面我们在k8s中使用jsonpath来获取我们想要的内容

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o json
    {
        "apiVersion": "v1",
        "kind": "Pod",
        "metadata": {
            "annotations": {
                "tke.cloud.tencent.com/networks-status": "[{\n    \"name\": \"tke-bridge\",\n    \"ips\": [\n        \"172.16.3.92\"\n    ],\n    \"default\": true,\n    \"dns\": {}\n}]"
            },
            "creationTimestamp": "2020-08-25T09:15:55Z",
            "generateName": "redis-5b4495ddb4-",
            "labels": {
                "k8s-app": "redis",
                "pod-template-hash": "5b4495ddb4",
                "qcloud-app": "redis"
            },
            "name": "redis-5b4495ddb4-szjtz",
            "namespace": "default",
            "ownerReferences": [
                {
                    "apiVersion": "apps/v1",
                    "blockOwnerDeletion": true,
                    "controller": true,
                    "kind": "ReplicaSet",
                    "name": "redis-5b4495ddb4",
                    "uid": "bef91151-d94e-46d5-a8a9-59a8f3ae634e"
                }
            ],
            "resourceVersion": "12100505479",
            "selfLink": "/api/v1/namespaces/default/pods/redis-5b4495ddb4-szjtz",
            "uid": "968a56ba-80ed-41d3-ad27-deb7d060bfe7"
        },
        "spec": {
            "containers": [
                {
                    "image": "redis",
                    "imagePullPolicy": "Always",
                    "name": "redis",
                    "resources": {
                        "limits": {
                            "cpu": "500m",
                            "memory": "1Gi"
                        },
                        "requests": {
                            "cpu": "250m",
                            "memory": "256Mi"
                        }
                    },
                    "securityContext": {
                        "privileged": false
                    },
                    "terminationMessagePath": "/dev/termination-log",
                    "terminationMessagePolicy": "File",
                    "volumeMounts": [
                        {
                            "mountPath": "/var/run/secrets/kubernetes.io/serviceaccount",
                            "name": "default-token-cl2h8",
                            "readOnly": true
                        }
                    ]
                }
            ],
            "dnsPolicy": "ClusterFirst",
            "enableServiceLinks": true,
            "imagePullSecrets": [
                {
                    "name": "qcloudregistrykey"
                }
            ],
            "nodeName": "10.168.1.4",
            "restartPolicy": "Always",
            "schedulerName": "default-scheduler",
            "securityContext": {},
            "serviceAccount": "default",
            "serviceAccountName": "default",
            "terminationGracePeriodSeconds": 30,
            "volumes": [
                {
                    "name": "default-token-cl2h8",
                    "secret": {
                        "defaultMode": 420,
                        "secretName": "default-token-cl2h8"
                    }
                }
            ]
        },
        "status": {
            "conditions": [
                {
                    "lastProbeTime": null,
                    "lastTransitionTime": "2020-08-25T09:15:55Z",
                    "status": "True",
                    "type": "Initialized"
                },
                {
                    "lastProbeTime": null,
                    "lastTransitionTime": "2020-08-25T09:15:59Z",
                    "status": "True",
                    "type": "Ready"
                },
                {
                    "lastProbeTime": null,
                    "lastTransitionTime": "2020-08-25T09:15:59Z",
                    "status": "True",
                    "type": "ContainersReady"
                },
                {
                    "lastProbeTime": null,
                    "lastTransitionTime": "2020-08-25T09:15:55Z",
                    "status": "True",
                    "type": "PodScheduled"
                }
            ],
            "containerStatuses": [
                {
                    "containerID": "docker://0a4540282684c9dd282d13eba9a4ae44433f625e65ef40473cda7ca00b2ea73e",
                    "image": "redis:latest",
                    "imageID": "docker-pullable://redis@sha256:09c33840ec47815dc0351f1eca3befe741d7105b3e95bc8fdb9a7e4985b9e1e5",
                    "lastState": {},
                    "name": "redis",
                    "ready": true,
                    "restartCount": 0,
                    "started": true,
                    "state": {
                        "running": {
                            "startedAt": "2020-08-25T09:15:59Z"
                        }
                    }
                }
            ],
            "hostIP": "10.168.1.4",
            "phase": "Running",
            "podIP": "172.16.3.92",
            "podIPs": [
                {
                    "ip": "172.16.3.92"
                }
            ],
            "qosClass": "Burstable",
            "startTime": "2020-08-25T09:15:55Z"
        }
    }

## 2. 通过jsonpath获取信息示例 ##

### 2.1 纯文本方式 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='kind is {.kind}'
    kind is Pod

### 2.2 获取当前对象 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={@}
 map[apiVersion:v1 kind:Pod metadata:map[annotations:map[tke.cloud.tencent.com/networks-status:[{
 "name": "tke-bridge",
 "ips": [
 "172.16.3.92"
 ],
 "default": true,
 "dns": {}
 }]] creationTimestamp:2020-08-25T09:15:55Z generateName:redis-5b4495ddb4- labels:map[k8s-app:redis pod-template-hash:5b4495ddb4 qcloud-app:redis] name:redis-5b4495ddb4-szjtz namespace:default ownerReferences:[map[apiVersion:apps/v1 blockOwnerDeletion:true controller:true kind:ReplicaSet name:redis-5b4495ddb4 uid:bef91151-d94e-46d5-a8a9-59a8f3ae634e]] resourceVersion:12100505479 selfLink:/api/v1/namespaces/default/pods/redis-5b4495ddb4-szjtz uid:968a56ba-80ed-41d3-ad27-deb7d060bfe7] spec:map[containers:[map[image:redis imagePullPolicy:Always name:redis resources:map[limits:map[cpu:500m memory:1Gi] requests:map[cpu:250m memory:256Mi]] securityContext:map[privileged:false] terminationMessagePath:/dev/termination-log terminationMessagePolicy:File volumeMounts:[map[mountPath:/var/run/secrets/kubernetes.io/serviceaccount name:default-token-cl2h8 readOnly:true]]]] dnsPolicy:ClusterFirst enableServiceLinks:true imagePullSecrets:[map[name:qcloudregistrykey]] nodeName:10.168.1.4 restartPolicy:Always schedulerName:default-scheduler securityContext:map[] serviceAccount:default serviceAccountName:default terminationGracePeriodSeconds:30 volumes:[map[name:default-token-cl2h8 secret:map[defaultMode:420 secretName:default-token-cl2h8]]]] status:map[conditions:[map[lastProbeTime:<nil> lastTransitionTime:2020-08-25T09:15:55Z status:True type:Initialized] map[lastProbeTime:<nil> lastTransitionTime:2020-08-25T09:15:59Z status:True type:Ready] map[lastProbeTime:<nil> lastTransitionTime:2020-08-25T09:15:59Z status:True type:ContainersReady] map[lastProbeTime:<nil> lastTransitionTime:2020-08-25T09:15:55Z status:True type:PodScheduled]] containerStatuses:[map[containerID:docker://0a4540282684c9dd282d13eba9a4ae44433f625e65ef40473cda7ca00b2ea73e image:redis:latest imageID:docker-pullable://redis@sha256:09c33840ec47815dc0351f1eca3befe741d7105b3e95bc8fdb9a7e4985b9e1e5 lastState:map[] name:redis ready:true restartCount:0 started:true state:map[running:map[startedAt:2020-08-25T09:15:59Z]]]] hostIP:10.168.1.4 phase:Running podIP:172.16.3.92 podIPs:[map[ip:172.16.3.92]] qosClass:Burstable startTime:2020-08-25T09:15:55Z]]

### **2.3 获取pod的apiversion** ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{.apiVersion}'
    v1

### 2.4 获取pod的name ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{.metadata.name}'
    redis-5b4495ddb4-szjtz

### 2.5 递归获取yaml所有的name ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{..name}'
    qcloudregistrykey default-token-cl2h8 redis default-token-cl2h8 redis redis-5b4495ddb4-szjtz redis-5b4495ddb4

### 2.6 获取所有状态条件中的类型 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[*].type}
    Initialized Ready ContainersReady PodScheduled[

### 2.7 获取状态第一个条件的类型 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[0].type}
    Initialized

### 2.8 从第一个状态条件开始到最后一个结束，每隔2个获取一次 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[0:3:2].type}
    Initialized ContainersReady

### 2.8 获取状态条件中的状态和类型 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .status.conditions[*]}[{..status}, {..type}]{end}'
    [True, Initialized][True, Ready][True, ContainersReady][True, PodScheduled]

#### 2.9 空格和换行符的引用 ####

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .status.conditions[*]}[{..status}, {..type}]{"\n"}{end}'
    [True, Initialized]
    [True, Ready]
    [True, ContainersReady]
    [True, PodScheduled]

### 2.10 获取resources中的cpu值 ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .spec.containers[*].resources}[{..cpu}]{end}'
    [500m 250m]

### 2.11 获取resources中的cpu和memory ###

[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .spec.containers[*].resources}[{..cpu}, {..memory}]{end}'
    [500m 250m, 1Gi 256Mi]

### 2.22 获取promotheus这个pod中alertmanage的容器端口 ###

prometheus的yaml文件只截取部分

[root@VM_1_4_centos ~]# kubectl get pod prometheus-7674d56d7f-dqxfx -n kube-ops -o json
    {
        "apiVersion": "v1",
        "kind": "Pod",
        "metadata": {
            "name": "prometheus-7674d56d7f-dqxfx",
            "namespace": "kube-ops",
        },
        "spec": {
            "containers": [
                {
                    "args": [
                        "--config.file=/etc/alertmanager/config.yml",
                        "--storage.path=/alertmanager/data"
                    ],
                    "image": "prom/alertmanager:v0.15.3",
                    "imagePullPolicy": "IfNotPresent",
                    "name": "alertmanager",
                    "ports": [
                        {
                            "containerPort": 9093,
                            "name": "http",
                            "protocol": "TCP"
                        }
                    ],  
                 .........
                },
                {
                    "command": [
                        "/bin/prometheus"
                    ],
                    "image": "prom/prometheus:v2.4.3",
                    "imagePullPolicy": "IfNotPresent",
                    "name": "prometheus",
                    "ports": [
                        {
                            "containerPort": 9090,
                            "name": "http",
                            "protocol": "TCP"
                        }
                }
    .......

[root@VM_1_4_centos ~]# kubectl get pod prometheus-7674d56d7f-dqxfx -n kube-ops -o=jsonpath='{.spec.containers[?(@.name=="alertmanager")].ports}'
    [map[containerPort:9093 name:http protocol:TCP]]

### 2.23 获取所有的containerID和pod ip ###

kubectl get pods --all-namespaces    -o=jsonpath='{range .items[*]}[{.status.containerStatuses[0].containerID}, {.status.podIP}]{"\n"}{end}'

## 参考文档 ##

[JSONPath 支持 | Kubernetes][JSONPath _ _ Kubernetes]

[JSONPath _ _ Kubernetes]: https://kubernetes.io/zh/docs/reference/kubectl/jsonpath/