Kubectl命令行jsonpath的使用

本篇文章主要介绍了jsonpath的语法和使用。

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

下面我们在k8s中使用jsonpath来获取我们想要的内容

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
[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"
    }
}

通过jsonpath获取信息示例

纯文本方式

1
2
3
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='kind is {.kind}'
kind is Pod

获取当前对象

1
2
3
4
5
6
7
8
9
[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]]

获取pod的apiversion

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{.apiVersion}'
v1

获取pod的name

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{.metadata.name}'
redis-5b4495ddb4-szjtz

递归获取yaml所有的name

1
2
[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

获取所有状态条件中的类型

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[*].type}
Initialized Ready ContainersReady PodScheduled[

获取状态第一个条件的类型

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[0].type}
Initialized

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

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath={.status.conditions[0:3:2].type}
Initialized ContainersReady

获取状态条件中的状态和类型

1
2
[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]

空格和换行符的引用

1
2
3
4
5
[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]

获取request中的cpu值

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .spec.containers[0].resources}[{..cpu}]{end}'
[500m 250m]

获取request中的cpu和memory

1
2
[root@VM_1_4_centos ~]# kubectl get pod redis-5b4495ddb4-szjtz -o=jsonpath='{range .spec.containers[0].resources}[{..cpu}, {..memory}]{end}'
[500m 250m, 1Gi 256Mi]

获取promotheus这个pod中alertmanage的容器端口

prometheus的yaml文件只截取部分

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
[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]]

参考文档

https://kubernetes.io/zh/docs/reference/kubectl/jsonpath/

Kubernetes
#Kubernetes #kubectl
Kubectl命令行jsonpath的使用
https://www.niewx.cn/2020/08/27/2020-08-27-Use-of-Kubectl-command-line-jsonpath/
作者
VashonNie
发布于
2020年8月27日
许可协议