如何将 kubectl 的输出格式化为 JSON

Question

kubectl get 命令有这个标志 -o 来格式化输出。

是否有类似的方法来格式化 kubectl describe 命令的输出？

例如：

kubectl describe -o="jsonpath={...}" pods my-rc

将为 my-rc 复制控制器中的 pods 列表打印 JSON 格式。但是 -o 不被 describe 命令接受。

Answer 1

根据kubectl help describe的输出，似乎不支持结构化输出：

$ kubectl help describe
Show details of a specific resource or group of resources.

This command joins many API calls together to form a detailed description of a
given resource or group of resources.

$ kubectl describe TYPE NAME_PREFIX

will first check for an exact match on TYPE and NAME_PREFIX. If no such resource
exists, it will output details for every resource that has a name prefixed with NAME_PREFIX

Possible resource types include (case insensitive): pods (po), services (svc), deployments,
replicasets (rs), replicationcontrollers (rc), nodes (no), events (ev), limitranges (limits),
persistentvolumes (pv), persistentvolumeclaims (pvc), resourcequotas (quota), namespaces (ns),
serviceaccounts, ingresses (ing), horizontalpodautoscalers (hpa), daemonsets (ds), configmaps,
componentstatuses (cs), endpoints (ep), and secrets.

Usage:
  kubectl describe (-f FILENAME | TYPE [NAME_PREFIX | -l label] | TYPE/NAME) [flags]

Examples:
# Describe a node
kubectl describe nodes kubernetes-minion-emt8.c.myproject.internal

# Describe a pod
kubectl describe pods/nginx

# Describe a pod identified by type and name in "pod.json"
kubectl describe -f pod.json

# Describe all pods
kubectl describe pods

# Describe pods by label name=myLabel
kubectl describe po -l name=myLabel

# Describe all pods managed by the 'frontend' replication controller (rc-created pods
# get the name of the rc as a prefix in the pod the name).
kubectl describe pods frontend

Flags:
  -f, --filename=[]: Filename, directory, or URL to a file containing the resource to describe
  -l, --selector="": Selector (label query) to filter on

Global Flags:
      --alsologtostderr[=false]: log to standard error as well as files
      --certificate-authority="": Path to a cert. file for the certificate authority.
      --client-certificate="": Path to a client certificate file for TLS.
      --client-key="": Path to a client key file for TLS.
      --cluster="": The name of the kubeconfig cluster to use
      --context="": The name of the kubeconfig context to use
      --insecure-skip-tls-verify[=false]: If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure.
      --kubeconfig="": Path to the kubeconfig file to use for CLI requests.
      --log-backtrace-at=:0: when logging hits line file:N, emit a stack trace
      --log-dir="": If non-empty, write log files in this directory
      --log-flush-frequency=5s: Maximum number of seconds between log flushes
      --logtostderr[=true]: log to standard error instead of files
      --match-server-version[=false]: Require server version to match client version
      --namespace="": If present, the namespace scope for this CLI request.
      --password="": Password for basic authentication to the API server.
  -s, --server="": The address and port of the Kubernetes API server
      --stderrthreshold=2: logs at or above this threshold go to stderr
      --token="": Bearer token for authentication to the API server.
      --user="": The name of the kubeconfig user to use
      --username="": Username for basic authentication to the API server.
      --v=0: log level for V logs
      --vmodule=: comma-separated list of pattern=N settings for file-filtered logging

Answer 2

kubectl describe 不支持 -o 或等效项。它应该是人类可读的而不是脚本友好的。您可以实现您用 kubectl get pods -l <selector_of_your_rc> -o <output_format> 描述的内容，例如：

$ kubectl get pods -l app=guestbook,tier=frontend -o name
pod/frontend-a4kjz
pod/frontend-am1ua
pod/frontend-yz2dq

Answer 3

在我的例子中，我需要从服务中获取负载均衡器地址。我使用 kubectl get service:

做到了

$ kubectl -n <namespace> -ojson get service <service>

{
    "apiVersion": "v1",
    "kind": "Service",
    [...]
    "status": {
        "loadBalancer": {
            "ingress": [
                {
                    "hostname": "internal-xxxxxxxxxxxxxxxxxxxxxxxxxxx-yyyyyyyyyy.us-east-1.elb.amazonaws.com"
                }
     [...]
}

Answer 4

正如@janekuto 所建议的那样

describe cannot be used to display data in json format

请看我的回答here. jq is really a powerful utility to play around with json display of kubectl. You can do so much with jq不用太费力

kubectl - format the resource quota values in json format

Answer 5

kubectl 不支持 -o yaml/json for describe，但你仍然可以使用其他一些命令来获取 describe 中的信息，例如：

kubectl get events

如何将 kubectl 的输出格式化为 JSON

How to format the output of kubectl describe to JSON

output-formatting

kubernetes

kubectl