how to display nodes information with a JSON request?

Question

I know how to use the API to perform simple request such as display node information selecting node by labels value.

For example : curl http://localhost:8080/api/v1/nodes?labelSelector=kubernetes.io/role%3Dworker3 Display informations about node whose role is worker3.

Is there a way to perform the same request using a JSON query ?

looked on the web to find a such example but did not find one.

Ralle Mc Black · Accepted Answer · 2023-01-10T21:24:07.743

0

You can query with kubectl by label. The Roles of the node are just labels.

To return in yaml format

 kubectl get nodes -l node-role.kubernetes.io/worker -o yaml

To return in json format

 kubectl get nodes -l node-role.kubernetes.io/worker -o json

Update
Querying the api with json you can do like so:

curl http://localhost:8080/api/v1/nodes?{"node.kubernetes.io/worker01":"worker01"}

This in my case returns this:

{
  "kind": "NodeList",
  "apiVersion": "v1",
  "metadata": {
    "resourceVersion": "317238"
  },
  "items": [
    {
      "metadata": {
        "name": "worker01",
        "uid": "a2bec224-361f-49e9-8bba-b3b172816d6e",
        "resourceVersion": "316653",
        "creationTimestamp": "2022-12-24T11:04:43Z",
        "labels": {
          "beta.kubernetes.io/arch": "amd64",
          "beta.kubernetes.io/os": "linux",
          "kubernetes.io/arch": "amd64",
          "kubernetes.io/hostname": "worker01",
          "kubernetes.io/os": "linux",
          "microk8s.io/cluster": "true",
          "node.kubernetes.io/microk8s-worker": "microk8s-worker"
        },

............

As you can see it works, but you must analyse 2 things generally.

the api version (can be different to v1, depends on the kubernetes version)
the labels and property name.

The example above comes from microk8s, here i havent even Roles defined.

kubectl get node
NAME       STATUS   ROLES    AGE   VERSION
master     Ready    <none>   17d   v1.25.4
worker01   Ready    <none>   17d   v1.25.4

So i looked for some label that could extract the required data.

edited Jan 10 '23 at 21:24

answered Jan 10 '23 at 12:09

Ralle Mc Black

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Indeed @ralle-mc-black. But I guess that what is possible with kubectl is doable by the REST API and especially by a GET request with a JSON body. – nizery Jan 10 '23 at 17:21
I updated it with a json query example. – Ralle Mc Black Jan 10 '23 at 21:04
a great thanks. I deploy kubernetes 1.25.0-00 and the api version is v1. – nizery Jan 10 '23 at 22:23
Could you also upvote my answer please. – Ralle Mc Black Jan 10 '23 at 22:25
I have not enough reputation for that if I understand correctly. – nizery Jan 11 '23 at 08:59
I understand, maybe you can do taht later, thanks. – Ralle Mc Black Jan 11 '23 at 09:17
Sure. The stackoverflow comment explains that my upvote is not possible but kept for "later". – nizery Jan 11 '23 at 09:20

how to display nodes information with a JSON request?

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