如何使用官方Python客户端从Pod中找到同一节点上的所有Kubernetes Pod? [英] How to find all Kubernetes Pods on the same node from a Pod using the official Python client?

问题描述

如何使用官方的Python Kubernetes客户端获取与我自己的(特权)Pod在同一Kubernetes节点上运行的Pod的列表?也就是说，吊舱如何才能识别其正在运行的具体Kubernetes节点，然后仅在此节点上查询吊舱的完整列表?

解决方案

我在这里假设您已将Pod部署到集群，现在您要查询正在运行的节点. /p>

这实际上是两个不同的问题:

也就是说，广告连播如何识别其运行的具体Kubernetes节点

有两种方法可以执行此操作，

好的，现在您可以对正在运行的Pod使用Pod信息和节点信息.

，然后仅在此节点上查询Pod的完整列表

现在，您知道运行Pod的节点名称，使用python API查询运行在其上的Pod相对简单:

#!/usr/bin/env python
from kubernetes import client, config
import os

def main():

    # it works only if this script is run by K8s as a POD
    config.load_incluster_config()
    # use this outside pods
    # config.load_kube_config()

    # grab the node name from the pod environment vars
    node_name = os.environ.get('MY_NODE_NAME', None)

    v1 = client.CoreV1Api()
    print("Listing pods with their IPs on node: ", node_name)
    # field selectors are a string, you need to parse the fields from the pods here
    field_selector = 'spec.nodeName='+node_name
    ret = v1.list_pod_for_all_namespaces(watch=False, field_selector=field_selector)
    for i in ret.items:
        print("%s\t%s\t%s" %
              (i.status.pod_ip, i.metadata.namespace, i.metadata.name))


if __name__ == '__main__':
    main()

How can I get a list of the pods running on the same Kubernetes node as my own (privileged) pod, using the official Python Kubernetes client? That is, how can a pod identify the concrete Kubernetes node it is running on and then query for a full list of pods on this node only?

解决方案

I'm making the assumption here that you've deployed a pod to the cluster, and now you're trying to query the node it's running on.

This is actually two distinct problems:

That is, how can a pod identify the concrete Kubernetes node it is running on

There's two ways you can do this, but they both involved the downward API. You can either push the pod name down or push the node name down (or both). You need to do this first to enable the lookups you need. So the pod running the kubernetes python client needs to be deployed like so:

apiVersion: v1
kind: Pod
metadata:
  name: example-app
spec:
  containers:
    - name: python-kubernetes-client
      image: my-image
      command: [ "start_my_app" ]
      env:
        - name: MY_NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        - name: MY_POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
  restartPolicy: Never

Okay, so now you have the pod information and the node information available to your running pod.

and then query for a full list of pods on this node only

Now that you know the node name the pod is running on, querying for the pods running on it is relatively straightforward using the python API:

#!/usr/bin/env python
from kubernetes import client, config
import os

def main():

    # it works only if this script is run by K8s as a POD
    config.load_incluster_config()
    # use this outside pods
    # config.load_kube_config()

    # grab the node name from the pod environment vars
    node_name = os.environ.get('MY_NODE_NAME', None)

    v1 = client.CoreV1Api()
    print("Listing pods with their IPs on node: ", node_name)
    # field selectors are a string, you need to parse the fields from the pods here
    field_selector = 'spec.nodeName='+node_name
    ret = v1.list_pod_for_all_namespaces(watch=False, field_selector=field_selector)
    for i in ret.items:
        print("%s\t%s\t%s" %
              (i.status.pod_ip, i.metadata.namespace, i.metadata.name))


if __name__ == '__main__':
    main()

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