K8S Go Client: How do you list all the pods associated to a Service?

[buck.r...@gmail.com]

Given a namespace name, and a service name, I'd like to use the In-Cluster Golang API to list the pod addresses for those pods associated to a service.

Which APIs would I call to get this information? I'm not quite seeing how to do this.

Thanks in advance.

-Bob

[buck.r...@gmail.com]

I found an answer here for the record: https://stackoverflow.com/questions/41545123/how-to-get-pods-under-the-service-with-client-go-the-client-library-of-kubernete

[John Belamaric]

Are you sure you want pods and not endpoints?

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[Robert Buck]

Endpoints would work.

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[John Belamaric]

Ok, so you just need to query for the endpoints object with the same name as your service (in the same namespace). This also allows you to differentiate between ready and not ready pods.

[Robert Buck]

Such a query would look like?

[John Belamaric]

Based on https://github.com/kubernetes/client-go/tree/master/examples/out-of-cluster-client-configuration the code below works.

eps, err := clientset.CoreV1().Endpoints("default").List(metav1.ListOptions{FieldSelector:"metadata.name=kubernetes"})

Here is a simple program. For in-cluster you just change the way the config is created (uncomment the in-cluster line and get rid of the other stuff).

package main

import (

"flag"

"fmt"

"os"

"path/filepath"

metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

"k8s.io/client-go/kubernetes"

"k8s.io/client-go/tools/clientcmd"

"k8s.io/client-go/rest"

)

func oocConfig() (*rest.Config, error) {

var kubeconfig *string

if home := homeDir(); home != "" {

kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")

} else {

kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")

}

flag.Parse()

// use the current context in kubeconfig

return clientcmd.BuildConfigFromFlags("", *kubeconfig)

}

func main() {

// creates the in-cluster config

//config, err := rest.InClusterConfig()

config, err := oocConfig()

if err != nil {

panic(err.Error())

}

// creates the clientset

clientset, err := kubernetes.NewForConfig(config)

if err != nil {

panic(err.Error())

}

eps, err := clientset.CoreV1().Endpoints("default").List(metav1.ListOptions{FieldSelector:"metadata.name=kubernetes"})

if err != nil {

panic(err.Error())

}

fmt.Printf("%v\n", eps)

}

func homeDir() string {

if h := os.Getenv("HOME"); h != "" {

return h

}

return os.Getenv("USERPROFILE") // windows

}

[Robert Buck]

Sweet. Thank you!!! Jumping right on this.