gokuberneteskubernetes-hpa

How to extract the active HPA in Kubernetes using go-lang


I am using a kube config file to fetch the pod CPU and MEM data using go-lang. I am stuck to fetch the HPA details, i.e I am trying to write the equivalent of "kubectl get hpa", so I can know I have applied hpa to known services or not.

Any help on this is highly appreciated.

I have tried the below so far.

kubeClient "k8s.io/client-go/kubernetes/typed/autoscaling/v1"
hpaWatch, err := kubeClient.AutoscalingV1().HorizontalPodAutoscalers("default").Watch(metav1.ListOptions{})

But this is not working.


Solution

  • Here is the line you should have used:

    hpas, err := clientset.AutoscalingV1().HorizontalPodAutoscalers("default").List(context.TODO(), metav1.ListOptions{})
    

    and the following is a complete and working example for listing HPAs. You should be able just copy-paste it and run it.

    It was tested with client-go@0.19.0.

    package main
    
    import (
        "context"
        "flag"
        "fmt"
        "os"
        "path/filepath"
        "time"
    
        metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
        "k8s.io/client-go/kubernetes"
        "k8s.io/client-go/tools/clientcmd"
    )
    
    func main() {
        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
        config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
        if err != nil {
            panic(err.Error())
        }
    
        // create the clientset
        clientset, err := kubernetes.NewForConfig(config)
        if err != nil {
            panic(err.Error())
        }
        for {
            hpas, err := clientset.AutoscalingV1().HorizontalPodAutoscalers("default").List(context.TODO(), metav1.ListOptions{})
            if err != nil {
                panic(err.Error())
            }
    
            for _, hpa := range hpas.Items {
                fmt.Printf("%q\n", hpa.GetName())
            }
    
            time.Sleep(10 * time.Second)
        }
    }
    
    func homeDir() string {
        if h := os.Getenv("HOME"); h != "" {
            return h
        }
        return os.Getenv("USERPROFILE") // windows
    }