Get current resource usage of a pod in Kubernetes with Go client

Question

The kubernetes go client has tons of methods and I can't find how I can get the current CPU & RAM usage of a specific (or all pods).

Can someone tell me what methods I need to call to get the current usage for pods & nodes?

My NodeList:

nodes, err := clientset.CoreV1().Nodes().List(metav1.ListOptions{})

Kubernetes Go Client: https://github.com/kubernetes/client-go

Metrics package: https://github.com/kubernetes/kubernetes/tree/master/staging/src/k8s.io/metrics

As far as I got the metrics server implements the Kubernetes metrics package in order to fetch the resource usage from pods and nodes, but I couldn't figure out where & how they do it: https://github.com/kubernetes-incubator/metrics-server

Answer 1

here is an example.

package main

import (
    "fmt"

    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/tools/clientcmd"
    metrics "k8s.io/metrics/pkg/client/clientset/versioned"
)

func main() {
    var kubeconfig, master string //empty, assuming inClusterConfig
    config, err := clientcmd.BuildConfigFromFlags(master, kubeconfig)
    if err != nil {
        panic(err)
    }

    mc, err := metrics.NewForConfig(config)
    if err != nil {
        panic(err)
    }
    podMetrics, err := mc.MetricsV1beta1().PodMetricses(metav1.NamespaceAll).List(metav1.ListOptions{})
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    for _, podMetric := range podMetrics.Items {
        podContainers := podMetric.Containers
        for _, container := range podContainers {
            cpuQuantity, ok := container.Usage.Cpu().AsInt64()
            memQuantity, ok := container.Usage.Memory().AsInt64()
            if !ok {
                return
            }
            msg := fmt.Sprintf("Container Name: %s \n CPU usage: %d \n Memory usage: %d", container.Name, cpuQuantity, memQuantity)
            fmt.Println(msg)
        }

    }
}

Answer 2

It is correct that go-client does not have support for metrics type, but in the metrics package there is a pregenerated client that can be used for fetching metrics objects and assign them right away to the appropriate structure. The only thing you need to do first is to generate a config and pass it to metrics client. So a simple client for metrics would look like this:

package main


import (
    "k8s.io/client-go/tools/clientcmd"
    metrics "k8s.io/metrics/pkg/client/clientset/versioned"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)



func main() {
    var kubeconfig, master string //empty, assuming inClusterConfig
    config, err := clientcmd.BuildConfigFromFlags(master, kubeconfig)
    if err != nil{
        panic(err)
    }

    mc, err := metrics.NewForConfig(config)
    if err != nil {
        panic(err)
    }

    mc.MetricsV1beta1().NodeMetricses().Get("your node name", metav1.GetOptions{})
    mc.MetricsV1beta1().NodeMetricses().List(metav1.ListOptions{})
    mc.MetricsV1beta1().PodMetricses(metav1.NamespaceAll).List(metav1.ListOptions{})
    mc.MetricsV1beta1().PodMetricses(metav1.NamespaceAll).Get("your pod name", metav1.GetOptions{})
}

Each of the above methods from metric client returns an appropriate structure (you can check those here) and an error (if any) which you should process according to your requirements.