render terminal ui of cluster usage metrics

k8s-metrics.go

package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strconv"

	ui "github.com/gizak/termui/v3"
	"github.com/gizak/termui/v3/widgets"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	metrics "k8s.io/metrics/pkg/client/clientset/versioned"
)

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()

	if err := ui.Init(); err != nil {
		log.Fatalf("failed to initialize termui: %v", err)
	}
	defer ui.Close()

	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		panic(err)
	}
	coreClient, err := kubernetes.NewForConfig(config)

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

	nodeMetrics, err := mc.MetricsV1beta1().NodeMetricses().List(metav1.ListOptions{})
	if err != nil {
		fmt.Println("Error:", err)
		return
	}
	for _, nodeMetric := range nodeMetrics.Items {
		nodeData, _ := coreClient.CoreV1().Nodes().Get(nodeMetric.Name, metav1.GetOptions{})
		pods, _ := coreClient.CoreV1().Pods("").List(metav1.ListOptions{
			FieldSelector: fmt.Sprintf("spec.nodeName=%v", nodeMetric.Name),
		})

		cpuTotal := nodeData.Status.Allocatable.Cpu().MilliValue()
		cpuUsed := nodeMetric.Usage.Cpu().MilliValue()
		cpu := float64(cpuUsed) / float64(cpuTotal)

		memTotal, _ := nodeData.Status.Allocatable.Memory().AsInt64()
		memUsed, _ := nodeMetric.Usage.Memory().AsInt64()
		mem := float64(memUsed) / float64(memTotal)

		table := widgets.NewTable()
		table.Rows = [][]string{
			[]string{"Nodes", "CPU", "Memory", "Pods"},
			[]string{nodeMetric.Name, fmt.Sprintf("%f%%", cpu*100), fmt.Sprintf("%f%%", mem*100), strconv.Itoa(len(pods.Items))},
		}
		table.TextStyle = ui.NewStyle(ui.ColorWhite)
		table.RowSeparator = true
		table.SetRect(0, 0, 60, 10)

		p := widgets.NewParagraph()
		p.Text = "Cluster Resource Utilization"
		p.SetRect(0, 13, 60, 10)
		p.Border = true

		ui.Render(table, p, createCPUGraph("CPU", cpu), createMemGraph("Mem", mem))

		uiEvents := ui.PollEvents()
		for {
			e := <-uiEvents
			switch e.ID {
			case "q", "<C-c>":
				return
			}
		}
		//storage, _ := nodeMetric.Usage.StorageEphemeral().AsInt64()
	}
}

func createCPUGraph(name string, val float64) *widgets.Gauge {
	w := widgets.NewGauge()
	w.Title = name
	w.SetRect(0, 13, 30, 18)
	w.Percent = int(val * 100)
	w.BarColor = ui.ColorGreen
	w.BorderStyle.Fg = ui.ColorWhite
	w.TitleStyle.Fg = ui.ColorCyan
	return w
}

func createMemGraph(name string, val float64) *widgets.Gauge {
	w := widgets.NewGauge()
	w.Title = name
	w.SetRect(60, 13, 30, 18)
	w.Percent = int(val * 100)
	w.BarColor = ui.ColorGreen
	w.BorderStyle.Fg = ui.ColorWhite
	w.TitleStyle.Fg = ui.ColorCyan
	return w

}

func homeDir() string {
	if h := os.Getenv("HOME"); h != "" {
		return h
	}
	return os.Getenv("USERPROFILE") // windows
}