K8s-Discovery

K8s Discovery, is an effort to reduce the boiler plate code for the client-go or kubernetes based cloud native GoLang developers.

The main aspect of this is around saving and cleaning the code for in-cluster and out-cluster configurations.

Usage

Run go get to get the k8s-discovery module as follows.

go get github.com/gkarthiks/k8s-discovery

Declare a variable as var k8s *discovery.K8s and initialize it as k8s, _ = discovery.NewK8s(). Now the k8s will hold the interface that will provide the clientset for Kubernetes communication that is pulled either via in-cluster or via kubeconfig file.

Available APIs at the moment

NewK8s: Will return a new kubernetes clientset's interface that is formulated either via in-cluster configuration or kubeconfog file.

GetVersion: Queries the Kubernetes for the version in v0.0.0-master+$Format:%h$

GetNamespace: Gets the namespace of the running pod if running inside the cluster, if outside returns based on the POD_NAMESPACE environment variable. This environment variable also takes precedence if provided in a pod.

Available client

K8s Discovery provides the client set for kubernetes client with hassle free configuration as well as the metrics client. The MetricsClientSet can be used to query the metrics against the containers. There is also a RestConfig exposed via discovery to make use of the rest api.

Example

package main

import (
	"context"
	"fmt"
	"log"
	"strconv"

	discovery "github.com/gkarthiks/k8s-discovery"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	metricsTypes "k8s.io/metrics/pkg/apis/metrics/v1beta1"
)

var (
	k8s *discovery.K8s
)

func main() {
	k8s, _ = discovery.NewK8s()
	namespace, _ := k8s.GetNamespace()
	version, _ := k8s.GetVersion()
	fmt.Printf("Specified Namespace: %s\n", namespace)
	fmt.Printf("Version of running Kubernetes: %s\n", version)
	
	
	
	
	cronJobs, err := k8s.Clientset.BatchV1beta1().CronJobs(namespace).List(context.Background(), metav1.ListOptions{})
	if err != nil {
		log.Panic(err.Error())
	}
	for idx, crons := range cronJobs.Items {
		fmt.Printf("%d -> %s\n", idx, crons.Name)
	}
	
	
	
	
	fmt.Println("==== Moving towards the metrics query ====")
	
	podMetrics, err := k8s.MetricsClientSet.MetricsV1beta1().PodMetricses(namespace).List(context.Background(), metav1.ListOptions{})
	if err != nil {
		panic(err)
	}

	var podMetric metricsTypes.PodMetrics
	getPodUsageMetrics := func(pod metricsTypes.PodMetrics) {
		for _, container := range pod.Containers {
			cpuQuantityDec := container.Usage.Cpu().AsDec().String()
			cpuUsageFloat, _ := strconv.ParseFloat(cpuQuantityDec, 64)

			fmt.Printf( "CPU Usage Float: %v\n", cpuUsageFloat)

			memoryQuantityDec := container.Usage.Memory().AsDec().String()
			memoryUsageFloat, _ := strconv.ParseFloat(memoryQuantityDec, 64)
			fmt.Printf("Memory Usage Float: %v\n\n", memoryUsageFloat)
		}
	}

	for _, podMetric = range podMetrics.Items {
		getPodUsageMetrics(podMetric)
	}
	
	
	
}

Note:

For GCP or managed kubernetes, you have to import the auth module, else an error message stating no Auth Provider found for name "gcp" will be thrown. The import looks like the below for the sample program. Special mention @ringods.

import (
	"context"
	"fmt"
	"log"
	"strconv"

	discovery "github.com/gkarthiks/k8s-discovery"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	metricsTypes "k8s.io/metrics/pkg/apis/metrics/v1beta1"
	_ "k8s.io/client-go/plugin/pkg/client/auth"
)

Contributing

For contributions please refer the contributing guidelines.