I'm having a bit of a challenge try to build my app which is using the golang client-go library. What the app does is provide and api which then deploys a pod to a kubernetes cluster. Now the app is able to deploy a pod successfully if I use an out of cluster kubernetes(i.e minikube) config which is found in $HOME/.kube/config. See code below that determines which config to use depending on the config path;

package kubernetesinterface

import (
	"log"
	"os"

	core "k8s.io/api/core/v1"
	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	"k8s.io/client-go/kubernetes"
	_ "k8s.io/client-go/plugin/pkg/client/auth" // load auth packages
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)

// KubeStruct - struct that uses interface type (useful when testing)
type KubeStruct struct {
	clientset kubernetes.Interface
}

// DeployPod - Method that uses a KubeStruct type to deploy deploy simulator pod to kubernetes cluster
func (kube *KubeStruct) DeployPod() bool {
	var podObject *core.Pod
	podObject = createPodObjects()
	_, err := kube.clientset.Core().Pods(podObject.Namespace).Create(podObject)
	if err != nil {
		log.Println("Failed to create simulator pod: ", err.Error())
		return false
	}

	return true
}

// GetNewClient - function to create a new clientset object to connect to a kubernetes cluster
func GetNewClient() (*KubeStruct, error) {
	var kubeConfig *rest.Config
	var err error
	configPath := os.Getenv("CONFIG_PATH")
	if configPath == "" {
		log.Println("Using in-cluster configuration")
		kubeConfig, err = rest.InClusterConfig()
	} else {
		log.Println("Using out of cluster config")
		kubeConfig, err = clientcmd.BuildConfigFromFlags("", configPath)
	}
	if err != nil {
		log.Println("Error getting configuration ", err.Error())
		return nil, err
	}
	// create clientset for kubernetes cluster
	client := KubeStruct{}
	client.clientset, err = kubernetes.NewForConfig(kubeConfig)
	if err != nil {
		log.Println("Error creating clientset for kubernetes cluster ", err.Error())
		return nil, err
	}

	return &client, nil

}

func createPodObjects() *core.Pod {
	return &core.Pod{
		ObjectMeta: v1.ObjectMeta{
			Name:      "podname",
			Namespace: "default",
			Labels: map[string]string{
				"app": "podname",
			},
		},
		Spec: core.PodSpec{
			Containers: []core.Container{
				{
					Name:            "podname",
					Image:           os.Getenv("IMAGE"),
					ImagePullPolicy: core.PullIfNotPresent,
					Command: []string{
						"sleep",
						"3600",
					},
				},
			},
		},
	}
}

So if a value exists for CONFIG_PATH, the app works as expected and a pod is deployed to my minikube cluster. Now when the same app is built on gcp, I get the following build error;

Step #1: 2019/03/13 21:25:20 Error getting configuration unable to load in-cluster configuration, KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT must be defined

I have searched online unsuccessfully for a solution so I thought I'd post here.