Adds KUBECONFIG field for using existing .kube/config

internal/terraform/config/config.go

@@ -13,11 +13,21 @@ import (
 	"github.com/kubernetes-sigs/aws-iam-authenticator/pkg/token"
 	"github.com/pkg/errors"
 	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
 )
 
 // Func which configures the Kubernetes provider.
 // https://github.com/terraform-providers/terraform-provider-kubernetes/blob/master/kubernetes/provider.go
 func Func(d *schema.ResourceData) (interface{}, error) {
+	if v, ok := d.GetOk(FieldKubeConfig); ok {
+		cfg, err := clientcmd.BuildConfigFromFlags("", v.(string))
+		if err != nil {
+			return nil, err
+		}
+
+		return NewForConfig(cfg)
+	}
+
 	cfg := &rest.Config{}
 
 	// Overriding with static configuration

internal/terraform/config/fields.go

@@ -3,6 +3,8 @@ package config
 import "github.com/hashicorp/terraform/helper/schema"
 
 const (
+	// FieldKubeConfig defines the path to the Kubernetes config file.
+	FieldKubeConfig = "kubeconfig"
 	// FieldHost identifier for host field.
 	FieldHost = "host"
 	// FieldInsecure identifier for insecure field.
@@ -20,6 +22,12 @@ const (
 // Fields which are used to configure the Kubernetes client.
 func Fields() map[string]*schema.Schema {
 	return map[string]*schema.Schema{
+		FieldKubeConfig: {
+			Type:        schema.TypeString,
+			Optional:    true,
+			DefaultFunc: schema.EnvDefaultFunc("KUBECONFIG", ""),
+			Description: "The path to the Kubernetes config file.",
+		},
 		FieldHost: {
 			Type:        schema.TypeString,
 			Optional:    true,