implement 'IsHelmVM' function based on presence of configmap

pkg/helmvm/util.go

@@ -1,11 +1,43 @@
 package helmvm
 
 import (
+	"context"
+	"fmt"
+	corev1 "k8s.io/api/core/v1"
+
+	kuberneteserrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 )
 
+const configMapName = "embedded-cluster-config"
+const configMapNamespace = "kube-system"
+
+// ReadConfigMap will read the embedded cluster config from a configmap
+func ReadConfigMap(client kubernetes.Interface) (*corev1.ConfigMap, error) {
+	return client.CoreV1().ConfigMaps(configMapNamespace).Get(context.TODO(), configMapName, metav1.GetOptions{})
+}
+
 func IsHelmVM(clientset kubernetes.Interface) (bool, error) {
-	return false, nil
+	if clientset == nil {
+		return false, fmt.Errorf("clientset is nil")
+	}
+
+	configMapExists := false
+	_, err := ReadConfigMap(clientset)
+	if err == nil {
+		configMapExists = true
+	} else if kuberneteserrors.IsNotFound(err) {
+		configMapExists = false
+	} else if kuberneteserrors.IsUnauthorized(err) {
+		configMapExists = false
+	} else if kuberneteserrors.IsForbidden(err) {
+		configMapExists = false
+	} else if err != nil {
+		return false, fmt.Errorf("failed to get embedded cluster configmap: %w", err)
+	}
+
+	return configMapExists, nil
 }
 
 func IsHA(clientset kubernetes.Interface) (bool, error) {