refactor: returns err when CloudMeta is not initialzied with providers.

pkg/cloudmeta/metadata.go

@@ -49,8 +49,14 @@ func NewCloudMeta() (*CloudMeta, error) {
 	}, nil
 }
 
+// ErrNoProviders will be returned by CloudMeta service, when it hasn't been initialized with any metadata provider.
+var ErrNoProviders = errors.New("no metadata providers found")
+
 // GetInstanceMetadata tries to fetch instance metadata from AWS, GCP, Azure providers in order.
 func (cloud *CloudMeta) GetInstanceMetadata(ctx context.Context) (InstanceMetadata, error) {
+	if len(cloud.providers) == 0 {
+		return InstanceMetadata{}, ErrNoProviders
+	}
 	var mErr error
 	for _, provider := range cloud.providers {
 		meta, err := cloud.runWithTimeout(ctx, provider)

pkg/cloudmeta/metadata_test.go

@@ -4,6 +4,7 @@ package cloudmeta
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"testing"
 )
@@ -13,8 +14,8 @@ func TestGetInstanceMetadata(t *testing.T) {
 		cloudmeta := &CloudMeta{}
 
 		meta, err := cloudmeta.GetInstanceMetadata(context.Background())
-		if err != nil {
-			t.Fatalf("unexpected err: %v", err)
+		if !errors.Is(err, ErrNoProviders) {
+			t.Fatalf("expected err, got: %v", err)
 		}
 		if meta.InstanceType != "" {
 			t.Fatalf("meta.InstanceType should be empty, got %v", meta.InstanceType)