CORS-4516: Support setting universe domain in client options

providers/gce/gce.go

@@ -21,6 +21,7 @@ package gce
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"io"
 	"runtime"
@@ -558,9 +559,46 @@ func GenerateCloudConfig(configFile *ConfigFile) (cloudConfig *CloudConfig, err
 	return cloudConfig, err
 }
 
+// clientOptions returns GCP API client options for authentication.
+// A custom TokenSource set in the config, is used directly.
+// Otherwise, FindDefaultCredentials discovers credentials.
+// WithCredentialsJSON is preferred when available as it uses
+// self-signed JWTs, which may be necessary for custom universe domains.
+func clientOptions(ts oauth2.TokenSource) ([]option.ClientOption, error) {
+	if ts != nil {
+		return []option.ClientOption{option.WithTokenSource(ts)}, nil
+	}
+
+	creds, err := google.FindDefaultCredentials(context.Background(), compute.CloudPlatformScope)
+	if err != nil {
+		return nil, fmt.Errorf("failed to find default credentials: %w", err)
+	}
+
+	var opts []option.ClientOption
+	if len(creds.JSON) > 0 {
+		var f struct {
+			Type string `json:"type"`
+		}
+		if err := json.Unmarshal(creds.JSON, &f); err != nil {
+			return nil, fmt.Errorf("failed to parse credentials JSON: %w", err)
+		}
+		opts = []option.ClientOption{option.WithAuthCredentialsJSON(option.CredentialsType(f.Type), creds.JSON)}
+	} else {
+		opts = []option.ClientOption{option.WithCredentials(creds)}
+	}
+
+	if ud, err := creds.GetUniverseDomain(); err == nil {
+		opts = append(opts, option.WithUniverseDomain(ud))
+	} else {
+		klog.Warningf("Failed to get universe domain from credentials: %v", err)
+	}
+
+	return opts, nil
+}
+
 // CreateGCECloud creates a Cloud object using the specified parameters.
 // If no networkUrl is specified, loads networkName via rest call.
-// If no tokenSource is specified, uses oauth2.DefaultTokenSource.
+// If no tokenSource is specified, uses FindDefaultCredentials.
 // If managedZones is nil / empty all zones in the region will be managed.
 func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 	// If ManagedZones was empty at startup, it means the cluster was configured
@@ -580,19 +618,24 @@ func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 		config.NetworkProjectID = config.ProjectID
 	}
 
-	service, err := compute.NewService(context.Background(), option.WithTokenSource(config.TokenSource))
+	clientOpts, err := clientOptions(config.TokenSource)
+	if err != nil {
+		return nil, err
+	}
+
+	service, err := compute.NewService(context.Background(), clientOpts...)
 	if err != nil {
 		return nil, err
 	}
 	service.UserAgent = userAgent
 
-	serviceBeta, err := computebeta.NewService(context.Background(), option.WithTokenSource(config.TokenSource))
+	serviceBeta, err := computebeta.NewService(context.Background(), clientOpts...)
 	if err != nil {
 		return nil, err
 	}
 	serviceBeta.UserAgent = userAgent
 
-	serviceAlpha, err := computealpha.NewService(context.Background(), option.WithTokenSource(config.TokenSource))
+	serviceAlpha, err := computealpha.NewService(context.Background(), clientOpts...)
 	if err != nil {
 		return nil, err
 	}
@@ -610,7 +653,7 @@ func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 		}
 	}
 
-	containerService, err := container.NewService(context.Background(), option.WithTokenSource(config.TokenSource))
+	containerService, err := container.NewService(context.Background(), clientOpts...)
 	if err != nil {
 		return nil, err
 	}

providers/gce/gce_test.go

@@ -21,11 +21,15 @@ package gce
 
 import (
 	"context"
+	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"testing"
 
+	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
+	"google.golang.org/api/option"
 
 	cloudprovider "k8s.io/cloud-provider"
 )
@@ -496,6 +500,78 @@ func TestGenerateCloudConfigs(t *testing.T) {
 	}
 }
 
+// optionTypeName returns the unexported type name of a ClientOption using reflection.
+func optionTypeName(opt option.ClientOption) string {
+	t := reflect.TypeOf(opt)
+	if t.Kind() == reflect.Ptr {
+		return "*" + t.Elem().Name()
+	}
+	return t.Name()
+}
+
+// writeFakeCredentials writes a minimal service account JSON to a temp file
+// and sets GOOGLE_APPLICATION_CREDENTIALS to point at it.
+func writeFakeCredentials(t *testing.T) {
+	t.Helper()
+	fakeJSON := `{
+		"type": "service_account",
+		"project_id": "test-project",
+		"private_key_id": "key-id",
+		"private_key": "fake-key",
+		"client_email": "test@test-project.iam.gserviceaccount.com",
+		"client_id": "123456789",
+		"token_uri": "https://oauth2.googleapis.com/token"
+	}`
+	f := filepath.Join(t.TempDir(), "creds.json")
+	if err := os.WriteFile(f, []byte(fakeJSON), 0600); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("GOOGLE_APPLICATION_CREDENTIALS", f)
+}
+
+func TestClientOptions(t *testing.T) {
+	tests := []struct {
+		name         string
+		ts           oauth2.TokenSource
+		wantOptTypes []string
+	}{
+		{
+			name: "custom token source uses WithTokenSource",
+			ts:   oauth2.StaticTokenSource(&oauth2.Token{AccessToken: "test"}),
+			wantOptTypes: []string{
+				"withTokenSource",
+			},
+		},
+		{
+			name: "JSON credentials uses WithAuthCredentialsJSON",
+			wantOptTypes: []string{
+				"withAuthCredentialsJSON",
+				"withUniverseDomain",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			writeFakeCredentials(t)
+
+			opts, err := clientOptions(tt.ts)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			if len(opts) != len(tt.wantOptTypes) {
+				t.Fatalf("got %d options, want %d", len(opts), len(tt.wantOptTypes))
+			}
+			for i, wantType := range tt.wantOptTypes {
+				if got := optionTypeName(opts[i]); got != wantType {
+					t.Errorf("opts[%d] type = %s, want %s", i, got, wantType)
+				}
+			}
+		})
+	}
+}
+
 func TestNewAlphaFeatureGate(t *testing.T) {
 	testCases := []struct {
 		alphaFeatures  []string