[management] Avoid breaking single acc mode when switching domains (#5511)

* **Bug Fixes**
  * Fixed domain configuration handling in single account mode to properly retrieve and apply domain settings from account data.
  * Improved error handling when account data is unavailable with fallback to configured default domain.

* **Tests**
  * Added comprehensive test coverage for single account mode domain configuration scenarios, including edge cases for missing or unavailable account data.

management/server/account.go

@@ -1379,9 +1379,10 @@ func (am *DefaultAccountManager) GetAccountIDFromUserAuth(ctx context.Context, u
 	if am.singleAccountMode && am.singleAccountModeDomain != "" {
 		// This section is mostly related to self-hosted installations.
 		// We override incoming domain claims to group users under a single account.
-		userAuth.Domain = am.singleAccountModeDomain
+		err := am.updateUserAuthWithSingleMode(ctx, &userAuth)
-		userAuth.DomainCategory = types.PrivateCategory
+		if err != nil {
-		log.WithContext(ctx).Debugf("overriding JWT Domain and DomainCategory claims since single account mode is enabled")
+			return "", "", err
+		}
 	}
 
 	accountID, err := am.getAccountIDWithAuthorizationClaims(ctx, userAuth)
@@ -1414,6 +1415,35 @@ func (am *DefaultAccountManager) GetAccountIDFromUserAuth(ctx context.Context, u
 	return accountID, user.Id, nil
 }
 
+// updateUserAuthWithSingleMode modifies the userAuth with the single account domain, or if there is an existing account, with the domain of that account
+func (am *DefaultAccountManager) updateUserAuthWithSingleMode(ctx context.Context, userAuth *auth.UserAuth) error {
+	userAuth.DomainCategory = types.PrivateCategory
+	userAuth.Domain = am.singleAccountModeDomain
+
+	accountID, err := am.Store.GetAnyAccountID(ctx)
+	if err != nil {
+		if e, ok := status.FromError(err); !ok || e.Type() != status.NotFound {
+			return err
+		}
+		log.WithContext(ctx).Debugf("using singleAccountModeDomain to override JWT Domain and DomainCategory claims in single account mode")
+		return nil
+	}
+
+	if accountID == "" {
+		log.WithContext(ctx).Debugf("using singleAccountModeDomain to override JWT Domain and DomainCategory claims in single account mode")
+		return nil
+	}
+
+	domain, _, err := am.Store.GetAccountDomainAndCategory(ctx, store.LockingStrengthNone, accountID)
+	if err != nil {
+		return err
+	}
+	userAuth.Domain = domain
+
+	log.WithContext(ctx).Debugf("overriding JWT Domain and DomainCategory claims since single account mode is enabled")
+	return nil
+}
+
 // syncJWTGroups processes the JWT groups for a user, updates the account based on the groups,
 // and propagates changes to peers if group propagation is enabled.
 // requires userAuth to have been ValidateAndParseToken and EnsureUserAccessByJWTGroups by the AuthManager

management/server/account_test.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/golang/mock/gomock"
+	"github.com/netbirdio/netbird/shared/management/status"
 	"github.com/prometheus/client_golang/prometheus/push"
 	log "github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
@@ -3966,3 +3967,116 @@ func TestDefaultAccountManager_UpdateAccountSettings_NetworkRangeChange(t *testi
 		t.Fatal("UpdateAccountSettings deadlocked when changing NetworkRange")
 	}
 }
+
+func TestUpdateUserAuthWithSingleMode(t *testing.T) {
+	t.Run("sets defaults and overrides domain from store", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		t.Cleanup(ctrl.Finish)
+
+		mockStore := store.NewMockStore(ctrl)
+		mockStore.EXPECT().
+			GetAnyAccountID(gomock.Any()).
+			Return("account-1", nil)
+		mockStore.EXPECT().
+			GetAccountDomainAndCategory(gomock.Any(), store.LockingStrengthNone, "account-1").
+			Return("real-domain.com", "private", nil)
+
+		am := &DefaultAccountManager{
+			Store:                   mockStore,
+			singleAccountModeDomain: "fallback.com",
+		}
+
+		userAuth := &auth.UserAuth{}
+		err := am.updateUserAuthWithSingleMode(context.Background(), userAuth)
+		require.NoError(t, err)
+		assert.Equal(t, "real-domain.com", userAuth.Domain)
+		assert.Equal(t, types.PrivateCategory, userAuth.DomainCategory)
+	})
+
+	t.Run("falls back to singleAccountModeDomain when account ID is empty", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		t.Cleanup(ctrl.Finish)
+
+		mockStore := store.NewMockStore(ctrl)
+		mockStore.EXPECT().
+			GetAnyAccountID(gomock.Any()).
+			Return("", nil)
+
+		am := &DefaultAccountManager{
+			Store:                   mockStore,
+			singleAccountModeDomain: "fallback.com",
+		}
+
+		userAuth := &auth.UserAuth{}
+		err := am.updateUserAuthWithSingleMode(context.Background(), userAuth)
+		require.NoError(t, err)
+		assert.Equal(t, "fallback.com", userAuth.Domain)
+		assert.Equal(t, types.PrivateCategory, userAuth.DomainCategory)
+	})
+
+	t.Run("falls back to singleAccountModeDomain on NotFound error", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		t.Cleanup(ctrl.Finish)
+
+		mockStore := store.NewMockStore(ctrl)
+		mockStore.EXPECT().
+			GetAnyAccountID(gomock.Any()).
+			Return("", status.Errorf(status.NotFound, "no accounts"))
+
+		am := &DefaultAccountManager{
+			Store:                   mockStore,
+			singleAccountModeDomain: "fallback.com",
+		}
+
+		userAuth := &auth.UserAuth{}
+		err := am.updateUserAuthWithSingleMode(context.Background(), userAuth)
+		require.NoError(t, err)
+		assert.Equal(t, "fallback.com", userAuth.Domain)
+		assert.Equal(t, types.PrivateCategory, userAuth.DomainCategory)
+	})
+
+	t.Run("propagates non-NotFound error from GetAnyAccountID", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		t.Cleanup(ctrl.Finish)
+
+		mockStore := store.NewMockStore(ctrl)
+		mockStore.EXPECT().
+			GetAnyAccountID(gomock.Any()).
+			Return("", status.Errorf(status.Internal, "db down"))
+
+		am := &DefaultAccountManager{
+			Store:                   mockStore,
+			singleAccountModeDomain: "fallback.com",
+		}
+
+		userAuth := &auth.UserAuth{}
+		err := am.updateUserAuthWithSingleMode(context.Background(), userAuth)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "db down")
+		// Defaults should still be set before error path
+		assert.Equal(t, types.PrivateCategory, userAuth.DomainCategory)
+	})
+
+	t.Run("propagates error from GetAccountDomainAndCategory", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+		t.Cleanup(ctrl.Finish)
+
+		mockStore := store.NewMockStore(ctrl)
+		mockStore.EXPECT().
+			GetAnyAccountID(gomock.Any()).
+			Return("account-1", nil)
+		mockStore.EXPECT().
+			GetAccountDomainAndCategory(gomock.Any(), store.LockingStrengthNone, "account-1").
+			Return("", "", status.Errorf(status.Internal, "query failed"))
+
+		am := &DefaultAccountManager{
+			Store:                   mockStore,
+			singleAccountModeDomain: "fallback.com",
+		}
+
+		userAuth := &auth.UserAuth{}
+		err := am.updateUserAuthWithSingleMode(context.Background(), userAuth)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "query failed")
+	})
+}