fix(scaleset): fix scale set creation 400 error from invalid label types

The GitHub API returns a 400 ArgumentNullException when creating scale
sets because Label.Type was set to invalid enum values ("scaleset",
"scope"). Leave Type empty so the library defaults to "System", matching
the official actions/scaleset examples.

Also adds RunnerSetting{DisableUpdate: true} and removes the redundant
RunnerGroupName field.

Author: whywaita

pkg/scaleset/manager.go

@@ -241,16 +241,15 @@ func (m *Manager) ensureScaleSet(ctx context.Context, client *scaleset.Client, n
 	// Create new scale set
 	logger.Logf(false, "[scaleset] creating new scale set: %s", name)
 
-	// Generate labels based on target scope
-	var labels []scaleset.Label
-	labels = append(labels, scaleset.Label{Type: "scaleset", Name: "scaleset"})
-	labels = append(labels, scaleset.Label{Type: "scope", Name: target.Scope})
+	labels := buildScaleSetLabels(name)
 
 	scaleSet, err = client.CreateRunnerScaleSet(ctx, &scaleset.RunnerScaleSet{
-		Name:            name,
-		RunnerGroupID:   runnerGroup.ID,
-		RunnerGroupName: m.cfg.RunnerGroupName,
-		Labels:          labels,
+		Name:          name,
+		RunnerGroupID: runnerGroup.ID,
+		Labels:        labels,
+		RunnerSetting: scaleset.RunnerSetting{
+			DisableUpdate: true,
+		},
 	})
 	if err != nil {
 		return 0, fmt.Errorf("failed to create scale set: %w", err)
@@ -296,3 +295,12 @@ func sanitizeScaleSetName(prefix, scope string) string {
 	sanitized = strings.Trim(sanitized, "-")
 	return fmt.Sprintf("%s-%s", prefix, sanitized)
 }
+
+// buildScaleSetLabels creates labels for a scale set.
+// Type is left empty so that the library's applyDefaultLabelTypes() sets it to "System".
+func buildScaleSetLabels(scaleSetName string) []scaleset.Label {
+	return []scaleset.Label{
+		{Name: "self-hosted"},
+		{Name: scaleSetName},
+	}
+}

pkg/scaleset/manager_test.go

@@ -220,6 +220,30 @@ func TestManager_DeferredCleanupDeletesOwnWrapper(t *testing.T) {
 	}
 }
 
+func TestBuildScaleSetLabels(t *testing.T) {
+	const scaleSetName = "myshoes-myorg-myrepo"
+
+	labels := buildScaleSetLabels(scaleSetName)
+
+	if len(labels) != 2 {
+		t.Fatalf("expected 2 labels, got %d", len(labels))
+	}
+
+	// Type must be empty so that the library sets it to "System"
+	for i, l := range labels {
+		if l.Type != "" {
+			t.Errorf("labels[%d].Type = %q, want empty string", i, l.Type)
+		}
+	}
+
+	if labels[0].Name != "self-hosted" {
+		t.Errorf("labels[0].Name = %q, want %q", labels[0].Name, "self-hosted")
+	}
+	if labels[1].Name != scaleSetName {
+		t.Errorf("labels[1].Name = %q, want %q", labels[1].Name, scaleSetName)
+	}
+}
+
 func TestManagerConfig_Fields(t *testing.T) {
 	cfg := ManagerConfig{
 		AppID:           12345,