componentsregistry: use structure to store handlers (#1502)

To make it possible to mock registry in DSC reconcileComponents for
testing, implement registry as a structure. Make package level
wrappers on Add and ForEach methods which operate on the default
statically created registry.

This allows keep working with the default registry in a real system
without extra arguments like before. It's in init()s and in
main(). But code under test can accept testing version when needed.

Signed-off-by: Yauheni Kaliuta <[email protected]>

controllers/datasciencecluster/datasciencecluster_controller.go

@@ -101,7 +101,7 @@ func (r *DataScienceClusterReconciler) Reconcile(ctx context.Context, req ctrl.R
 	}
 
 	// deploy components
-	if err := r.reconcileComponents(ctx, instance); err != nil {
+	if err := r.reconcileComponents(ctx, instance, cr.DefaultRegistry()); err != nil {
 		log.Info(err.Error())
 		status.SetCondition(&instance.Status.Conditions, "Degraded", status.ReconcileFailed, err.Error(), corev1.ConditionTrue)
 	}
@@ -150,13 +150,16 @@ func (r *DataScienceClusterReconciler) validate(ctx context.Context, _ *dscv1.Da
 	return nil
 }
 
-func (r *DataScienceClusterReconciler) reconcileComponents(ctx context.Context, instance *dscv1.DataScienceCluster) error {
+func (r *DataScienceClusterReconciler) reconcileComponents(
+	ctx context.Context,
+	instance *dscv1.DataScienceCluster,
+	reg *cr.Registry) error {
 	log := logf.FromContext(ctx).WithName("DataScienceCluster")
 
 	notReadyComponents := make([]string, 0)
 
 	// all DSC defined components
-	componentErrors := cr.ForEach(func(component cr.ComponentHandler) error {
+	componentErrors := reg.ForEach(func(component cr.ComponentHandler) error {
 		ci, err := r.reconcileComponent(ctx, instance, component)
 		if err != nil {
 			return err

pkg/componentsregistry/componentsregistry.go

@@ -32,25 +32,43 @@ type ComponentHandler interface {
 	UpdateDSCStatus(dsc *dscv1.DataScienceCluster, obj client.Object) error
 }
 
-var registry = []ComponentHandler{}
+// Registry is a struct that maintains a list of registered ComponentHandlers.
+type Registry struct {
+	handlers []ComponentHandler
+}
+
+var r = &Registry{}
 
-// Add registers a new component handler
+// Add registers a new ComponentHandler to the registry.
 // not thread safe, supposed to be called during init.
-// TODO: check if init() can be called in parallel.
-func Add(ch ComponentHandler) {
-	registry = append(registry, ch)
+func (r *Registry) Add(ch ComponentHandler) {
+	r.handlers = append(r.handlers, ch)
 }
 
-// ForEach iterates over all registered component handlers
+// ForEach iterates over all registered ComponentHandlers and applies the given function.
+// If any handler returns an error, that error is collected and returned at the end.
 // With go1.23 probably https://go.dev/blog/range-functions can be used.
-func ForEach(f func(ch ComponentHandler) error) error {
+func (r *Registry) ForEach(f func(ch ComponentHandler) error) error {
 	var errs *multierror.Error
-	for _, ch := range registry {
+	for _, ch := range r.handlers {
 		errs = multierror.Append(errs, f(ch))
 	}
+
 	return errs.ErrorOrNil()
 }
 
+func Add(ch ComponentHandler) {
+	r.Add(ch)
+}
+
+func ForEach(f func(ch ComponentHandler) error) error {
+	return r.ForEach(f)
+}
+
+func DefaultRegistry() *Registry {
+	return r
+}
+
 func IsManaged(ch ComponentHandler, dsc *dscv1.DataScienceCluster) bool {
 	return ch.GetManagementState(dsc) == operatorv1.Managed
 }