Remove interfaces and add extra info to instance

internal/plugin/factory.go

@@ -152,6 +152,12 @@ func RubyFactory(
 // Instance is the result generated by the factory. This lets us pack
 // a bit more information into plugin-launched components.
 type Instance struct {
+	// Plugin name providing this component
+	Name string
+
+	// Type of component provided in this instance
+	Type component.Type
+
 	// Component is the dispensed component
 	Component interface{}
 
@@ -161,15 +167,22 @@ type Instance struct {
 	// The GRPCBroker attached to this plugin
 	Broker *plugin.GRPCBroker
 
+	// Parent component
+	Parent *Instance
+
 	// Closer is a function that should be called to clean up resources
 	// associated with this plugin.
 	Close func()
 }
 
-type PluginMetadata interface {
-	SetRequestMetadata(k, v string)
+func (i *Instance) Parents() []string {
+	n := []string{}
+	for p := i; p != nil; p = p.Parent {
+		n = append(n, p.Name)
+	}
+	return n
 }
 
-type hasGRPCBroker interface {
-	GRPCBroker() *plugin.GRPCBroker
+func (i *Instance) ParentCount() int {
+	return len(i.Parents())
 }