bug: Make bus Initialize idempotent, add Reload

internal/agent/agent.go

@@ -68,7 +68,7 @@ func Run(opts ...Option) error {
 		}
 
 		// Re-load providers
-		bus.Manager.LoadProviders()
+		bus.Reload()
 		err = machine.CreateSentinel("bundles")
 		if !c.IgnoreBundleErrors && err != nil {
 			return err

internal/bus/bus.go

@@ -10,14 +10,24 @@ import (
 )
 
 // Manager is the bus instance manager, which subscribes plugins to events emitted.
-var Manager = &Bus{
-	Manager: pluggable.NewManager(
-		bus.AllEvents,
-	),
+var Manager = NewBus()
+
+func NewBus() *Bus {
+	return &Bus{
+		Manager: pluggable.NewManager(
+			bus.AllEvents,
+		),
+	}
+}
+
+func Reload() {
+	Manager = NewBus()
+	Manager.Initialize()
 }
 
 type Bus struct {
 	*pluggable.Manager
+	registered bool
 }
 
 func (b *Bus) LoadProviders() {
@@ -26,29 +36,32 @@ func (b *Bus) LoadProviders() {
 }
 
 func (b *Bus) Initialize() {
-	b.LoadProviders()
-	for i := range b.Manager.Events {
-		e := b.Manager.Events[i]
-		b.Manager.Response(e, func(p *pluggable.Plugin, r *pluggable.EventResponse) {
-			if os.Getenv("BUS_DEBUG") == "true" {
-				fmt.Println(
-					fmt.Sprintf("[provider event: %s]", e),
-					"received from",
-					p.Name,
-					"at",
-					p.Executable,
-					r,
-				)
-			}
-			if r.Errored() {
-				err := fmt.Sprintf("Provider %s at %s had an error: %s", p.Name, p.Executable, r.Error)
-				fmt.Println(err)
-				os.Exit(1)
-			} else {
-				if r.State != "" {
-					fmt.Println(fmt.Sprintf("[provider event: %s]", e), r.State)
+	if !b.registered {
+		b.LoadProviders()
+		for i := range b.Manager.Events {
+			e := b.Manager.Events[i]
+			b.Manager.Response(e, func(p *pluggable.Plugin, r *pluggable.EventResponse) {
+				if os.Getenv("BUS_DEBUG") == "true" {
+					fmt.Println(
+						fmt.Sprintf("[provider event: %s]", e),
+						"received from",
+						p.Name,
+						"at",
+						p.Executable,
+						r,
+					)
 				}
-			}
-		})
+				if r.Errored() {
+					err := fmt.Sprintf("Provider %s at %s had an error: %s", p.Name, p.Executable, r.Error)
+					fmt.Println(err)
+					os.Exit(1)
+				} else {
+					if r.State != "" {
+						fmt.Println(fmt.Sprintf("[provider event: %s]", e), r.State)
+					}
+				}
+			})
+		}
+		b.registered = true
 	}
 }