Resolve "Data Races in Store"

Closes #86 (closed)

nucleus/controller.go

@@ -12,6 +12,9 @@ import (
 	"time"
 )
 
+var coreLock sync.RWMutex
+var coreOnce sync.Once
+
 // Core is the representation of the controllers core
 type Core struct {
 	// deprecated
@@ -84,8 +87,7 @@ func createPrincipalNetworkDomain(sbi SouthboundInterface) error {
 // Run calls initialize to start the controller
 func Run(ctx context.Context) error {
 	var initError error
-	var once sync.Once
-	once.Do(func() {
+	coreOnce.Do(func() {
 		initError = initialize()
 	})
 	if initError != nil {