etcd: Add a special magic option hack

Workaround some legacy code for now.

etcd/etcd.go

@@ -262,6 +262,9 @@ type EmbdEtcd struct { // EMBeddeD etcd
 	// NoNetwork causes this to use unix:// sockets instead of TCP for
 	// connections.
 	NoNetwork bool
+	// NoMagic turns off some things which aren't needed when used with a
+	// simple Seeds and NoServer option.
+	NoMagic bool
 
 	// Chooser is the implementation of the algorithm that decides which
 	// hosts to add or remove to grow and shrink the cluster.
@@ -418,6 +421,10 @@ func (obj *EmbdEtcd) Validate() error {
 		}
 	}
 
+	if obj.NoMagic && !obj.NoServer {
+		return fmt.Errorf("we need Magic if we're a Server")
+	}
+
 	if _, err := etcdUtil.CopyURLs(obj.Seeds); err != nil { // this will validate
 		return errwrap.Wrapf(err, "the Seeds are not valid")
 	}
@@ -1215,11 +1222,13 @@ func (obj *EmbdEtcd) Run() error {
 	obj.activateExit4.Ack()
 
 	// startup endpoints watcher (to learn about other servers)
-	ctx, cancel := context.WithCancel(unblockCtx)
-	defer cancel() // cleanup on close...
-	if err := obj.runEndpoints(ctx); err != nil {
-		obj.activateExit5.Ack()
-		return err
+	if !obj.NoMagic { // disable possibly buggy code for now
+		ctx, cancel := context.WithCancel(unblockCtx)
+		defer cancel() // cleanup on close...
+		if err := obj.runEndpoints(ctx); err != nil {
+			obj.activateExit5.Ack()
+			return err
+		}
 	}
 	obj.activateExit5.Ack()
 	// We don't set state, we only watch others, so nothing to defer close!