Fix nil panic when manager plugin starts up after vars plugin (docker…

…-archive#834)

Signed-off-by: David Chung <[email protected]>

docs/e2e/start-blocking.sh

@@ -14,13 +14,14 @@ export INFRAKIT_MANAGER_CONTROLLERS=ingress,nfs
 infrakit plugin start \
 	 manager:mystack \
 	 group \
-	 vars \
 	 combo \
 	 vanilla \
 	 simulator \
 	 ingress \
 	 simulator:nfs-auth \
 	 enrollment:nfs \
+	 vars \
+	 time \
 	 --log 5 --log-debug-V 500 --log-stack \
 	 --log-debug-match module=manager \
 	 --log-debug-match-exclude=false \

pkg/manager/manager.go

@@ -103,26 +103,20 @@ func initUpdatable(scope scope.Scope, options Options) metadata.Updatable {
 
 			log.Debug("looking up metadata backend", "name", options.Metadata)
 
-			var p metadata.Plugin
 			if options.Metadata.IsEmpty() {
 				// in-memory only
-				p = metadata_plugin.NewUpdatablePlugin(metadata_plugin.NewPluginFromData(data), writer)
-
 				log.Info("backend metadata is in memory only")
+				return metadata_plugin.NewUpdatablePlugin(metadata_plugin.NewPluginFromData(data), writer), nil
+			}
 
-			} else {
-
-				metadataCall, err := scope.Metadata(options.Metadata.String())
-				if err != nil {
-					return nil, err
-				}
-				p = metadataCall.Plugin
-
-				_, is := p.(metadata.Updatable)
-				log.Info("backend metadata", "name", options.Metadata, "plugin", p, "updatable", is)
-
+			metadataCall, err := scope.Metadata(options.Metadata.String())
+			if err != nil {
+				return nil, err
+			}
+			if metadataCall == nil {
+				return nil, fmt.Errorf("not running %v", options.Metadata.String())
 			}
-			return metadata_plugin.NewUpdatablePlugin(p, writer), nil
+			return metadata_plugin.NewUpdatablePlugin(metadataCall.Plugin, writer), nil
 		}, defaultPluginPollInterval)
 
 }