Validate manifest in plugin, fix rollback error

plugins/prebootstrapped/__init__.py

@@ -20,4 +20,10 @@ def rollback_tasks(tasklist, tasks_completed, manifest):
 		if task in completed and counter not in completed:
 			tasklist.add(counter())
 
-	counter_task(ebs.CreateVolumeFromSnapshot, ebs.DeleteVolume)
+	counter_task(CreateVolumeFromSnapshot, ebs.DeleteVolume)
+
+
+def validate_manifest(data, schema_validate):
+	from os import path
+	schema_path = path.normpath(path.join(path.dirname(__file__), 'manifest-schema.json'))
+	schema_validate(data, schema_path)

plugins/prebootstrapped/manifest-schema.json

@@ -0,0 +1,23 @@
+{
+	"$schema": "http://json-schema.org/draft-04/schema#",
+	"title": "Prebootstrapped plugin manifest",
+	"type": "object",
+	"properties": {
+		"plugins": {
+			"type": "object",
+			"properties": {
+				"prebootstrapped": {
+					"type": "object",
+					"properties": {
+						"snapshot": {
+							"type": "string"
+						}
+					},
+					"required": ["snapshot"]
+				}
+			},
+			"required": ["prebootstrapped"]
+		}
+	},
+	"required": ["plugins"]
+}