Breaking stuff by introducting decorator & abstract base class stuff.

pillar/api/utils/storage.py

@@ -1,5 +1,6 @@
 """Utility for managing storage backends and files."""
 
+import abc
 import logging
 import os
 import shutil
@@ -8,6 +9,18 @@ from flask import current_app
 
 log = logging.getLogger(__name__)
 
+# Mapping from backend name to backend class
+backends = {}
+
+
+def register_backend(backend_name):
+    def wrapper(cls):
+        assert backend_name not in backends
+        backends[backend_name] = cls
+        return cls
+
+    return wrapper
+
 
 class StorageBackend(object):
     """Can be a GCS bucket or simply a project folder in Pillar
@@ -17,9 +30,16 @@ class StorageBackend(object):
 
     """
 
+    __metaclass__ = abc.ABCMeta
+
     def __init__(self, backend):
         self.backend = backend
 
+    @abc.abstractmethod
+    def upload_file(self, param1, param2, param3):
+        """docstuff"""
+        pass
+
 
 class FileInStorage(object):
     """A wrapper for file or blob objects.
@@ -35,6 +55,7 @@ class FileInStorage(object):
         self.size = None
 
 
+@register_backend('local')
 class PillarStorage(StorageBackend):
     def __init__(self, project_id):
         super(PillarStorage, self).__init__(backend='local')
@@ -58,3 +79,10 @@ class PillarStorageFile(FileInStorage):
             shutil.copyfileobj(uploaded_file, outfile)
 
         self.size = file_size
+
+
+def default_storage_backend():
+    from flask import current_app
+
+    backend_cls = backends[current_app.config['STORAGE_BACKEND']]
+    return backend_cls()