First attempt at making config loadable through string config overrides in an env variable.

storage/__init__.py

@@ -0,0 +1,36 @@
+from storage.local import LocalStorage
+from storage.s3 import S3Storage
+from storage.fakestorage import FakeStorage
+
+
+class Storage(object):
+  def __init__(self, app=None):
+    self.app = app
+    if app is not None:
+      self.state = self.init_app(app)
+    else:
+      self.state = None
+
+  def init_app(self, app):
+    storage_type = app.config.get('STORAGE_TYPE', 'LocalStorage')
+    path = app.config.get('STORAGE_PATH', '')
+
+    if storage_type == 'LocalStorage':
+      storage = LocalStorage(path)
+
+    elif storage_type == 'S3Storage':
+      access_key = app.config.get('STORAGE_AWS_ACCESS_KEY', '')
+      secret_key = app.config.get('STORAGE_AWS_SECRET_KEY', '')
+      bucket = app.config.get('STORAGE_S3_BUCKET', '')
+      storage = S3Storage(path, access_key, secret_key, bucket)
+
+    else:
+      storage = FakeStorage()
+
+    # register extension with app
+    app.extensions = getattr(app, 'extensions', {})
+    app.extensions['storage'] = storage
+    return storage
+
+  def __getattr__(self, name):
+    return getattr(self.state, name, None)

storage/basestorage.py

@@ -1,7 +1,7 @@
 import tempfile
 
 
-class Storage(object):
+class BaseStorage(object):
 
   """Storage is organized as follow:
   $ROOT/images/<image_id>/json

storage/fakestorage.py

@@ -0,0 +1,24 @@
+from storage.basestorage import BaseStorage
+
+
+class FakeStorage(BaseStorage):
+  def _init_path(self, path=None, create=False):
+    return path
+
+  def get_content(self, path):
+    raise IOError('Fake files are fake!')
+
+  def put_content(self, path, content):
+    return path
+
+  def stream_read(self, path):
+    yield ''
+
+  def stream_write(self, path, fp):
+    pass
+
+  def remove(self, path):
+    pass
+
+  def exists(self, path):
+    return False

storage/local.py

@@ -2,85 +2,85 @@
 import os
 import shutil
 
-from basestorage import Storage
+from storage.basestorage import BaseStorage
 
 
-class LocalStorage(Storage):
+class LocalStorage(BaseStorage):
 
-    def __init__(self, storage_path):
-        self._root_path = storage_path
+  def __init__(self, storage_path):
+    self._root_path = storage_path
 
-    def _init_path(self, path=None, create=False):
-        path = os.path.join(self._root_path, path) if path else self._root_path
-        if create is True:
-            dirname = os.path.dirname(path)
-            if not os.path.exists(dirname):
-                os.makedirs(dirname)
-        return path
+  def _init_path(self, path=None, create=False):
+    path = os.path.join(self._root_path, path) if path else self._root_path
+    if create is True:
+      dirname = os.path.dirname(path)
+      if not os.path.exists(dirname):
+        os.makedirs(dirname)
+    return path
 
-    def get_content(self, path):
-        path = self._init_path(path)
-        with open(path, mode='r') as f:
-            return f.read()
+  def get_content(self, path):
+    path = self._init_path(path)
+    with open(path, mode='r') as f:
+      return f.read()
 
-    def put_content(self, path, content):
-        path = self._init_path(path, create=True)
-        with open(path, mode='w') as f:
-            f.write(content)
-        return path
+  def put_content(self, path, content):
+    path = self._init_path(path, create=True)
+    with open(path, mode='w') as f:
+      f.write(content)
+    return path
 
-    def stream_read(self, path):
-        path = self._init_path(path)
-        with open(path, mode='rb') as f:
-            while True:
-                buf = f.read(self.buffer_size)
-                if not buf:
-                    break
-                yield buf
+  def stream_read(self, path):
+    path = self._init_path(path)
+    with open(path, mode='rb') as f:
+      while True:
+        buf = f.read(self.buffer_size)
+        if not buf:
+          break
+        yield buf
 
-    def stream_read_file(self, path):
-        path = self._init_path(path)
-        return open(path, mode='rb')
+  def stream_read_file(self, path):
+    path = self._init_path(path)
+    return open(path, mode='rb')
 
-    def stream_write(self, path, fp):
-        # Size is mandatory
-        path = self._init_path(path, create=True)
-        with open(path, mode='wb') as f:
-            while True:
-                try:
-                    buf = fp.read(self.buffer_size)
-                    if not buf:
-                        break
-                    f.write(buf)
-                except IOError:
-                    break
-
-    def list_directory(self, path=None):
-        path = self._init_path(path)
-        prefix = path[len(self._root_path) + 1:] + '/'
-        exists = False
-        for d in os.listdir(path):
-            exists = True
-            yield prefix + d
-        if exists is False:
-            # Raises OSError even when the directory is empty
-            # (to be consistent with S3)
-            raise OSError('No such directory: \'{0}\''.format(path))
-
-    def exists(self, path):
-        path = self._init_path(path)
-        return os.path.exists(path)
-
-    def remove(self, path):
-        path = self._init_path(path)
-        if os.path.isdir(path):
-            shutil.rmtree(path)
-            return
+  def stream_write(self, path, fp):
+    # Size is mandatory
+    path = self._init_path(path, create=True)
+    with open(path, mode='wb') as f:
+      while True:
         try:
-            os.remove(path)
-        except OSError:
-            pass
+          buf = fp.read(self.buffer_size)
+          if not buf:
+            break
+          f.write(buf)
+        except IOError:
+          break
 
-    def get_size(self, path):
-        path = self._init_path(path)
-        return os.path.getsize(path)
+  def list_directory(self, path=None):
+    path = self._init_path(path)
+    prefix = path[len(self._root_path) + 1:] + '/'
+    exists = False
+    for d in os.listdir(path):
+      exists = True
+      yield prefix + d
+    if exists is False:
+      # Raises OSError even when the directory is empty
+      # (to be consistent with S3)
+      raise OSError('No such directory: \'{0}\''.format(path))
+
+  def exists(self, path):
+    path = self._init_path(path)
+    return os.path.exists(path)
+
+  def remove(self, path):
+    path = self._init_path(path)
+    if os.path.isdir(path):
+      shutil.rmtree(path)
+      return
+    try:
+      os.remove(path)
+    except OSError:
+      pass
+
+  def get_size(self, path):
+    path = self._init_path(path)
+    return os.path.getsize(path)

storage/s3.py

@@ -5,7 +5,7 @@ import logging
 import boto.s3.connection
 import boto.s3.key
 
-from storage.basestorage import Storage
+from storage.basestorage import BaseStorage
 
 
 logger = logging.getLogger(__name__)
@@ -32,7 +32,7 @@ class StreamReadKeyAsFile(object):
     return resp
 
 
-class S3Storage(Storage):
+class S3Storage(BaseStorage):
 
   def __init__(self, storage_path, s3_access_key, s3_secret_key, s3_bucket):
     self._initialized = False