Feature 477 - Support Cloud Files public storage

*   Added configuration options to mediagoblin.ini
*   process_media supports the python-cloudfiles
    almost-file-like objects by wrapping them in a
    contextlib.contextmanager-decorated func.
*   storage now has the CloudFilesStorage
*   New dependency added to setup.py; `python-cloudfiles`

mediagoblin/process_media/__init__.py

@@ -19,6 +19,7 @@ from mediagoblin.db.util import ObjectId
 from celery.task import task
 
 from mediagoblin import mg_globals as mgg
+from contextlib import contextmanager
 
 
 THUMB_SIZE = 180, 180
@@ -31,6 +32,12 @@ def create_pub_filepath(entry, filename):
              unicode(entry['_id']),
              filename])
 
+@contextmanager
+def closing(callback):
+    try:
+        yield callback
+    finally:
+        pass
 
 @task
 def process_media_initial(media_id):
@@ -53,7 +60,7 @@ def process_media_initial(media_id):
     thumb_filepath = create_pub_filepath(entry, 'thumbnail.jpg')
 
     thumb_file = mgg.public_store.get_file(thumb_filepath, 'w')
-    with thumb_file:
+    with closing(thumb_file):
         thumb.save(thumb_file, "JPEG", quality=90)
 
     """
@@ -73,7 +80,7 @@ def process_media_initial(media_id):
         medium_filepath = create_pub_filepath(entry, 'medium.jpg')
 
         medium_file = mgg.public_store.get_file(medium_filepath, 'w')
-        with medium_file:
+        with closing(medium_file):
             medium.save(medium_file, "JPEG", quality=90)
             medium_processed = True
 
@@ -84,7 +91,7 @@ def process_media_initial(media_id):
     with queued_file:
         original_filepath = create_pub_filepath(entry, queued_filepath[-1])
         
-        with mgg.public_store.get_file(original_filepath, 'wb') as original_file:
+        with closing(mgg.public_store.get_file(original_filepath, 'wb')) as original_file:
             original_file.write(queued_file.read())
 
     mgg.queue_store.delete_file(queued_filepath)

mediagoblin/storage.py

@@ -19,6 +19,7 @@ import re
 import shutil
 import urlparse
 import uuid
+import cloudfiles
 
 from werkzeug.utils import secure_filename
 
@@ -161,6 +162,61 @@ class StorageInterface(object):
                     dest_file.write(source_file.read())
 
 
+class CloudFilesStorage(StorageInterface):
+    def __init__(self, **kwargs):
+        self.param_container = kwargs.get('cloudfiles_container')
+        self.param_user = kwargs.get('cloudfiles_user')
+        self.param_api_key = kwargs.get('cloudfiles_api_key')
+        self.param_host = kwargs.get('cloudfiles_host')
+        self.param_use_servicenet = kwargs.get('cloudfiles_use_servicenet')
+
+        if not self.param_host:
+            print('No CloudFiles host URL specified, defaulting to Rackspace US')
+
+        self.connection = cloudfiles.get_connection(
+            username=self.param_user,
+            api_key=self.param_api_key,
+            servicenet=True if self.param_use_servicenet == 'true' or \
+                self.param_use_servicenet == True else False)
+
+        if not self.param_container in [self.connection.get_container(self.param_container)]:
+            self.container = self.connection.create_container(self.param_container)
+            self.container.make_public(
+                ttl=60 * 60 * 2)
+        else:
+            self.container = self.connection.get_container(self.param_container)
+
+    def _resolve_filepath(self, filepath):
+            return '-'.join(
+                clean_listy_filepath(filepath))
+
+    def file_exists(self, filepath):
+        try:
+            object = self.container.get_object(
+                self._resolve_filepath(filepath))
+            return True
+        except cloudfiles.errors.NoSuchObject:
+            return False
+
+    def get_file(self, filepath, mode='r'):
+        try:
+            obj = self.container.get_object(
+                self._resolve_filepath(filepath))
+        except cloudfiles.errors.NoSuchObject:
+            obj = self.container.create_object(
+                self._resolve_filepath(filepath))
+
+        return obj
+
+    def delete_file(self, filepath):
+        # TODO: Also delete unused directories if empty (safely, with
+        # checks to avoid race conditions).
+        self.container.delete_object(filepath)
+
+    def file_url(self, filepath):
+        return self.get_file(filepath).public_uri()
+
+
 class BasicFileStorage(StorageInterface):
     """
     Basic local filesystem implementation of storage API