Google Cloud Storage support

We introduce a new node_type, storage, which can support different file
storage backends and makes them available for browsing via dedicated
entry points in the application. We intend to keep pillar storage
agnostic and support both internal/local storages as well as
remote/hosted solutions.

pillar/application/modules/file_storage/__init__.py

@@ -1,22 +1,50 @@
 import os
+import json
 from multiprocessing import Process
 from bson import ObjectId
 from flask import request
 from flask import Blueprint
+from flask import abort
+from flask import jsonify
 from application import app
 from application import db
 from application import post_item
 from application.utils.imaging import generate_local_thumbnails
 from application.utils.imaging import get_video_data
 from application.utils.imaging import ffmpeg_encode
-
 from application.utils.storage import remote_storage_sync
+from application.utils.gcs import GoogleCloudStorageBucket
 
 file_storage = Blueprint('file_storage', __name__,
                         template_folder='templates',
                         static_folder='../../static/storage',)
 
 
+@file_storage.route('/gcs/<bucket_name>/<subdir>/')
+@file_storage.route('/gcs/<bucket_name>/<subdir>/<path:file_path>')
+def browse_gcs(bucket_name, subdir, file_path=None):
+    """Browse the content of a Google Cloud Storage bucket"""
+
+    # Initialize storage client
+    storage = GoogleCloudStorageBucket(bucket_name, subdir=subdir)
+    if file_path:
+        # If we provided a file_path, we try to fetch it
+        file_object = storage.Get(file_path)
+        if file_object:
+            # If it exists, return file properties in a dictionary
+            return jsonify(file_object)
+        else:
+            listing = storage.List(file_path)
+            return jsonify(listing)
+            # We always return an empty listing even if the directory does not
+            # exist. This can be changed later.
+            # return abort(404)
+
+    else:
+        listing = storage.List('')
+        return jsonify(listing)
+
+
 @file_storage.route('/build_thumbnails/<path:file_path>')
 def build_thumbnails(file_path=None, file_id=None):
     if file_path:
@@ -180,7 +208,7 @@ def process_file(src_file):
         p = Process(target=encode, args=(file_abs_path, variations, res_y))
         p.start()
     if mime_type != 'video':
-         # Sync the whole subfolder
+         # Sync the whole subdir
         sync_path = os.path.split(file_abs_path)[0]
     else:
         sync_path = file_abs_path