Add config option default_data_file

It is useful to specify local file instead of uri if we want to
use stackalytics locally.
This patch adds default_data_file for doing that.

Change-Id: I52953a7727da297c3648dc94f9ff4681c8fad170

stackalytics/processor/config.py

@@ -24,6 +24,9 @@ CONNECTION_OPTS = [
 ]
 
 PROCESSOR_OPTS = [
+    cfg.StrOpt('default-data-file',
+               help='Default data file. This file is used instead of '
+                    'default-data-uri if specifying.'),
     cfg.StrOpt('default-data-uri',
                default='https://git.openstack.org/cgit/'
                        'openstack/stackalytics/plain/etc/default_data.json',

stackalytics/processor/main.py

@@ -312,6 +312,9 @@ def main():
     runtime_storage_inst = runtime_storage.get_runtime_storage(
         cfg.CONF.runtime_storage_uri)
 
+    if cfg.CONF.default_data_file:
+        default_data = utils.read_json_from_file(cfg.CONF.default_data_file)
+    else:
         default_data = utils.read_json_from_uri(cfg.CONF.default_data_uri)
     if not default_data:
         LOG.critical('Unable to load default data')

stackalytics/processor/utils.py

@@ -22,6 +22,7 @@ import re
 import time
 
 import iso8601
+import json
 from oslo_config import cfg
 from oslo_log import log as logging
 import requests
@@ -151,6 +152,12 @@ def read_json_from_uri(uri, session=None):
                     {'error': e, 'uri': uri})
 
 
+def read_json_from_file(filename):
+    with open(filename) as json_data:
+        data = json.load(json_data)
+    return data
+
+
 def read_yaml_from_uri(uri):
     try:
         return yaml.safe_load(read_uri(uri))