make metadata indexing optional

while indexing the rally results to ES make the metadata indexing
optional.

now we can remove the metadata field in browbeat-config.yml and
disable the metadata indexing.

Change-Id: I68fcf4153f79bc321d920203525fea228fa0e996

browbeat/elastic.py

@@ -73,22 +73,20 @@ class Elastic(object):
         return json_data
 
     def combine_metadata(self, result):
-        if (self.config['elasticsearch']['metadata_files'] is not None and
-                len(self.config['elasticsearch']['metadata_files']) > 0):
-            meta = self.config['elasticsearch']['metadata_files']
-            for _meta in meta:
-                try:
-                    with open(_meta['file']) as jdata:
-                        result[_meta['name']] = json.load(jdata)
-                except Exception:
-                    self.logger.error(
-                        "Error loading Metadata file : {}".format(
-                            _meta['file']))
-                    self.logger.error(
-                        "Please make sure the metadata file exists and"
-                        " is valid JSON or run the playbook ansible/gather/site.yml"
-                        " before running the Browbeat test Suite")
-                    sys.exit(1)
+        meta = self.config['elasticsearch'].get('metadata_files', []) or []
+        for _meta in meta:
+            try:
+                with open(_meta['file']) as jdata:
+                    result[_meta['name']] = json.load(jdata)
+            except Exception:
+                self.logger.error(
+                    "Error loading Metadata file : {}".format(
+                        _meta['file']))
+                self.logger.error(
+                    "Please make sure the metadata file exists and"
+                    " is valid JSON or run the playbook ansible/gather/site.yml"
+                    " before running the Browbeat test Suite")
+                sys.exit(1)
         return result
 
     # Used to transform the cache dict into an elastic insertable iterable

browbeat/schema/browbeat.yml

@@ -62,7 +62,7 @@ mapping:
         required: True
       metadata_files:
         type: seq
-        required: True
+        required: False
         sequence:
           - type: map
             mapping:

browbeat/tools.py

@@ -70,7 +70,7 @@ class Tools(object):
         workloads.run_workload(copy.deepcopy(workload), run_iteration)
 
     def check_metadata(self):
-        meta = self.config['elasticsearch']['metadata_files']
+        meta = self.config['elasticsearch'].get('metadata_files', []) or []
         for _meta in meta:
             if not os.path.isfile(_meta['file']):
                 self.logger.info(