Add validation of log property

Log property should have at least following forms
"message", "application_type" and "dimensions".
"application_type" and "dimensions" will be always set.
But "message" will not be always set.
So this validation checks log property has "message".

Change-Id: I9f7cfaf11906724a9cf555b77c61a690f44ddaaa

docs/monasca-log-api-spec.md

@@ -16,7 +16,7 @@ Create log.
 * X-Auth-Token (string, required) - Keystone auth token
 * Content-Type (string, required) - application/json; text/plain
 * X-Application-Type (string(255), optional) - Type of application
-* X-Dimensions ({string(255):string(255)}, optional) - A dictionary consisting of (key, value) pairs used to structure logs.
+* X-Dimensions ({string(255):string(255)}, required) - A dictionary consisting of (key, value) pairs used to structure logs.
 
 #### Path Parameters
 None.

monasca_log_api/tests/test_service.py

@@ -350,6 +350,30 @@ class EnvelopeSizeValidations(testing.TestBase):
         )
 
 
+class LogMessageValidations(testing.TestBase):
+
+    def test_should_pass_message_in_log_property(self):
+        log_object = {
+            'message': 'some messages',
+            'application_type': 'monasca-log-api',
+            'dimensions': {
+                'hostname': 'devstack'
+            }
+        }
+        common_service.Validations.validate_log_message(log_object)
+
+    @unittest.expectedFailure
+    def test_should_fail_pass_for_non_message_in_log_property(self):
+        log_object = {
+            'massage': 'some messages',
+            'application_type': 'monasca-log-api',
+            'dimensions': {
+                'hostname': 'devstack'
+            }
+        }
+        common_service.Validations.validate_log_message(log_object)
+
+
 class LogsCreatorNewLog(unittest.TestCase):
     def setUp(self):
         self.instance = common_service.LogCreator()

monasca_log_api/v2/common/service.py

@@ -262,6 +262,20 @@ class Validations(object):
                 description=u'Maximum allowed size is %d bytes' % max_size
             )
 
+    @staticmethod
+    def validate_log_message(log_object):
+        """Validates log property.
+
+        Log property should have message property.
+
+        Args:
+            log_object (dict): log property
+           """
+        if 'message' not in log_object:
+            raise exceptions.HTTPUnprocessableEntity(
+                'Log property should have message'
+            )
+
 
 class LogCreator(object):
     """Transforms logs,
@@ -343,6 +357,8 @@ class LogCreator(object):
         else:
             log_object.update({'message': payload})
 
+        Validations.validate_log_message(log_object)
+
         log_object.update({
             'application_type': application_type,
             'dimensions': dimensions