SDK-354 Default to S3 Signature Version V4 (#273)

Signature Version V2 will be deprecated by AWS which was the default for boto, configured it to use v4 signature for s3 authentication.

qds_sdk/commands.py

@@ -299,19 +299,17 @@ def get_results(self, fp=sys.stdout, inline=True, delim=None, fetch=True, qlog=N
                     pass
         else:
             if fetch:
+                if not boto.config.has_section('s3'):
+                    boto.config.add_section('s3')
+                boto.config.set('s3', 'use-sigv4', 'True')
                 storage_credentials = conn.get(Account.credentials_rest_entity_path)
-                if storage_credentials['region_endpoint'] is not None:
-                    boto_conn = boto.connect_s3(aws_access_key_id=storage_credentials['storage_access_key'],
-                                                aws_secret_access_key=storage_credentials['storage_secret_key'],
-                                                security_token = storage_credentials['session_token'],
-                                                host = storage_credentials['region_endpoint'])
-                else:
-                    boto_conn = boto.connect_s3(aws_access_key_id=storage_credentials['storage_access_key'],
-                                                aws_secret_access_key=storage_credentials['storage_secret_key'],
-                                                security_token=storage_credentials['session_token'])
-
+                host = storage_credentials['region_endpoint'] if storage_credentials['region_endpoint'] else "s3.amazonaws.com"
+                boto_conn = boto.connect_s3(aws_access_key_id=storage_credentials['storage_access_key'],
+                                            aws_secret_access_key=storage_credentials['storage_secret_key'],
+                                            security_token=storage_credentials['session_token'],
+                                            host=host)
                 log.info("Starting download from result locations: [%s]" % ",".join(r['result_location']))
-                #fetch latest value of num_result_dir
+                # fetch latest value of num_result_dir
                 num_result_dir = Command.find(self.id).num_result_dir
 
                 # If column/header names are not able to fetch then use include header as true