Update to address code review feedback

Signed-off-by: Evan Shaw <evan@vendhq.com>

compose/cli/main.py

@@ -607,7 +607,7 @@ class TopLevelCommand(object):
         self.project.pull(
             service_names=options['SERVICE'],
             ignore_pull_failures=options.get('--ignore-pull-failures'),
-            in_parallel=options.get('--parallel')
+            parallel_pull=options.get('--parallel')
         )
 
     def push(self, options):

compose/project.py

@@ -454,10 +454,10 @@ class Project(object):
 
         return plans
 
-    def pull(self, service_names=None, ignore_pull_failures=False, in_parallel=False):
+    def pull(self, service_names=None, ignore_pull_failures=False, parallel_pull=False):
         services = self.get_services(service_names, include_deps=False)
 
-        if in_parallel:
+        if parallel_pull:
             def pull_service(service):
                 service.pull(ignore_pull_failures, True)
 

compose/service.py

@@ -2,6 +2,7 @@ from __future__ import absolute_import
 from __future__ import unicode_literals
 
 import logging
+import os
 import re
 import sys
 from collections import namedtuple
@@ -896,7 +897,11 @@ class Service(object):
             log.info('Pulling %s (%s%s%s)...' % (self.name, repo, separator, tag))
         try:
             output = self.client.pull(repo, tag=tag, stream=True)
-            if not silent:
+            if silent:
+                with open(os.devnull, 'w') as devnull:
+                    return progress_stream.get_digest_from_pull(
+                        stream_output(output, devnull))
+            else:
                 return progress_stream.get_digest_from_pull(
                     stream_output(output, sys.stdout))
         except (StreamOutputError, NotFound) as e: