Add an acceptance test and docs for the down subcommand

Signed-off-by: Daniel Nephin <dnephin@docker.com>

compose/cli/main.py

@@ -247,7 +247,7 @@ class TopLevelCommand(DocoptCommand):
     def down(self, project, options):
         """
         Stop containers and remove containers, networks, volumes, and images
-        created by `up`.
+        created by `up`. Only containers and networks are removed by default.
 
         Usage: down [options]
 

compose/parallel.py

@@ -24,7 +24,7 @@ def parallel_execute(objects, func, index_func, msg):
     object we give it.
     """
     objects = list(objects)
-    stream = get_output_stream(sys.stdout)
+    stream = get_output_stream(sys.stderr)
     writer = ParallelStreamWriter(stream, msg)
 
     for obj in objects:

compose/project.py

@@ -272,7 +272,7 @@ class Project(object):
 
     def down(self, remove_image_type, include_volumes):
         self.stop()
-        self.remove_stopped()
+        self.remove_stopped(v=include_volumes)
         self.remove_network()
 
         if include_volumes:
@@ -441,6 +441,7 @@ class Project(object):
             return
         network = self.get_network()
         if network:
+            log.info("Removing network %s", self.default_network_name)
             self.client.remove_network(network['Id'])
 
     def uses_default_network(self):

compose/service.py

@@ -686,6 +686,7 @@ class Service(object):
         if image_type == ImageType.local and self.options.get('image'):
             return False
 
+        log.info("Removing image %s", self.image_name)
         try:
             self.client.remove_image(self.image_name)
             return True

compose/volume.py

@@ -1,9 +1,14 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+import logging
+
 from docker.errors import NotFound
 
 
+log = logging.getLogger(__name__)
+
+
 class Volume(object):
     def __init__(self, client, project, name, driver=None, driver_opts=None,
                  external_name=None):
@@ -20,6 +25,10 @@ class Volume(object):
         )
 
     def remove(self):
+        if self.external:
+            log.info("Volume %s is external, skipping", self.full_name)
+            return
+        log.info("Removing volume %s", self.full_name)
         return self.client.remove_volume(self.full_name)
 
     def inspect(self):