Scaling down removes containers

Squashed version of #162.
Closes #121.

fig/cli/main.py

@@ -298,20 +298,13 @@ class TopLevelCommand(Command):
         """
         detached = options['-d']
 
-        (old, new) = self.project.recreate_containers(service_names=options['SERVICE'])
+        new = self.project.up(service_names=options['SERVICE'])
 
         if not detached:
             to_attach = [c for (s, c) in new]
             print("Attaching to", list_containers(to_attach))
             log_printer = LogPrinter(to_attach, attach_params={"logs": True})
 
-        for (service, container) in new:
-            service.start_container(container)
-
-        for (service, container) in old:
-            container.remove()
-
-        if not detached:
             try:
                 log_printer.run()
             finally:

fig/project.py

@@ -137,6 +137,17 @@ class Project(object):
             else:
                 log.info('%s uses an image, skipping' % service.name)
 
+    def up(self, service_names=None):
+        (old, new) = self.recreate_containers(service_names=service_names)
+
+        for (service, container) in new:
+            service.start_container(container)
+
+        for (service, container) in old:
+            container.remove()
+
+        return new
+
     def remove_stopped(self, service_names=None, **options):
         for service in self.get_services(service_names):
             service.remove_stopped(**options)

fig/service.py

@@ -85,6 +85,14 @@ class Service(object):
             c.kill(**options)
 
     def scale(self, desired_num):
+        """
+        Adjusts the number of containers to the specified number and ensures they are running.
+
+        - creates containers until there are at least `desired_num`
+        - stops containers until there are at most `desired_num` running
+        - starts containers until there are at least `desired_num` running
+        - removes all stopped containers
+        """
         if not self.can_be_scaled():
             raise CannotBeScaledError()
 
@@ -117,6 +125,8 @@ class Service(object):
             self.start_container(c)
             running_containers.append(c)
 
+        self.remove_stopped()
+
 
     def remove_stopped(self, **options):
         for c in self.containers(stopped=True):