Add new --pull option in build.

Signed-off-by: Christophe Labouisse <christophe@labouisse.org>

compose/cli/main.py

@@ -153,9 +153,11 @@ class TopLevelCommand(Command):
 
         Options:
             --no-cache  Do not use cache when building the image.
+            --pull      Always attempt to pull a newer version of the image.
         """
         no_cache = bool(options.get('--no-cache', False))
-        project.build(service_names=options['SERVICE'], no_cache=no_cache)
+        pull = bool(options.get('--pull', False))
+        project.build(service_names=options['SERVICE'], no_cache=no_cache, pull=pull)
 
     def help(self, project, options):
         """

compose/project.py

@@ -257,10 +257,10 @@ class Project(object):
         for service in self.get_services(service_names):
             service.restart(**options)
 
-    def build(self, service_names=None, no_cache=False):
+    def build(self, service_names=None, no_cache=False, pull=False):
         for service in self.get_services(service_names):
             if service.can_be_built():
-                service.build(no_cache)
+                service.build(no_cache, pull)
             else:
                 log.info('%s uses an image, skipping' % service.name)
 

compose/service.py

@@ -700,7 +700,7 @@ class Service(object):
             security_opt=security_opt
         )
 
-    def build(self, no_cache=False):
+    def build(self, no_cache=False, pull=False):
         log.info('Building %s' % self.name)
 
         path = self.options['build']
@@ -714,7 +714,7 @@ class Service(object):
             tag=self.image_name,
             stream=True,
             rm=True,
-            pull=False,
+            pull=pull,
             nocache=no_cache,
             dockerfile=self.options.get('dockerfile', None),
         )