Fix and document `dns:` option

Closes #240.

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

docs/yml.md

@@ -118,3 +118,14 @@ net: "none"
 net: "container:[name or id]"
 net: "host"
 ```
+
+### dns
+
+Custom DNS servers. Can be a single value or a list.
+
+```
+dns: 8.8.8.8
+dns:
+  - 8.8.8.8
+  - 9.9.9.9
+```

fig/service.py

@@ -239,6 +239,7 @@ class Service(object):
 
         privileged = options.get('privileged', False)
         net = options.get('net', 'bridge')
+        dns = options.get('dns', None)
 
         container.start(
             links=self._get_links(link_to_self=override_options.get('one_off', False)),
@@ -247,6 +248,7 @@ class Service(object):
             volumes_from=self._get_volumes_from(intermediate_container),
             privileged=privileged,
             network_mode=net,
+            dns=dns,
         )
         return container
 
@@ -347,13 +349,10 @@ class Service(object):
                 self.build()
             container_options['image'] = self._build_tag_name()
 
-        # Priviliged is only required for starting containers, not for creating them
-        if 'privileged' in container_options:
-            del container_options['privileged']
-
-        # net is only required for starting containers, not for creating them
-        if 'net' in container_options:
-            del container_options['net']
+        # Delete options which are only used when starting
+        for key in ['privileged', 'net', 'dns']:
+            if key in container_options:
+                del container_options[key]
 
         return container_options
 

tests/integration/service_test.py

@@ -316,6 +316,16 @@ class ServiceTest(DockerClientTestCase):
         container = service.start_container().inspect()
         self.assertEqual(container['HostConfig']['NetworkMode'], 'host')
 
+    def test_dns_single_value(self):
+        service = self.create_service('web', dns='8.8.8.8')
+        container = service.start_container().inspect()
+        self.assertEqual(container['HostConfig']['Dns'], ['8.8.8.8'])
+
+    def test_dns_list(self):
+        service = self.create_service('web', dns=['8.8.8.8', '9.9.9.9'])
+        container = service.start_container().inspect()
+        self.assertEqual(container['HostConfig']['Dns'], ['8.8.8.8', '9.9.9.9'])
+
     def test_working_dir_param(self):
         service = self.create_service('container', working_dir='/working/dir/sample')
         container = service.create_container().inspect()