Add DockerCommand driver

Introduces a new snapshot driver that is
the same as Command driver but prepends
'docker exec ' to each command in the
object.

Change-Id: I8bf939bdb5a489982bc38257a245b4233103a07a
Related-Bug: #1515517

shotgun/driver.py

@@ -57,6 +57,7 @@ class Driver(object):
             "postgres": Postgres,
             "xmlrpc": XmlRpc,
             "command": Command,
+            "docker_command": DockerCommand,
             "offline": Offline,
         }.get(driver_type, cls)(data, conf)
 
@@ -293,6 +294,16 @@ class Command(Driver):
                 f.write(out.stderr)
 
 
+class DockerCommand(Command):
+    def __init__(self, data, conf):
+        super(DockerCommand, self).__init__(data, conf)
+        self.cmds = [
+            "docker exec "
+            "$(docker ps -q --filter 'name={0}' --format '{{.Names}}') "
+            "{1}".format(cnt, cmd)
+            for cnt in data["containers"] for cmd in self.cmds]
+
+
 class Offline(Driver):
 
     def __init__(self, data, conf):

shotgun/test/test_driver.py

@@ -332,6 +332,29 @@ class TestCommand(base.BaseTestCase):
                              file_handle_mock.write.call_args_list)
 
 
+class TestDockerCommand(base.BaseTestCase):
+    def setUp(self):
+        self.conf = mock.Mock()
+        self.conf.target = '/some/dir'
+
+    def test_init(self):
+        data = {
+            "command": ["cmd1", "cmd2"],
+            "containers": ["cont1", "cont2"],
+        }
+        driver_inst = shotgun.driver.DockerCommand(data, self.conf)
+        template_str = (
+            "docker exec "
+            "$(docker ps -q --filter 'name={0}' --format '{{.Names}}') {1}")
+        expected = [
+            template_str.format("cont1", "cmd1"),
+            template_str.format("cont1", "cmd2"),
+            template_str.format("cont2", "cmd1"),
+            template_str.format("cont2", "cmd2"),
+        ]
+        self.assertListEqual(expected, driver_inst.cmds)
+
+
 class TestOffline(base.BaseTestCase):
 
     @mock.patch('shotgun.driver.open', create=True,