Add container.get() which removes the duplication of container.inspect() in every property, and provides a nicer interface for querying container data.

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

fig/container.py

@@ -67,7 +67,7 @@ class Container(object):
     @property
     def ports(self):
         self.inspect_if_not_inspected()
-        return self.dictionary['NetworkSettings']['Ports'] or {}
+        return self.get('NetworkSettings.Ports') or {}
 
     @property
     def human_readable_ports(self):
@@ -82,33 +82,35 @@ class Container(object):
 
     @property
     def human_readable_state(self):
-        self.inspect_if_not_inspected()
-        if self.dictionary['State']['Running']:
-            if self.dictionary['State'].get('Ghost'):
-                return 'Ghost'
-            else:
-                return 'Up'
+        if self.is_running:
+            return 'Ghost' if self.get('State.Ghost') else 'Up'
         else:
-            return 'Exit %s' % self.dictionary['State']['ExitCode']
+            return 'Exit %s' % self.get('State.ExitCode')
 
     @property
     def human_readable_command(self):
-        self.inspect_if_not_inspected()
-        if self.dictionary['Config']['Cmd']:
-            return ' '.join(self.dictionary['Config']['Cmd'])
-        else:
-            return ''
+        return ' '.join(self.get('Config.Cmd') or '')
 
     @property
     def environment(self):
-        self.inspect_if_not_inspected()
-        return dict(var.split("=", 1)
-                    for var in self.dictionary.get('Config', {}).get('Env', []))
+        return dict(var.split("=", 1) for var in self.get('Config.Env') or [])
 
     @property
     def is_running(self):
+        return self.get('State.Running')
+
+    def get(self, key):
+        """Return a value from the container or None if the value is not set.
+
+        :param key: a string using dotted notation for nested dictionary
+                    lookups
+        """
         self.inspect_if_not_inspected()
-        return self.dictionary['State']['Running']
+
+        def get_value(dictionary, key):
+            return (dictionary or {}).get(key)
+
+        return reduce(get_value, key.split('.'), self.dictionary)
 
     def get_local_port(self, port, protocol='tcp'):
         port = self.ports.get("%s/%s" % (port, protocol))

tests/unit/container_test.py

@@ -105,3 +105,15 @@ class ContainerTest(unittest.TestCase):
         self.assertEqual(
             container.get_local_port(45454, protocol='tcp'),
             '0.0.0.0:49197')
+
+    def test_get(self):
+        container = Container(None, {
+            "Status":"Up 8 seconds",
+            "HostConfig": {
+                "VolumesFrom": ["volume_id",]
+            },
+        }, has_been_inspected=True)
+
+        self.assertEqual(container.get('Status'), "Up 8 seconds")
+        self.assertEqual(container.get('HostConfig.VolumesFrom'), ["volume_id",])
+        self.assertEqual(container.get('Foo.Bar.DoesNotExist'), None)