Add Model.connect() for connecting to arbitrary endpoint

[osm/N2VC.git] / juju / model.py

diff --git a/juju/model.py b/juju/model.py
index 8a49495..5ca7422 100644 (file)
--- a/juju/model.py
+++ b/juju/model.py
@@ -159,14 +159,12 @@ class ModelState(object):
 
     def get_entity(
             self, entity_type, entity_id, history_index=-1, connected=True):
-        """Return an object instance representing the entity created or
-        updated by ``delta``
+        """Return an object instance for the given entity_type and id.
+
+        By default the object state matches the most recent state from
+        Juju. To get an instance of the object in an older state, pass
+        history_index, an index into the history deque for the entity.
 
-        """
-        """
-        log.debug(
-            'Getting %s:%s at index %s',
-            entity_type, entity_id, history_index)
         """
 
         if history_index < 0 and history_index != -1:
@@ -351,6 +349,16 @@ class Model(object):
         self._watch_received = asyncio.Event(loop=loop)
         self._charmstore = CharmStore(self.loop)
 
+    async def connect(self, *args, **kw):
+        """Connect to an arbitrary Juju model.
+
+        args and kw are passed through to Connection.connect()
+
+        """
+        self.connection = await connection.Connection.connect(*args, **kw)
+        self._watch()
+        await self._watch_received.wait()
+
     async def connect_current(self):
         """Connect to the current Juju model.
 
@@ -535,6 +543,30 @@ class Model(object):
             if o.cares_about(delta):
                 asyncio.ensure_future(o(delta, old_obj, new_obj, self))
 
+    async def _wait(self, entity_type, entity_id, action, predicate=None):
+        """
+        Block the calling routine until a given action has happened to the
+        given entity
+
+        :param entity_type: The entity's type.
+        :param entity_id: The entity's id.
+        :param action: the type of action (e.g., 'add' or 'change')
+        :param predicate: optional callable that must take as an
+            argument a delta, and must return a boolean, indicating
+            whether the delta contains the specific action we're looking
+            for. For example, you might check to see whether a 'change'
+            has a 'completed' status. See the _Observer class for details.
+
+        """
+        q = asyncio.Queue(loop=self.loop)
+
+        async def callback(delta, old, new, model):
+            await q.put(delta.get_id())
+
+        self.add_observer(callback, entity_type, action, entity_id, predicate)
+        entity_id = await q.get()
+        return self.state._live_entity_map(entity_type)[entity_id]
+
     async def _wait_for_new(self, entity_type, entity_id, predicate=None):
         """Wait for a new object to appear in the Model and return it.
 
@@ -543,14 +575,20 @@ class Model(object):
         This coroutine blocks until the new object appears in the model.
 
         """
-        entity_added = asyncio.Queue(loop=self.loop)
+        return await self._wait(entity_type, entity_id, 'add', predicate)
 
-        async def callback(delta, old, new, model):
-            await entity_added.put(delta.get_id())
+    async def wait_for_action(self, action_id):
+        """Given an action, wait for it to complete."""
 
-        self.add_observer(callback, entity_type, 'add', entity_id, predicate)
-        entity_id = await entity_added.get()
-        return self.state._live_entity_map(entity_type)[entity_id]
+        if action_id.startswith("action-"):
+            # if we've been passed action.tag, transform it into the
+            # id that the api deltas will use.
+            action_id = action_id[7:]
+
+        def predicate(delta):
+            return delta.data['status'] in ('completed', 'failed')
+
+        return await self._wait('action', action_id, 'change', predicate)
 
     def add_machine(
             self, spec=None, constraints=None, disks=None, series=None,
@@ -759,9 +797,6 @@ class Model(object):
             - series is required; how do we pick a default?
 
         """
-        if constraints:
-            constraints = client.Value(**constraints)
-
         if to:
             placement = [
                 client.Placement(**p) for p in to
@@ -818,7 +853,7 @@ class Model(object):
             )
 
             await app_facade.Deploy([app])
-            return [await self._wait_for_new('application', service_name)]
+            return await self._wait_for_new('application', service_name)
 
     def destroy(self):
         """Terminate all machines and resources for this model.