Initial Deployable support for Libvirt

* Include the layout_name and orphan_policy in  metadata associated with VMs so we can build an orhpan finder.

* Add find, find_or_create to Vm.

Currently the find method has the wrong semantics. We want to consider a VM existing when its volume exists, but that requires reworking ImageVolume. So for now only running VMs exist as Deployables.

carthage/image.py

@@ -250,7 +250,7 @@ class ImageVolume(AsyncInjectable, SetupTaskMixin):
 
     '''
     Represents a raw disk image.
-    Can be unpacked from a compressed base image, or created by a callback (or eros if *unpack* is False).
+    Can be unpacked from a compressed base image, or created by a callback (or zeros if *unpack* is False).
     If *base_image* is set, then ``cp --reflink`` is used to clone an image.
 
     '''

carthage/resources/templates/vm-config.mako

@@ -20,6 +20,9 @@ def is_vnc():
 <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
   <name>${name}</name>
   <uuid>${uuid}</uuid>
+  <metadata>
+    <carthage:layout xmlns:carthage='https://github.com/hadron/carthage' layout='${layout_name}' orphan_policy='${orphan_policy}'/>
+    </metadata>
   <memory unit='KiB'>${memory_mb*1024}</memory>
 
   <vcpu placement='static' >${cpus}</vcpu>

carthage/vm.py

@@ -19,6 +19,7 @@
 import mako.template
 from pathlib import Path
 from .dependency_injection import *
+from . import deployment
 from .utils import when_needed, memoproperty
 from .setup_tasks import SetupTaskMixin, setup_task
 from .image import  ImageVolume
@@ -81,14 +82,36 @@ async def gen_volume(self):
         self.ssh_rekeyed()
         os.makedirs(self.stamp_path, exist_ok=True)
 
+    async def find(self):
+        if self.domid():
+            return True
+        return False
+
+    async def find_or_create(self):
+        if await self.find():
+            return
+        await self.start_machine()
+
     async def write_config(self):
+        from .modeling import CarthageLayout
         template = _templates.get_template("vm-config.mako")
         await self.resolve_networking()
         for i, link in self.network_links.items():
             await link.instantiate(carthage.network.BridgeNetwork)
         if self.image:
             await self.image.async_become_ready()
         await self.gen_volume()
+        layout = await self.ainjector.get_instance_async(InjectionKey(CarthageLayout, _ready=False, _optional=True))
+        if layout:
+            layout_name = layout.layout_name
+            try:
+                orphan_policy = layout.injector.get_instance(deployment.orphan_policy)
+            except KeyError:
+                orphan_policy = deployment.DeletionPolicy.delete
+        else:
+            layout_name = ''
+            orphan_policy  = deployment.DeletionPolicy.retain
+
         ci_data = None
         if self.model and getattr(self.model, 'cloud_init', False):
             ci_data = await self.ainjector(carthage.cloud_init.generate_cloud_init_cidata)
@@ -103,6 +126,8 @@ async def write_config(self):
                 console_needed=console_needed,
                 console_port=self.console_port.port if self.console_needed else None,
                 name=self.full_name,
+                layout_name=layout_name,
+                orphan_policy=orphan_policy,
                 links=self.network_links,
                 model_in=self.model,
                 disk_config=disk_config,
@@ -440,3 +465,5 @@ async def unpack(self):
 
 
         __all__ = ('VM', 'Vm', 'InstallQemuAgent')
+
+