Avoid instantiating config_layout in upper injector hierarchy

* Vm was grabbing a ConfigLayout as a dependency.

* Unfortunately, MacStore and KvStore were arranging for a ConfigLayout to be associated with base_injector.

* But carthage-runner was setting --keep on the layout injector not the base_injector

* So VMs were auto-shutting down

Fixes:

* VM explicitly gets an ConfigLayout from its injector rather than trusting dependency resolution

* MacStore and KvStore do the same to avoid polluting the base injector.

Thanks @timrcm for noticing that some VMs were disappearing.

carthage/kvstore.py

@@ -36,7 +36,7 @@
 
 __all__ += ['persistent_seed_path']
 
-@inject_autokwargs(config_layout=ConfigLayout,
+@inject_autokwargs(injector=Injector,
                    persistent_seed_path=InjectionKey(persistent_seed_path, _optional=True),
                    )
 class KvStore(Injectable):
@@ -45,6 +45,7 @@ def __init__(
             self, store_dir="persistent_assignments", max_size=4*2**30,
             **kwargs):
         super().__init__(**kwargs)
+        self.config_layout = self.injector(ConfigLayout)
         store_path = Path(store_dir)
         if not store_path.is_absolute():
             store_path = Path(self.config_layout.state_dir)/store_path

carthage/network/mac.py

@@ -27,7 +27,7 @@ def random_mac_addr():
 __all__ = ['random_mac_addr']
 
 
-@inject_autokwargs(config_layout=ConfigLayout,
+@inject_autokwargs(
                    injector=Injector,
                    kvstore=carthage.kvstore.KvStore)
 class MacStore(Injectable):
@@ -39,6 +39,7 @@ class MacStore(Injectable):
     def __init__(self, **kwargs):
         from .base import NetworkConfig
         super().__init__(**kwargs)
+        self.config_layout = self.injector(ConfigLayout)
         state_dir = Path(self.config_layout.state_dir)
         self.path = state_dir / "macs.yml"
         self.domain = self.kvstore.domain('mac', True)

carthage/vm.py

@@ -42,7 +42,6 @@
 
 
 @inject_autokwargs(
-    config_layout=ConfigLayout,
     injector=Injector,
     image=InjectionKey(vm_image_key, _ready=False),
     network_config=carthage.network.NetworkConfig
@@ -52,6 +51,7 @@ class VM(Machine, SetupTaskMixin):
     def __init__(self, name, *, console_needed=None,
                  **kwargs):
         super().__init__(name=name, **kwargs)
+        self.config_layout = self.injector(ConfigLayout)
         injector = self.injector
         config_layout = self.config_layout
         self.console_needed = console_needed