MemoryBackend: init

nixops/plugin.py

@@ -2,8 +2,9 @@
 import nixops.plugins
 from nixops.storage import StorageBackend
 from nixops.storage.legacy import LegacyBackend
+from nixops.storage.memory import MemoryBackend
 
 
 @nixops.plugins.hookimpl
 def register_backends() -> Dict[str, Type[StorageBackend]]:
-    return {"legacy": LegacyBackend}
+    return {"legacy": LegacyBackend, "memory": MemoryBackend}

nixops/storage/memory.py

@@ -0,0 +1,27 @@
+import nixops.statefile
+from nixops.storage import StorageArgDescriptions, StorageArgValues
+
+
+class MemoryBackend:
+    @staticmethod
+    def arguments() -> StorageArgDescriptions:
+        raise NotImplementedError
+
+    def __init__(self, args: StorageArgValues) -> None:
+        pass
+
+    # fetchToFile: acquire a lock and download the state file to
+    # the local disk. Note: no arguments will be passed over kwargs.
+    # Making it part of the type definition allows adding new
+    # arguments later.
+    def fetchToFile(self, path: str, **kwargs) -> None:
+        pass
+
+    def onOpen(self, sf: nixops.statefile.StateFile, **kwargs) -> None:
+        sf.create_deployment()
+
+    # uploadFromFile: upload the new state file and release any locks
+    # Note: no arguments will be passed over kwargs. Making it part of
+    # the type definition allows adding new arguments later.
+    def uploadFromFile(self, path: str, **kwargs) -> None:
+        pass