Issue/6025 implement top level handler abc

src/inmanta/agent/handler.py

@@ -55,7 +55,7 @@ class provider(object):  # noqa: N801
     """
     A decorator that registers a new handler.
 
-    :param resource_type: The type of the resource this handler provides an implementation for.
+    :param resource_type: The type of the resource this handler is responsible for.
                           For example, :inmanta:entity:`std::File`
     :param name: A name to reference this provider.
     """
@@ -419,7 +419,52 @@ def _log_msg(self, level: int, msg: str, *args: object, exc_info: bool = False,
 
 
 @stable_api
-class ResourceHandler(object):
+class HandlerABC(ABC):
+    """
+    Top-level abstract base class all handlers should inherit from.
+    """
+
+    @abstractmethod
+    def pre(self, ctx: HandlerContext, resource: resources.Resource) -> None:
+        """
+        Method executed before a handler operation (Facts, dryrun, real deployment, ...) is executed. Override this method
+        to run before an operation.
+
+        :param ctx: Context object to report changes and logs to the agent and server.
+        :param resource: The resource to query facts for.
+        """
+
+    @abstractmethod
+    def post(self, ctx: HandlerContext, resource: resources.Resource) -> None:
+        """
+        Method executed after an operation. Override this method to run after an operation.
+
+        :param ctx: Context object to report changes and logs to the agent and server.
+        :param resource: The resource to query facts for.
+        """
+
+    @abstractmethod
+    def deploy(
+        self,
+        ctx: HandlerContext,
+        resource: resources.Resource,
+        requires: Dict[ResourceIdStr, ResourceState],
+    ) -> None:
+        """
+        This method is always called by the agent
+        """
+        pass
+
+    @abstractmethod
+    def execute(self, ctx: HandlerContext, resource: resources.Resource, dry_run: Optional[bool] = None) -> None:
+        """
+        Update the given resource. This method is called by the agent.
+        """
+        pass
+
+
+@stable_api
+class ResourceHandler(HandlerABC):
     """
     A baseclass for classes that handle resources. New handler are registered with the
     :func:`~inmanta.agent.handler.provider` decorator.
@@ -499,23 +544,6 @@ def do_reload(self, ctx: HandlerContext, resource: resources.Resource) -> None:
         :param resource: The resource to reload.
         """
 
-    def pre(self, ctx: HandlerContext, resource: resources.Resource) -> None:
-        """
-        Method executed before a handler operation (Facts, dryrun, real deployment, ...) is executed. Override this method
-        to run before an operation.
-
-        :param ctx: Context object to report changes and logs to the agent and server.
-        :param resource: The resource to query facts for.
-        """
-
-    def post(self, ctx: HandlerContext, resource: resources.Resource) -> None:
-        """
-        Method executed after an operation. Override this method to run after an operation.
-
-        :param ctx: Context object to report changes and logs to the agent and server.
-        :param resource: The resource to query facts for.
-        """
-
     def close(self) -> None:
         pass
 
@@ -582,7 +610,7 @@ def deploy(
         requires: Dict[ResourceIdStr, ResourceState],
     ) -> None:
         """
-        This method is always be called by the agent, even when one of the requires of the given resource
+        This method is always called by the agent, even when one of the requires of the given resource
         failed to deploy. The default implementation of this method will deploy the given resource when all its
         requires were deployed successfully. Override this method if a different condition determines whether the
         resource should deploy.