Add deferrable param in FileSensor

airflow/sensors/filesystem.py

@@ -19,11 +19,15 @@
 
 import datetime
 import os
+from functools import cached_property
 from glob import glob
 from typing import TYPE_CHECKING, Sequence
 
+from airflow.configuration import conf
+from airflow.exceptions import AirflowException
 from airflow.hooks.filesystem import FSHook
 from airflow.sensors.base import BaseSensorOperator
+from airflow.triggers.file import FileTrigger
 
 if TYPE_CHECKING:
     from airflow.utils.context import Context
@@ -42,6 +46,8 @@ class FileSensor(BaseSensorOperator):
         the base path set within the connection), can be a glob.
     :param recursive: when set to ``True``, enables recursive directory matching behavior of
         ``**`` in glob filepath parameter. Defaults to ``False``.
+    :param deferrable: If waiting for completion, whether to defer the task until done,
+        default is ``False``.
 
     .. seealso::
         For more information on how to use this sensor, take a look at the guide:
@@ -53,19 +59,31 @@ class FileSensor(BaseSensorOperator):
     template_fields: Sequence[str] = ("filepath",)
     ui_color = "#91818a"
 
-    def __init__(self, *, filepath, fs_conn_id="fs_default", recursive=False, **kwargs):
+    def __init__(
+        self,
+        *,
+        filepath,
+        fs_conn_id="fs_default",
+        recursive=False,
+        deferrable: bool = conf.getboolean("operators", "default_deferrable", fallback=False),
+        **kwargs,
+    ):
         super().__init__(**kwargs)
         self.filepath = filepath
         self.fs_conn_id = fs_conn_id
         self.recursive = recursive
+        self.deferrable = deferrable
 
-    def poke(self, context: Context):
+    @cached_property
+    def path(self) -> str:
         hook = FSHook(self.fs_conn_id)
         basepath = hook.get_path()
         full_path = os.path.join(basepath, self.filepath)
-        self.log.info("Poking for file %s", full_path)
+        return full_path
 
-        for path in glob(full_path, recursive=self.recursive):
+    def poke(self, context: Context) -> bool:
+        self.log.info("Poking for file %s", self.path)
+        for path in glob(self.path, recursive=self.recursive):
             if os.path.isfile(path):
                 mod_time = datetime.datetime.fromtimestamp(os.path.getmtime(path)).strftime("%Y%m%d%H%M%S")
                 self.log.info("Found File %s last modified: %s", path, mod_time)
@@ -75,3 +93,22 @@ def poke(self, context: Context):
                 if files:
                     return True
         return False
+
+    def execute(self, context: Context) -> None:
+        if not self.deferrable:
+            super().execute(context=context)
+        if not self.poke(context=context):
+            self.defer(
+                timeout=datetime.timedelta(seconds=self.timeout),
+                trigger=FileTrigger(
+                    filepath=self.path,
+                    recursive=self.recursive,
+                    poke_interval=self.poke_interval,
+                ),
+                method_name="execute_complete",
+            )
+
+    def execute_complete(self, context: Context, event: bool | None = None) -> None:
+        if not event:
+            raise AirflowException("%s task failed as %s not found.", self.task_id, self.filepath)
+        self.log.info("%s completed successfully as %s found.", self.task_id, self.filepath)

airflow/triggers/file.py

@@ -20,6 +20,7 @@
 import datetime
 import os
 import typing
+import warnings
 from glob import glob
 from typing import Any
 
@@ -34,18 +35,29 @@ class FileTrigger(BaseTrigger):
         be a glob.
     :param recursive: when set to ``True``, enables recursive directory matching behavior of
         ``**`` in glob filepath parameter. Defaults to ``False``.
+    :param poke_interval: Time that the job should wait in between each try
     """
 
     def __init__(
         self,
         filepath: str,
         recursive: bool = False,
-        poll_interval: float = 5.0,
+        poke_interval: float = 5.0,
+        **kwargs,
     ):
         super().__init__()
         self.filepath = filepath
         self.recursive = recursive
-        self.poll_interval = poll_interval
+        if kwargs.get("poll_interval") is not None:
+            warnings.warn(
+                "`poll_interval` has been deprecated and will be removed in future."
+                "Please use `poke_interval` instead.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            self.poke_interval: float = kwargs["poll_interval"]
+        else:
+            self.poke_interval = poke_interval
 
     def serialize(self) -> tuple[str, dict[str, Any]]:
         """Serialize FileTrigger arguments and classpath."""
@@ -54,7 +66,7 @@ def serialize(self) -> tuple[str, dict[str, Any]]:
             {
                 "filepath": self.filepath,
                 "recursive": self.recursive,
-                "poll_interval": self.poll_interval,
+                "poke_interval": self.poke_interval,
             },
         )
 
@@ -70,4 +82,4 @@ async def run(self) -> typing.AsyncIterator[TriggerEvent]:
                 for _, _, files in os.walk(self.filepath):
                     if files:
                         yield TriggerEvent(True)
-            await asyncio.sleep(self.poll_interval)
+            await asyncio.sleep(self.poke_interval)

tests/sensors/test_filesystem.py

@@ -23,9 +23,10 @@
 
 import pytest
 
-from airflow.exceptions import AirflowSensorTimeout
+from airflow.exceptions import AirflowSensorTimeout, TaskDeferred
 from airflow.models.dag import DAG
 from airflow.sensors.filesystem import FileSensor
+from airflow.triggers.file import FileTrigger
 from airflow.utils.timezone import datetime
 
 pytestmark = pytest.mark.db_test
@@ -219,3 +220,17 @@ def test_subdirectory_empty(self):
         with pytest.raises(AirflowSensorTimeout):
             task.run(start_date=DEFAULT_DATE, end_date=DEFAULT_DATE, ignore_ti_state=True)
             shutil.rmtree(temp_dir)
+
+    def test_task_defer(self):
+        task = FileSensor(
+            task_id="test",
+            filepath="temp_dir",
+            fs_conn_id="fs_default",
+            deferrable=True,
+            dag=self.dag,
+        )
+
+        with pytest.raises(TaskDeferred) as exc:
+            task.execute(None)
+
+        assert isinstance(exc.value.trigger, FileTrigger), "Trigger is not a FileTrigger"

tests/triggers/test_file.py

@@ -33,7 +33,7 @@ def test_serialization(self):
         assert classpath == "airflow.triggers.file.FileTrigger"
         assert kwargs == {
             "filepath": self.FILE_PATH,
-            "poll_interval": 5,
+            "poke_interval": 5,
             "recursive": False,
         }