Add listener_runner to context object to enable developers to leverage lazy listeners in middleware

scripts/run_tests.sh

@@ -14,6 +14,5 @@ then
   black slack_bolt/ tests/ && \
     pytest -vv $1
 else
-    black slack_bolt/ tests/ && pytest
-  fi
+  black slack_bolt/ tests/ && pytest
 fi

slack_bolt/app/app.py

@@ -735,7 +735,7 @@ def step(
         elif not isinstance(step, WorkflowStep):
             raise BoltError(f"Invalid step object ({type(step)})")
 
-        self.use(WorkflowStepMiddleware(step, self.listener_runner))
+        self.use(WorkflowStepMiddleware(step))
 
     # -------------------------
     # global error handler
@@ -1350,6 +1350,10 @@ def _init_context(self, req: BoltRequest):
         )
         req.context["client"] = client_per_request
 
+        # Most apps do not need this "listener_runner" instance.
+        # It is intended for apps that start lazy listeners from their custom global middleware.
+        req.context["listener_runner"] = self.listener_runner
+
     @staticmethod
     def _to_listener_functions(
         kwargs: dict,

slack_bolt/app/async_app.py

@@ -761,7 +761,7 @@ def step(
         elif not isinstance(step, AsyncWorkflowStep):
             raise BoltError(f"Invalid step object ({type(step)})")
 
-        self.use(AsyncWorkflowStepMiddleware(step, self._async_listener_runner))
+        self.use(AsyncWorkflowStepMiddleware(step))
 
     # -------------------------
     # global error handler
@@ -1390,6 +1390,10 @@ def _init_context(self, req: AsyncBoltRequest):
         )
         req.context["client"] = client_per_request
 
+        # Most apps do not need this "listener_runner" instance.
+        # It is intended for apps that start lazy listeners from their custom global middleware.
+        req.context["listener_runner"] = self.listener_runner
+
     @staticmethod
     def _to_listener_functions(
         kwargs: dict,

slack_bolt/context/async_context.py

@@ -17,20 +17,29 @@ class AsyncBoltContext(BaseContext):
     def to_copyable(self) -> "AsyncBoltContext":
         new_dict = {}
         for prop_name, prop_value in self.items():
-            if prop_name in self.standard_property_names:
+            if prop_name in self.copyable_standard_property_names:
                 # all the standard properties are copiable
                 new_dict[prop_name] = prop_value
+            elif prop_name in self.non_copyable_standard_property_names:
+                # Do nothing with this property (e.g., listener_runner)
+                continue
             else:
                 try:
                     copied_value = create_copy(prop_value)
                     new_dict[prop_name] = copied_value
                 except TypeError as te:
                     self.logger.debug(
-                        f"Skipped settings '{prop_name}' to a copied request for lazy listeners "
+                        f"Skipped setting '{prop_name}' to a copied request for lazy listeners "
                         f"as it's not possible to make a deep copy (error: {te})"
                     )
         return AsyncBoltContext(new_dict)
 
+    # The return type is intentionally string to avoid circular imports
+    @property
+    def listener_runner(self) -> "AsyncioListenerRunner":  # type: ignore[name-defined]
+        """The properly configured listener_runner that is available for middleware/listeners."""
+        return self["listener_runner"]
+
     @property
     def client(self) -> Optional[AsyncWebClient]:
         """The `AsyncWebClient` instance available for this request.

slack_bolt/context/base_context.py

@@ -7,7 +7,7 @@
 class BaseContext(dict):
     """Context object associated with a request from Slack."""
 
-    standard_property_names = [
+    copyable_standard_property_names = [
         "logger",
         "token",
         "enterprise_id",
@@ -35,6 +35,11 @@ class BaseContext(dict):
         "complete",
         "fail",
     ]
+    non_copyable_standard_property_names = [
+        "listener_runner",
+    ]
+
+    standard_property_names = copyable_standard_property_names + non_copyable_standard_property_names
 
     @property
     def logger(self) -> Logger:

slack_bolt/context/context.py

@@ -17,9 +17,12 @@ class BoltContext(BaseContext):
     def to_copyable(self) -> "BoltContext":
         new_dict = {}
         for prop_name, prop_value in self.items():
-            if prop_name in self.standard_property_names:
+            if prop_name in self.copyable_standard_property_names:
                 # all the standard properties are copiable
                 new_dict[prop_name] = prop_value
+            elif prop_name in self.non_copyable_standard_property_names:
+                # Do nothing with this property (e.g., listener_runner)
+                continue
             else:
                 try:
                     copied_value = create_copy(prop_value)
@@ -32,6 +35,12 @@ def to_copyable(self) -> "BoltContext":
                     )
         return BoltContext(new_dict)
 
+    # The return type is intentionally string to avoid circular imports
+    @property
+    def listener_runner(self) -> "ThreadListenerRunner":  # type: ignore[name-defined]
+        """The properly configured listener_runner that is available for middleware/listeners."""
+        return self["listener_runner"]
+
     @property
     def client(self) -> Optional[WebClient]:
         """The `WebClient` instance available for this request.

slack_bolt/listener/asyncio_runner.py

@@ -174,12 +174,11 @@ def _start_lazy_function(self, lazy_func: Callable[..., Awaitable[None]], reques
         copied_request = self._build_lazy_request(request, func_name)
         self.lazy_listener_runner.start(function=lazy_func, request=copied_request)
 
-    @staticmethod
-    def _build_lazy_request(request: AsyncBoltRequest, lazy_func_name: str) -> AsyncBoltRequest:
-        copied_request = create_copy(request.to_copyable())
-        copied_request.method = "NONE"
+    def _build_lazy_request(self, request: AsyncBoltRequest, lazy_func_name: str) -> AsyncBoltRequest:
+        copied_request: AsyncBoltRequest = create_copy(request.to_copyable())
         copied_request.lazy_only = True
         copied_request.lazy_function_name = lazy_func_name
+        copied_request.context["listener_runner"] = self
         return copied_request
 
     def _debug_log_completion(self, starting_time: float, response: BoltResponse) -> None:

slack_bolt/listener/thread_runner.py

@@ -185,12 +185,11 @@ def _start_lazy_function(self, lazy_func: Callable[..., None], request: BoltRequ
         copied_request = self._build_lazy_request(request, func_name)
         self.lazy_listener_runner.start(function=lazy_func, request=copied_request)
 
-    @staticmethod
-    def _build_lazy_request(request: BoltRequest, lazy_func_name: str) -> BoltRequest:
-        copied_request = create_copy(request.to_copyable())
-        copied_request.method = "NONE"
+    def _build_lazy_request(self, request: BoltRequest, lazy_func_name: str) -> BoltRequest:
+        copied_request: BoltRequest = create_copy(request.to_copyable())
         copied_request.lazy_only = True
         copied_request.lazy_function_name = lazy_func_name
+        copied_request.context["listener_runner"] = self
         return copied_request
 
     def _debug_log_completion(self, starting_time: float, response: BoltResponse) -> None:

slack_bolt/workflows/step/async_step_middleware.py

@@ -2,7 +2,6 @@
 from typing import Callable, Optional, Awaitable
 
 from slack_bolt.listener.async_listener import AsyncListener
-from slack_bolt.listener.asyncio_runner import AsyncioListenerRunner
 from slack_bolt.middleware.async_middleware import AsyncMiddleware
 from slack_bolt.request.async_request import AsyncBoltRequest
 from slack_bolt.response import BoltResponse
@@ -13,9 +12,8 @@
 class AsyncWorkflowStepMiddleware(AsyncMiddleware):
     """Base middleware for step from app specific ones"""
 
-    def __init__(self, step: AsyncWorkflowStep, listener_runner: AsyncioListenerRunner):
+    def __init__(self, step: AsyncWorkflowStep):
         self.step = step
-        self.listener_runner = listener_runner
 
     async def async_process(
         self,
@@ -40,8 +38,8 @@ async def async_process(
 
         return await next()
 
+    @staticmethod
     async def _run(
-        self,
         listener: AsyncListener,
         req: AsyncBoltRequest,
         resp: BoltResponse,
@@ -50,7 +48,7 @@ async def _run(
         if next_was_not_called:
             return None
 
-        return await self.listener_runner.run(
+        return await req.context.listener_runner.run(
             request=req,
             response=resp,
             listener_name=get_name_for_callable(listener.ack_function),

slack_bolt/workflows/step/step_middleware.py

@@ -2,7 +2,6 @@
 from typing import Callable, Optional
 
 from slack_bolt.listener import Listener
-from slack_bolt.listener.thread_runner import ThreadListenerRunner
 from slack_bolt.middleware import Middleware
 from slack_bolt.request import BoltRequest
 from slack_bolt.response import BoltResponse
@@ -13,9 +12,8 @@
 class WorkflowStepMiddleware(Middleware):
     """Base middleware for step from app specific ones"""
 
-    def __init__(self, step: WorkflowStep, listener_runner: ThreadListenerRunner):
+    def __init__(self, step: WorkflowStep):
         self.step = step
-        self.listener_runner = listener_runner
 
     def process(
         self,
@@ -43,8 +41,8 @@ def process(
 
         return next()
 
+    @staticmethod
     def _run(
-        self,
         listener: Listener,
         req: BoltRequest,
         resp: BoltResponse,
@@ -53,7 +51,7 @@ def _run(
         if next_was_not_called:
             return None
 
-        return self.listener_runner.run(
+        return req.context.listener_runner.run(
             request=req,
             response=resp,
             listener_name=get_name_for_callable(listener.ack_function),

tests/scenario_tests/test_middleware.py

@@ -1,15 +1,23 @@
 import json
-from time import time
+import logging
+from time import time, sleep
+from typing import Callable, Optional
 
 from slack_sdk.signature import SignatureVerifier
 from slack_sdk.web import WebClient
 
+from slack_bolt import BoltResponse, CustomListenerMatcher
 from slack_bolt.app import App
+from slack_bolt.listener import CustomListener
+from slack_bolt.listener.thread_runner import ThreadListenerRunner
+from slack_bolt.middleware import Middleware
 from slack_bolt.request import BoltRequest
+from slack_bolt.request.payload_utils import is_shortcut
 from tests.mock_web_api_server import (
     setup_mock_web_api_server,
     cleanup_mock_web_api_server,
     assert_auth_test_count,
+    assert_received_request_count,
 )
 from tests.utils import remove_os_env_temporarily, restore_os_env
 
@@ -168,6 +176,27 @@ def __call__(self, next_):
         assert response.body == "acknowledged!"
         assert_auth_test_count(self, 1)
 
+    def test_lazy_listener_middleware(self):
+        app = App(
+            client=self.web_client,
+            signing_secret=self.signing_secret,
+        )
+        unmatch_middleware = LazyListenerStarter("xxxx")
+        app.use(unmatch_middleware)
+
+        response = app.dispatch(self.build_request())
+        assert response.status == 404
+        assert_auth_test_count(self, 1)
+
+        my_middleware = LazyListenerStarter("test-shortcut")
+        app.use(my_middleware)
+        response = app.dispatch(self.build_request())
+        assert response.status == 200
+        count = 0
+        while count < 20 and my_middleware.lazy_called is False:
+            sleep(0.05)
+        assert my_middleware.lazy_called is True
+
 
 def just_ack(ack):
     ack("acknowledged!")
@@ -183,3 +212,42 @@ def just_next(next):
 
 def just_next_(next_):
     next_()
+
+
+class LazyListenerStarter(Middleware):
+    lazy_called: bool
+    callback_id: str
+
+    def __init__(self, callback_id: str):
+        self.lazy_called = False
+        self.callback_id = callback_id
+
+    def lazy_listener(self):
+        self.lazy_called = True
+
+    def process(self, *, req: BoltRequest, resp: BoltResponse, next: Callable[[], BoltResponse]) -> Optional[BoltResponse]:
+        if is_shortcut(req.body):
+            listener = CustomListener(
+                app_name="test-app",
+                ack_function=just_ack,
+                lazy_functions=[self.lazy_listener],
+                matchers=[
+                    CustomListenerMatcher(
+                        app_name="test-app",
+                        func=lambda payload: payload.get("callback_id") == self.callback_id,
+                    )
+                ],
+                middleware=[],
+                base_logger=req.context.logger,
+            )
+            if listener.matches(req=req, resp=resp):
+                listener_runner: ThreadListenerRunner = req.context.listener_runner
+                response = listener_runner.run(
+                    request=req,
+                    response=resp,
+                    listener_name="test",
+                    listener=listener,
+                )
+                if response is not None:
+                    return response
+        next()