Improve typing in prefect.server.events (#16692)

src/prefect/_internal/retries.py

@@ -29,7 +29,7 @@ def retry_async_fn(
     retry_on_exceptions: tuple[type[Exception], ...] = (Exception,),
     operation_name: Optional[str] = None,
 ) -> Callable[
-    [Callable[P, Coroutine[Any, Any, R]]], Callable[P, Coroutine[Any, Any, Optional[R]]]
+    [Callable[P, Coroutine[Any, Any, R]]], Callable[P, Coroutine[Any, Any, R]]
 ]:
     """A decorator for retrying an async function.
 
@@ -48,9 +48,9 @@ def retry_async_fn(
 
     def decorator(
         func: Callable[P, Coroutine[Any, Any, R]],
-    ) -> Callable[P, Coroutine[Any, Any, Optional[R]]]:
+    ) -> Callable[P, Coroutine[Any, Any, R]]:
         @wraps(func)
-        async def wrapper(*args: P.args, **kwargs: P.kwargs) -> Optional[R]:
+        async def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
             name = operation_name or func.__name__
             for attempt in range(max_attempts):
                 try:
@@ -67,6 +67,9 @@ async def wrapper(*args: P.args, **kwargs: P.kwargs) -> Optional[R]:
                         f"Retrying in {delay:.2f} seconds..."
                     )
                     await asyncio.sleep(delay)
+            # Technically unreachable, but this raise helps pyright know that this function
+            # won't return None.
+            raise Exception(f"Function {name!r} failed after {max_attempts} attempts")
 
         return wrapper
 

src/prefect/server/events/schemas/automations.py

@@ -317,7 +317,7 @@ class EventTrigger(ResourceTrigger):
     @model_validator(mode="before")
     @classmethod
     def enforce_minimum_within_for_proactive_triggers(
-        cls, data: Dict[str, Any]
+        cls, data: Dict[str, Any] | Any
     ) -> Dict[str, Any]:
         if not isinstance(data, dict):
             return data
@@ -342,7 +342,7 @@ def enforce_minimum_within_for_proactive_triggers(
 
         return data
 
-    def covers(self, event: ReceivedEvent):
+    def covers(self, event: ReceivedEvent) -> bool:
         if not self.covers_resources(event.resource, event.related):
             return False
 
@@ -356,10 +356,10 @@ def immediate(self) -> bool:
         """Does this reactive trigger fire immediately for all events?"""
         return self.posture == Posture.Reactive and self.within == timedelta(0)
 
-    _event_pattern: Optional[re.Pattern] = PrivateAttr(None)
+    _event_pattern: Optional[re.Pattern[str]] = PrivateAttr(None)
 
     @property
-    def event_pattern(self) -> re.Pattern:
+    def event_pattern(self) -> re.Pattern[str]:
         """A regular expression which may be evaluated against any event string to
         determine if this trigger would be interested in the event"""
         if self._event_pattern:
@@ -625,13 +625,15 @@ class Firing(PrefectBaseModel):
 
     id: UUID = Field(default_factory=uuid4)
 
-    trigger: ServerTriggerTypes = Field(..., description="The trigger that is firing")
+    trigger: Union[ServerTriggerTypes, CompositeTrigger] = Field(
+        default=..., description="The trigger that is firing"
+    )
     trigger_states: Set[TriggerState] = Field(
-        ...,
+        default=...,
         description="The state changes represented by this Firing",
     )
     triggered: DateTime = Field(
-        ...,
+        default=...,
         description=(
             "The time at which this trigger fired, which may differ from the "
             "occurred time of the associated event (as events processing may always "
@@ -654,16 +656,16 @@ class Firing(PrefectBaseModel):
         ),
     )
     triggering_event: Optional[ReceivedEvent] = Field(
-        None,
+        default=None,
         description=(
             "The most recent event associated with this Firing.  This may be the "
             "event that caused the trigger to fire (for Reactive triggers), or the "
             "last event to match the trigger (for Proactive triggers), or the state "
             "change event (for a Metric trigger)."
         ),
     )
-    triggering_value: Any = Field(
-        None,
+    triggering_value: Optional[Any] = Field(
+        default=None,
         description=(
             "A value associated with this firing of a trigger.  Maybe used to "
             "convey additional information at the point of firing, like the value of "

src/prefect/server/events/services/actions.py

@@ -1,23 +1,28 @@
+from __future__ import annotations
+
 import asyncio
-from typing import Optional
+from typing import TYPE_CHECKING, NoReturn
 
 from prefect.logging import get_logger
 from prefect.server.events import actions
-from prefect.server.utilities.messaging import create_consumer
+from prefect.server.utilities.messaging import Consumer, create_consumer
+
+if TYPE_CHECKING:
+    import logging
 
-logger = get_logger(__name__)
+logger: "logging.Logger" = get_logger(__name__)
 
 
 class Actions:
     """Runs actions triggered by Automatinos"""
 
     name: str = "Actions"
 
-    consumer_task: Optional[asyncio.Task] = None
+    consumer_task: asyncio.Task[None] | None = None
 
-    async def start(self):
+    async def start(self) -> NoReturn:
         assert self.consumer_task is None, "Actions already started"
-        self.consumer = create_consumer("actions")
+        self.consumer: Consumer = create_consumer("actions")
 
         async with actions.consumer() as handler:
             self.consumer_task = asyncio.create_task(self.consumer.run(handler))
@@ -28,7 +33,7 @@ async def start(self):
             except asyncio.CancelledError:
                 pass
 
-    async def stop(self):
+    async def stop(self) -> None:
         assert self.consumer_task is not None, "Actions not started"
         self.consumer_task.cancel()
         try:

src/prefect/server/events/services/event_logger.py

@@ -1,26 +1,31 @@
+from __future__ import annotations
+
 import asyncio
-from typing import Optional
+from typing import TYPE_CHECKING, NoReturn
 
 import pendulum
 import rich
 
 from prefect.logging import get_logger
 from prefect.server.events.schemas.events import ReceivedEvent
-from prefect.server.utilities.messaging import Message, create_consumer
+from prefect.server.utilities.messaging import Consumer, Message, create_consumer
+
+if TYPE_CHECKING:
+    import logging
 
-logger = get_logger(__name__)
+logger: "logging.Logger" = get_logger(__name__)
 
 
 class EventLogger:
     """A debugging service that logs events to the console as they arrive."""
 
     name: str = "EventLogger"
 
-    consumer_task: Optional[asyncio.Task] = None
+    consumer_task: asyncio.Task[None] | None = None
 
-    async def start(self):
+    async def start(self) -> NoReturn:
         assert self.consumer_task is None, "Logger already started"
-        self.consumer = create_consumer("events")
+        self.consumer: Consumer = create_consumer("events")
 
         console = rich.console.Console()
 
@@ -46,7 +51,7 @@ async def handler(message: Message):
         except asyncio.CancelledError:
             pass
 
-    async def stop(self):
+    async def stop(self) -> None:
         assert self.consumer_task is not None, "Logger not started"
         self.consumer_task.cancel()
         try:

src/prefect/server/events/services/event_persister.py

@@ -3,10 +3,12 @@
 storage as fast as it can.  Never gets tired.
 """
 
+from __future__ import annotations
+
 import asyncio
 from contextlib import asynccontextmanager
 from datetime import timedelta
-from typing import AsyncGenerator, List, Optional
+from typing import TYPE_CHECKING, AsyncGenerator, List, NoReturn
 
 import pendulum
 import sqlalchemy as sa
@@ -15,25 +17,33 @@
 from prefect.server.database import provide_database_interface
 from prefect.server.events.schemas.events import ReceivedEvent
 from prefect.server.events.storage.database import write_events
-from prefect.server.utilities.messaging import Message, MessageHandler, create_consumer
+from prefect.server.utilities.messaging import (
+    Consumer,
+    Message,
+    MessageHandler,
+    create_consumer,
+)
 from prefect.settings import (
     PREFECT_API_SERVICES_EVENT_PERSISTER_BATCH_SIZE,
     PREFECT_API_SERVICES_EVENT_PERSISTER_FLUSH_INTERVAL,
     PREFECT_EVENTS_RETENTION_PERIOD,
 )
 
-logger = get_logger(__name__)
+if TYPE_CHECKING:
+    import logging
+
+logger: "logging.Logger" = get_logger(__name__)
 
 
 class EventPersister:
     """A service that persists events to the database as they arrive."""
 
     name: str = "EventLogger"
 
-    consumer_task: Optional[asyncio.Task] = None
+    consumer_task: asyncio.Task[None] | None = None
 
     def __init__(self):
-        self._started_event: Optional[asyncio.Event] = None
+        self._started_event: asyncio.Event | None = None
 
     @property
     def started_event(self) -> asyncio.Event:
@@ -45,9 +55,9 @@ def started_event(self) -> asyncio.Event:
     def started_event(self, value: asyncio.Event) -> None:
         self._started_event = value
 
-    async def start(self):
+    async def start(self) -> NoReturn:
         assert self.consumer_task is None, "Event persister already started"
-        self.consumer = create_consumer("events")
+        self.consumer: Consumer = create_consumer("events")
 
         async with create_handler(
             batch_size=PREFECT_API_SERVICES_EVENT_PERSISTER_BATCH_SIZE.value(),
@@ -64,7 +74,7 @@ async def start(self):
             except asyncio.CancelledError:
                 pass
 
-    async def stop(self):
+    async def stop(self) -> None:
         assert self.consumer_task is not None, "Event persister not started"
         self.consumer_task.cancel()
         try:

src/prefect/server/events/services/triggers.py

@@ -1,25 +1,30 @@
+from __future__ import annotations
+
 import asyncio
-from typing import Optional
+from typing import TYPE_CHECKING, Any, NoReturn, Optional
 
 from prefect.logging import get_logger
 from prefect.server.events import triggers
 from prefect.server.services.loop_service import LoopService
-from prefect.server.utilities.messaging import create_consumer
+from prefect.server.utilities.messaging import Consumer, create_consumer
 from prefect.settings import PREFECT_EVENTS_PROACTIVE_GRANULARITY
 
-logger = get_logger(__name__)
+if TYPE_CHECKING:
+    import logging
+
+logger: "logging.Logger" = get_logger(__name__)
 
 
 class ReactiveTriggers:
     """Runs the reactive triggers consumer"""
 
     name: str = "ReactiveTriggers"
 
-    consumer_task: Optional[asyncio.Task] = None
+    consumer_task: asyncio.Task[None] | None = None
 
-    async def start(self):
+    async def start(self) -> NoReturn:
         assert self.consumer_task is None, "Reactive triggers already started"
-        self.consumer = create_consumer("events")
+        self.consumer: Consumer = create_consumer("events")
 
         async with triggers.consumer() as handler:
             self.consumer_task = asyncio.create_task(self.consumer.run(handler))
@@ -30,7 +35,7 @@ async def start(self):
             except asyncio.CancelledError:
                 pass
 
-    async def stop(self):
+    async def stop(self) -> None:
         assert self.consumer_task is not None, "Reactive triggers not started"
         self.consumer_task.cancel()
         try:
@@ -43,7 +48,7 @@ async def stop(self):
 
 
 class ProactiveTriggers(LoopService):
-    def __init__(self, loop_seconds: Optional[float] = None, **kwargs):
+    def __init__(self, loop_seconds: Optional[float] = None, **kwargs: Any):
         super().__init__(
             loop_seconds=(
                 loop_seconds
@@ -52,5 +57,5 @@ def __init__(self, loop_seconds: Optional[float] = None, **kwargs):
             **kwargs,
         )
 
-    async def run_once(self):
+    async def run_once(self) -> None:
         await triggers.evaluate_proactive_triggers()