Adds MAX_RRULE_LENGTH

docs/concepts/schedules.md

@@ -178,6 +178,9 @@ schedule:
   rrule: 'FREQ=WEEKLY;BYDAY=MO,WE,FR;UNTIL=20240730T040000Z'
 ```
 
+!!! info "Max RRule length"
+    Note the max supported character length of an `rrulestr` is 6500 characters
+
 !!! info "Daylight saving time considerations"
     Note that as a calendar-oriented standard, `RRules` are sensitive to the initial timezone provided. A 9am daily schedule with a DST-aware start date will maintain a local 9am time through DST boundaries. A 9am daily schedule with a UTC start date will maintain a 9am UTC time.
 

src/prefect/orion/schemas/schedules.py

@@ -15,6 +15,8 @@
 from prefect.orion.utilities.schemas import DateTimeTZ, PrefectBaseModel
 
 MAX_ITERATIONS = 1000
+# approx. 1 years worth of RDATEs + buffer
+MAX_RRULE_LENGTH = 6500
 
 
 def _prepare_scheduling_start_and_end(
@@ -394,6 +396,11 @@ def validate_rrule_str(cls, v):
             # rrules errors are a mix of cryptic and informative
             # so reraise to be clear that the string was invalid
             raise ValueError(f'Invalid RRule string "{v}": {exc}')
+        if len(v) > MAX_RRULE_LENGTH:
+            raise ValueError(
+                f'Invalid RRule string "{v}"\n'
+                f"Max length is {MAX_RRULE_LENGTH}, got {len(v)}"
+            )
         return v
 
     @classmethod

tests/orion/schemas/test_schedules.py

@@ -11,6 +11,7 @@
 
 from prefect.orion.schemas.schedules import (
     MAX_ITERATIONS,
+    MAX_RRULE_LENGTH,
     CronSchedule,
     IntervalSchedule,
     RRuleSchedule,
@@ -634,13 +635,6 @@ async def test_rrule_returns_nothing_before_dtstart(self):
         dates = await s.get_dates(5, start=pendulum.now("UTC"))
         assert dates == [pendulum.datetime(2030, 1, 1).add(days=i) for i in range(5)]
 
-    async def test_rrule_returns_nothing_before_dtstart(self):
-        s = RRuleSchedule.from_rrule(
-            rrule.rrule(freq=rrule.DAILY, dtstart=pendulum.datetime(2030, 1, 1))
-        )
-        dates = await s.get_dates(5, start=pendulum.now("UTC"))
-        assert dates == [pendulum.datetime(2030, 1, 1).add(days=i) for i in range(5)]
-
     async def test_rrule_validates_rrule_str(self):
         # generic validation error
         with pytest.raises(ValidationError, match="(Invalid RRule string)"):
@@ -654,6 +648,15 @@ async def test_rrule_validates_rrule_str(self):
         with pytest.raises(ValidationError, match="(invalid 'FREQ': DAILYBAD)"):
             RRuleSchedule(rrule="FREQ=DAILYBAD")
 
+    async def test_rrule_max_rrule_len(self):
+        start = datetime(2000, 1, 1)
+        s = "RDATE:" + ",".join(
+            [start.add(days=i).format("YMMDD") + "T000000Z" for i in range(365 * 3)]
+        )
+        assert len(s) > MAX_RRULE_LENGTH
+        with pytest.raises(ValidationError, match="Max length"):
+            RRuleSchedule(rrule=s)
+
     async def test_rrule_schedule_handles_complex_rrulesets(self):
         s = RRuleSchedule(
             rrule="DTSTART:19970902T090000\n"