Harden Celery schedule parsing and startup safety

.env.example

@@ -66,6 +66,8 @@ PROVIDER_BALLDONTLIE_STATS_PER_PAGE=100
 CELERY_TASK_TIME_LIMIT=1800
 CELERY_TASK_SOFT_TIME_LIMIT=1500
 INGESTION_SCHEDULE_ENABLED=0
+# 5-field cron: minute hour day_of_month month day_of_week
+# Example hourly: 0 * * * *
 INGESTION_SCHEDULE_CRON=*/30 * * * *
 INGESTION_SCHEDULE_PROVIDER_NAMESPACE=
 INGESTION_SCHEDULE_JOB_TYPE=incremental

README.md

@@ -296,6 +296,18 @@ Configure scheduled sync through environment variables:
 When enabled, Celery Beat enqueues the scheduled sync task on the configured cron.
 The task uses the existing ingestion service path and writes run/error records in the same tables as manual sync.
 
+Valid cron examples:
+
+- `*/30 * * * *` every 30 minutes
+- `0 * * * *` hourly
+- `15 2 * * *` daily at 02:15
+
+Failure behavior for invalid cron values:
+
+- invalid `INGESTION_SCHEDULE_CRON` does not crash unrelated startup paths (for example, web)
+- periodic ingestion task is disabled until cron is fixed
+- an error is logged at startup indicating the invalid schedule value
+
 ## Provider Backend Selection
 
 Provider backend is selected via environment variables:

config/celery.py

@@ -1,9 +1,11 @@
+import logging
 import os
 from celery import Celery
 from celery.schedules import crontab
 from django.conf import settings
 
 os.environ.setdefault("DJANGO_SETTINGS_MODULE", "config.settings.development")
+logger = logging.getLogger(__name__)
 
 app = Celery("hoopscout")
 app.config_from_object("django.conf:settings", namespace="CELERY")
@@ -27,15 +29,25 @@ def _parse_cron_expression(expression: str) -> dict[str, str]:
 
 def build_periodic_schedule() -> dict:
     if not settings.INGESTION_SCHEDULE_ENABLED:
+        logger.info("Periodic ingestion schedule disabled by INGESTION_SCHEDULE_ENABLED=0.")
         return {}
 
-    schedule_kwargs = _parse_cron_expression(settings.INGESTION_SCHEDULE_CRON)
-    return {
-        "ingestion.scheduled_provider_sync": {
-            "task": "apps.ingestion.tasks.scheduled_provider_sync",
-            "schedule": crontab(**schedule_kwargs),
+    try:
+        schedule_kwargs = _parse_cron_expression(settings.INGESTION_SCHEDULE_CRON)
+        return {
+            "ingestion.scheduled_provider_sync": {
+                "task": "apps.ingestion.tasks.scheduled_provider_sync",
+                "schedule": crontab(**schedule_kwargs),
+            }
         }
-    }
+    except Exception as exc:  # noqa: BLE001
+        logger.error(
+            "Invalid periodic ingestion schedule config. Task disabled. "
+            "INGESTION_SCHEDULE_CRON=%r error=%s",
+            settings.INGESTION_SCHEDULE_CRON,
+            exc,
+        )
+        return {}
 
 
 app.conf.beat_schedule = build_periodic_schedule()

tests/test_celery_schedule_safety.py

@@ -0,0 +1,38 @@
+import os
+import subprocess
+import sys
+
+import pytest
+
+
+def _run_python_import(code: str, env_overrides: dict[str, str]) -> subprocess.CompletedProcess:
+    env = os.environ.copy()
+    env.update(env_overrides)
+    return subprocess.run(
+        [sys.executable, "-c", code],
+        capture_output=True,
+        text=True,
+        env=env,
+        check=False,
+    )
+
+
+@pytest.mark.django_db
+def test_invalid_cron_does_not_crash_config_import_path():
+    result = _run_python_import(
+        (
+            "import config; "
+            "from config.celery import app; "
+            "print(f'beat_schedule_size={len(app.conf.beat_schedule or {})}')"
+        ),
+        {
+            "DJANGO_SETTINGS_MODULE": "config.settings.development",
+            "DJANGO_ENV": "development",
+            "DJANGO_DEBUG": "1",
+            "INGESTION_SCHEDULE_ENABLED": "1",
+            "INGESTION_SCHEDULE_CRON": "bad cron value",
+        },
+    )
+
+    assert result.returncode == 0
+    assert "beat_schedule_size=0" in result.stdout

tests/test_ingestion_tasks.py

@@ -31,6 +31,18 @@ def test_build_periodic_schedule_disabled(settings):
     assert build_periodic_schedule() == {}
 
 
+@pytest.mark.django_db
+def test_build_periodic_schedule_invalid_cron_disables_task_and_logs(settings, caplog):
+    settings.INGESTION_SCHEDULE_ENABLED = True
+    settings.INGESTION_SCHEDULE_CRON = "invalid-cron"
+
+    with caplog.at_level("ERROR"):
+        schedule = build_periodic_schedule()
+
+    assert schedule == {}
+    assert any("Invalid periodic ingestion schedule config. Task disabled." in message for message in caplog.messages)
+
+
 @pytest.mark.django_db
 def test_trigger_incremental_sync_skips_overlapping_runs(settings):
     settings.INGESTION_PREVENT_OVERLAP = True