Adds an asyncio background task that re-runs the heavy Ingest Dashboard
queries every ~4 min (just under the 5 min TTL) so the in-process cache
is always populated. First user hit on any dashboard widget then returns
from cache (single-digit ms) instead of waiting 30-60s for SDL.
Components:
- backend/services/prewarmer.py: standalone module, opt-in via
INGEST_PREWARM=1; configurable windows via INGEST_PREWARM_HOURS /
INGEST_PREWARM_DAYS / INGEST_PREWARM_DAILY_VOLUME_DAYS and interval
via INGEST_PREWARM_INTERVAL_SECONDS. Logs through the uvicorn logger
so cycles are visible in 'docker logs'.
- backend/main.py: spawn the task on FastAPI startup.
- docker-compose.yml: forward INGEST_PREWARM* env vars to the
backend service (default off).
Observed on a busy tenant with INGEST_PREWARM=1, default windows:
top-sources?days=7 first hit after restart: ~39s -> ~8ms (cache warm).
Defaults to disabled (INGEST_PREWARM=0) so existing users see no
behaviour change.
marc