Prom cost levers: scrape intervals, extra remote-write endpoints, relabel YAML, recording rules, HA Prom + Thanos/Mimir, shard-by-team. Elastic Serverless: one managed remote-write, keep resolution, Drop noise at ingest — no sidecar TSDB.
Use Metrics (not Discover). Time: Last 2 hours. Paste bare PromQL:
sum by (service.name) (http.server.requests)
sum by (service.name) (rate(http.server.requests[5m]))
sum by (service.name) (service.errors)