Built a lightweight Prometheus tool to rightsize CPU/RAM

I recently had to urgently optimize resources across 200 servers in our environment. Our cloud provider doesn’t offer any built-in rightsizing or capacity optimization tools, and I couldn’t find a simple open-source solution focused specifically on CPU/RAM rightsizing based on Prometheus metrics. The goal was simple: Analyze historical usage Calculate realistic resource requirements Identify reclaimable CPU cores and RAM The tool: Pulls metrics from Prometheus Calculates p95 CPU usage (non-idle cores, summed per instance) Calculates p95 RAM usage Applies a configurable safety margin (default 20%) Ensures CPU minimum = 1 core Rounds RAM to 0.5 GB Generates: Reclaim recommendations Grow recommendations (if under-provisioned) Provides a simple web UI to explore: Total reclaimable CPU/RAM Per-job breakdown Per-host details It supports: Linux (node_exporter) Windows (windows_exporter) Architecture is intentionally simple: Prometheus → Analyzer → JSON → FastAPI → Web UI It’s not meant to rep