cloud-architecture-gcplisted

# GCP Architecture Knowledge Service-level detail for a GCP-backed project. Pairs with Melvin's cloud-agnostic diagnostic checklist (traffic pattern, state location, SLAs, blast radius, cost explosion, coordination, limits, observability) — this pack supplies the GCP-specific answers. For concrete topology, cost tiers, and stack context, read the architecture docs named in `CLAUDE.md`. ## Compute ### Cloud Run - Serverless containers, request- or instance-billed, **scales to zero**. The cost win and the latency trap: a scaled-to-zero service pays a **cold start** (image pull + container start) on the next request. Set **`min-instances >= 1`** to keep a warm instance for latency-sensitive paths — the Cloud Run analogue of provisioned concurrency. - **Concurrency:** one Cloud Run instance serves *multiple* concurrent requests (default up to 80, tunable) — unlike Lambda's one-request-per-instance. Right concurrency setting massively affects cost and tail latency; CPU-bound work wants lower concurrency, IO-bound can go higher. `--cpu-throttling` (CPU only during requests) vs always-on CPU (for background work) is a real cost lever. - **Limits:** per-service max instances (set it to cap blast radius and spend), request timeout up to 60 min, memory/CPU per instance. Cloud Run **jobs** for run-to-completion batch (vs services for request serving). - **Good for:** HTTP APIs, event consumers (Eventarc/Pub/Sub push), web apps. Prefer it over GKE unless you nee