# Cache Proposal for Kubectl Web GUI

## Problem
With ~1600 pods, loading full lists from kubectl is slow. We need backend caching with background renewal so users are not blocked.

## Ideas

### 1. In-Memory TTL Cache with Background Refresh
- Store parsed item lists in a Python dict with 5-minute TTL.
- A background thread (threading.Timer or asyncio) refreshes each resource type every 4 minutes.
- Users always read from memory; refresh is invisible.

### 2. Stale-While-Revalidate Pattern
- Serve cached data immediately.
- If cache is older than 3 minutes, trigger a background kubectl call to update it.
- User gets fast response; data updates shortly after.

### 3. Per-Resource Background Workers
- One lightweight thread per resource (pods, nodes, pvcs, configmaps).
- Each thread runs kubectl on its own interval (e.g., 4 min).
- Cache is always warm; no user request triggers kubectl unless bypass is used.

### 4. Cache Invalidation on Actions
- After delete/cordon/uncordon, invalidate only that resource's cache.
- Next load will refresh just that resource, not all.

### 5. Partial / Chunked Cache
- Cache full list but paginate in backend.
- Background refresh updates the full list; pagination stays fast.

## Background Renewal Approach
- Use threading.Thread with a loop and time.sleep(240) per resource.
- Or use FastAPI startup event to spawn refresh tasks.
- Ensure thread-safe access to the shared cache dict (GIL helps, but use locks if needed).

## Trade-offs
- Memory usage: ~1600 pods is small; acceptable.
- Staleness: 4-5 minutes is okay for a local GUI.
- Refresh impact: background only, so app stays responsive.