Add support for configuring rate limits via config.yaml to allow
administrators to tune the proxy for different deployment sizes.
Changes:
- Add RateLimitConfig struct to config.go with per_peer_interval_ms and per_peer_burst
- Update newRateLimiter() to accept optional RateLimitConfig parameter
- Load rate limit config from YAML and apply overrides to defaults
- Update tests to pass nil for default behavior
- Add comprehensive config.example.yaml with documentation
Configuration examples:
- Small (1-3 nodes): 1000ms interval, burst 5 (default)
- Medium (4-10 nodes): 500ms interval, burst 10
- Large (10+ nodes): 250ms interval, burst 20
Defaults remain conservative (1 req/sec, burst 5) to support most
deployments while allowing customization for larger environments.
Related: #46b8b8d08 (rate limit fix for multi-node support)
