Dynamic Load Balancer with Auto-Scaling — Bun + Express

TL;DR: I prototyped a dynamic, CPU-aware load balancer that spins backend instances locally using bun run, performs health checks, and auto-scales based on real-time traffic. Built in a focused 4-hour sprint.

Why build a local ASG replacement?

I wanted to understand ASG mechanics without vendor lock-in. The goal was to replicate the core behaviors (spawn, route, health-check, scale) in a minimal, transparent system.

Features

• Spins backend instances (each on configurable ports)
• Health checks + route only to healthy targets
• Auto-scale up/down based on configured thresholds
• CPU-aware sharding for the balancer itself to avoid single-threaded bottlenecks
• Simple config.yaml for instance definitions and scaling policies
• Live /lb-status dashboard for quick monitoring

Implementation notes

• Core runner: Bun (fast startup) launching child processes
• Router: Express for HTTP routing and dashboard
• Health checks: periodic, pluggable handlers for HTTP/TCP
• Configuration: YAML (easy to edit and read)

Repo & demo

• Quick start: clone repo and run bun run start --config config.yaml
• Repository: https://github.com/Adityaadpandey/Load_Balancer (check README for examples) — or see my GitHub profile for the project. :contentReference[oaicite:3]{index=3}