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Rex Server – Reverse Proxy & Load Balancer
Technical deep‑dive for Rex Server, a Node.js-based reverse proxy and load balancer using master-worker clustering and YAML configuration.
Technology Stack
node.js
express
typescript
yaml
reverse-proxy
load-balancing
Key Challenges
- Minimizing latency while proxying API and static requests across worker processes.
- Designing a scalable master–worker cluster capable of automatically redistributing traffic when workers crash or restart.
- Ensuring zero downtime during worker restarts and avoiding thundering-herd problems.
- Building a custom routing engine that supports wildcard patterns, nested paths, and priority-based matching.
- Handling tens of thousands of open HTTP connections efficiently without memory leaks.
- Implementing robust YAML configuration validation and auto-reloading without breaking active requests.
Key Learnings
- Deep understanding of Node.js event loop internals, worker_threads vs cluster module, IPC channels, and message passing.
- Building high-performance HTTP reverse proxies using Node’s low-level http module instead of frameworks.
- Optimizing network I/O, streaming responses, handling backpressure, and preventing stalled pipelines.
- Implementing a master server architecture: worker lifecycle management, watchdog timers, and crash recovery.
- Understanding Linux-level networking concepts like file descriptors, socket reuse, and connection draining.
- Designing CLI tools using Node’s fs + YAML parsing + shell command orchestration.
Rex Server – Reverse Proxy & Load Balancer
Rex Server is a Node.js-based reverse proxy and load balancer distributed as an npm package. It uses a master–worker architecture for concurrency and reliability.
Features
- Reverse proxying
- Load balancing
- Static file serving
- YAML-based configuration
- CLI workflow
- Auto worker restart
Installation
npm install -g rex-serverInitialize:
rex --initConfig Example
server:
instances:
- port: 80
public: "/absolute/path/to/public"
routes:
- path: "/api"
destination: http://localhost:3000
- path: "/*"
destination: http://localhost:5173
workers: autoMaster–Worker Design
- Master supervises workers
- Workers handle requests
- Auto‑restart on crash
- Multi‑core utilization
CLI
rex --init
rex load rex.config.yaml
rex start
rex stop
rex stop -p <PID>Routing Behavior
Example:
/api→ backend API/*→ frontend fallback
Use Cases
- Lightweight reverse proxy
- Dev environment routing
- Static hosting + backend APIs
- NGiNX alternative for JS environments
Conclusion
Rex Server offers an easy, developer‑friendly way to run proxies and load balancers entirely in Node.js.