BalancerX

🚀 A lightweight, dynamic, and customizable Load Balancer built in Go (Golang) with multiple routing strategies, active health checks, real-time dashboard, and live backend management.

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✨ Features

🔄 Multi-Strategy Routing

BalancerX supports four load-balancing algorithms (configurable via JSON):

• Round Robin — simple cyclical distribution
• Weighted Round Robin — distributes traffic relative to server weight
• Least Connections — sends requests to the server with the fewest active connections
• IP Hash — sticky sessions based on client IP

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⚙️ Dynamic Configuration

• Add/remove backend servers without restarting the load balancer
• Fully JSON-driven configuration

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❤️ Active Health Checks

• Periodically probes each backend’s /health (or custom) endpoint
• Automatically removes unhealthy backends from rotation
• Restores them once they recover

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🖥️ Real-Time Dashboard

UI available at:

http://localhost:8080/ui

View:

• Server health (green/red)
• Active connections
• Traffic routing
• Add/remove servers live

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🧵 Concurrency-Safe Architecture

• sync.RWMutex for read-optimized backend pool
• sync/atomic for counters (active requests, RR index)
• Goroutines for parallel health checks & proxying

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🔁 Smart Retry Mechanism

If a backend fails during a request:

1. Proxy detects failure
2. Tracks retry attempts
3. Automatically routes the request to next healthy server

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📁 Project Structure

/balancerx
  ├── config.json       # Dynamic configuration file
  ├── main.go           # Entry point, server, API, dashboard
  ├── models.go         # Backend, ServerPool structures
  ├── strategies.go     # Round Robin, WRR, LC, IP-Hash algorithms
  └── utils.go          # Health checks, config loader

/backend
  └── main.go           # Simple dummy backend for testing

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🛠️ Getting Started

Prerequisites

• Go 1.18+

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🔧 1. Installation

git clone https://github.com/shubhamc1947/balancerx.git
cd balancerx

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⚙️ 2. Configuration

Edit balancerx/config.json:

{
  "server_port": ":8080",
  "health_check_interval": "10s",
  "lb_strategy": "least-connection",
  "backends": [
    {
      "url": "http://localhost:8081",
      "weight": 1,
      "health_path": "/"
    }
  ]
}

Supported Strategies:

Strategy	Value
Round Robin	"round-robin"
Weighted Round Robin	"weighted-round-robin"
Least Connections	"least-connection"
IP Hash	"ip-hash"

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▶️ 3. Running the System

Step 1 — Start Dummy Backends

This starts 3 test backends on ports 8081, 8082, 8083:

go run backend/main.go

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Step 2 — Start BalancerX

go run ./balancerx

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🖥️ Dashboard

Open:

http://localhost:8080/ui

From the control panel you can:

• ✔ See backend status
• ✔ Monitor live connections
• ✔ Add a new server
• ✔ Remove a server

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🔌 API Reference

List Backends

GET /api/backends

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Add Backend

POST /api/backends

Example:

curl -X POST http://localhost:8080/api/backends \
  -d '{"url": "http://localhost:8084", "weight": 2, "health_path": "/"}'

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Remove Backend

DELETE /api/backends

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🧠 Architecture Highlights

Concurrency Model

• 🧵 Goroutines — non-blocking request forwarding & health checks
• 🔐 Atomic Counters — RR index, active connections
• 🔒 RWMutex — safe concurrent backend management

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Resilience

• Custom ReverseProxy error handler
• Automatic retries to next healthy backend
• Context-aware retry limit

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🔮 Future Improvements

• Weighted Least Connections
• Prometheus /metrics exporter
• HTTPS/TLS termination
• Rate limiting

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📝 License

This project is licensed under the MIT License.