📝 AI Summary Service

A lightweight, production-ready Go microservice that generates LLM-powered summaries, explanations, and text transformations using either OpenAI or a deterministic mock LLM for local/offline development.

This service is part of a 4-service AI Backend ecosystem that powers a full RAG (Retrieval-Augmented Generation) system.

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✨ Features

• POST /summary → Generate a summary or explanation from input text
• Real OpenAI support (gpt-4o-mini recommended)
• Deterministic mock mode for local development
• Clean Fiber HTTP API
• Structured logging (Zerolog)
• Metrics endpoint for observability
• Lightweight, fast, and deployable on Fly.io
• Fully containerized (Docker)

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🧠 Architecture Overview

flowchart TD

    A[Client / RAG Core] --> B[POST /summary]

    B --> C[Handler]
    C --> D[AI Layer]
    D --> E[OpenAI API or Mock LLM]

    E --> C
    C --> A

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📦 Project Structure

ai-summary-service/
├── main.go
├── go.mod
├── Dockerfile
├── .env.example
└── internal/
    ├── ai/
    │   └── llm.go
    ├── handlers/
    │   └── summary_handler.go
    └── middleware/
        ├── logger.go
        └── metrics.go

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🚀 Getting Started

1. Clone the repository

git clone https://github.com/ai-backend-course/ai-summary-service
cd ai-summary-service

2. Create your .env file

cp .env.example .env

3. Run locally

go run .

The service will start at:

http://localhost:8080

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🔧 Example Request

Endpoint

POST /summary

Request Body

{
  "text": "Golang is a fast, typed, compiled language designed for scalable backend systems."
}

Example Response (Real LLM)

{
  "summary": "Go is a fast, compiled language built for scalable backend systems."
}

Example Response (Mock LLM)

{
  "summary": "MOCK SUMMARY: Golang is a fast, typed..."
}

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⚙ Environment Variables

.env.example:

OPENAI_API_KEY=your_api_key_here
USE_LLM_MOCK=true
OPENAI_MODEL=gpt-4o-mini
PORT=8080
ENV=development

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📊 Metrics

GET /metrics

Example:

{
  "total_requests": 14,
  "total_errors": 0,
  "avg_latency_ms": 1.4
}

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🐳 Docker

Build & run

docker build -t ai-summary-service .
docker run -p 8080:8080 ai-summary-service

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☁️ Deploy to Fly.io

flyctl launch
flyctl secrets set OPENAI_API_KEY="your_key"
flyctl secrets set USE_LLM_MOCK=false
flyctl deploy

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📜 License

MIT License.