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Cover image for S3cret Agent: Build an AI That Generates AWS Presigned URLs on Command
Chandrani Mukherjee
Chandrani Mukherjee

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S3cret Agent: Build an AI That Generates AWS Presigned URLs on Command

#langchain #docker #aws #python

This project implements an AI-powered LangChain agent that dynamically generates AWS S3 Presigned URLs (GET or PUT) based on natural language input. The agent is wrapped in a FastAPI server and supports integration into secure backend workflows.

🧠 What It Does

  • Accepts input like: Generate download link bucket=my-bucket key=path/to/file.txt
  • Uses LangChain tools to interpret commands
  • Generates a presigned URL via boto3
  • Responds with a secure, time-limited URL (GET/PUT)

🧱 Tech Stack

📁 Folder Structure

langchain_s3_agent/
├── main.py # FastAPI app
├── agent.py # LangChain agent logic
├── aws_utils.py # Presigned URL generator
├── .env # AWS credentials (not committed)
├── requirements.txt
└── Dockerfile (optional)

🚀 Quick Start

1️⃣ Clone and Install 

git clone https://github.com/your-repo/langchain-s3-agent.git
cd langchain-s3-agent
pip install -r requirements.txt
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2️⃣ Add AWS Credentials to .env
env
AWS_ACCESS_KEY_ID=your_key
AWS_SECRET_ACCESS_KEY=your_secret
AWS_REGION=us-east-1
3️⃣ Run the API

uvicorn main:app --reload
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📡 How to Use
POST /query
Request Body:


{
  "query": "Generate download link bucket=my-bucket key=path/to/file.txt"
}
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Response:


{
  "response": "GET URL for `path/to/file.txt`: https://s3.amazonaws.com/..."
}
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🧠 Supported Prompts
Action Prompt Format Example
Download Generate download link bucket=my-bucket key=folder/file.txt
Upload Generate upload link bucket=my-bucket key=uploads/newfile.txt

🧪 Example CURL Test


curl -X POST http://localhost:8000/query \
  -H "Content-Type: application/json" \
  -d '{"query": "Generate upload link bucket=my-bucket key=upload/test.txt"}'
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🐳 Optional: Docker Support
Dockerfile
dockerfile

FROM python:3.11

WORKDIR /app

COPY . .

RUN pip install -r requirements.txt

CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]
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Build & Run

docker build -t s3-agent .
docker run -p 8000:8000 --env-file .env s3-agent
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🔐 IAM Policy Required
Your AWS IAM user or role must have:


{
  "Effect": "Allow",
  "Action": ["s3:GetObject", "s3:PutObject"],
  "Resource": "arn:aws:s3:::your-bucket-name/*"
}
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📌 Roadmap Ideas
Add expiration input (expires_in=600)

Enable presigned POST for HTML form uploads

Add token auth to protect the API

Web UI with React or Streamlit

📘 Resources
AWS S3 Presigned URLs

Boto3 Docs

LangChain Docs

FastAPI Docs

Top comments (2)

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aiden_benjamin_52c3f6771f profile image
Aiden Benjamin •

Absolutely brilliant idea—turning presigned URL generation into a natural language task is next-level productivity!

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geogina_smith_0ed8471bb3c profile image
Geogina Smith •

Very intelligent