DNS Parser API

A Flask-based HTTP API that accepts base64-encoded DNS queries (RFC1035), decodes and parses them, logs request/response, and returns DNS questions and answers in JSON. It includes rate-limiting via Redis and DNS resolution fallback to local and public resolvers.

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🚀 Features

• Accepts base64-encoded DNS queries via POST /dns/queries
• Parses multiple DNS questions (RFC1035)
• Returns JSON with ID, questions, and DNS answers
• Performs DNS resolution with local and fallback resolvers
• Implements IP-based rate limiting using Redis
• Returns 429 Too Many Requests with Retry-After header
• Supports caching with ETag and If-None-Match
• Exposes health check at /healthz

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🗂 Project Structure

dns_parser/
├── dns_querier/      # Flask app logic
├── client/           # CLI tool to send DNS queries
├── e2e/              # End-to-end tests using testcontainers
├── tests/            # Unit tests
├── Dockerfile.server # Multi-stage minimal server image
├── docker-compose.yml
├── pyproject.toml
├── README.md

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🧪 Test Suite with TestContainers

This project uses testcontainers to run integration and e2e tests in isolated Docker-based environments.

✅ Install dependencies:

poetry install

▶️ Run all tests:

poetry run pytest

This will automatically spin up a Redis container for rate-limiting tests.

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🖥 Running the Server Locally

Using Poetry:

poetry run python run.py

Or using Docker:

docker build -f Dockerfile.server -t dns-parser-server .
docker run -p 5000:5000 dns-parser-server

Health check:

curl http://localhost:5000/healthz

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🧰 Using the CLI

The project includes a simple CLI tool to send DNS queries:

poetry run python client/cli.py www.google.com

You can change the endpoint URL using:

poetry run python client/cli.py www.google.com --url http://localhost:5000/dns/queries

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📂 GitHub Actions

• All tests are run via CI using pytest
• Docker image builds are only triggered if tests pass
• Separate workflows are used for test and image build stages

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📝 License

MIT