fastapi-ticker-hub

A minimal, Kubernetes and Docker friendly mono-repo consisting of two services:

• poller: periodically fetches market data (via yfinance), computes diffs, publishes to Redis pub/sub, and maintains a full snapshot in Redis.
• api: exposes REST endpoints and WebSockets, serving the Redis snapshot and real-time diffs to clients (with optional per-connection watchlists).

Project structure using packages follows uv workspace guidance.

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Client example

const socket = new WebSocket("ws://localhost:8000/ws/prices");
socket.addEventListener("open", () => {
  setInterval(() => socket.send("ping"), 30000);
  socket.send(JSON.stringify({ watchlist: ["AAPL", "MSFT"] }));
});
socket.addEventListener("message", evt => {
  try { console.log("Update:", JSON.parse(evt.data)); }
  catch { console.warn("Non-JSON:", evt.data); }
});
socket.addEventListener("close", () => console.log("Closed"));
socket.addEventListener("error", e => console.error("WS error", e));

Prerequisites

• Python 3.13+ installed
• Docker & Docker Compose
• make (for convenience)

How It Works

1. poller service

   • settings.py reads TICKERS, POLL_FREQ, REDIS_URL from environment / .env .

   • main.py launches one asyncio task per symbol:

      while True:
        info = await to_thread(yf.Ticker(sym).info)
        await update_prices({ sym: data })
        await redis.publish("price-diffs", json.dumps(payload))
        await sleep(POLL_FREQ)

   • Maintains an in-memory snapshot map for fast merges, atomically SET prices in Redis.

   • Stores the latest full snapshot in a Redis hash (key prices).

   • Publishes incremental diffs on a Redis pub/sub channel (prices).

2. api service (REST)

   • GET /tickers - full snapshot from Redis (GET prices)
   • GET /tickers/{symbol} - one symbol or 404
   • GET /tickers/{symbol} - one symbol or 404
   • GET /tickers/{symbol}/history?start={start_date}&end={end_date} - one symbol or 404 - start and end date in format YYYY-MM-DD (2025-06-01)

3. api service (WebSockets)

   • /ws/prices — on connect, send full snapshot then stream diff messages
   • /ws/news — same pattern for news items
   • Clients may send { "watchlist": ["SYM",…] } to receive only those symbols.

   { "watchlist": ["AAPL", "MSFT", ...] }

Quick start (Docker Compose)

Simply clone the repo and run make start:

make start

• API available at http://localhost:8000
• WebSocket endpoints at ws://localhost:8000/ws/prices and /ws/news

Testing

Run unit tests:

make test

There is also an Azure CI pipeline that will run lint checks and execute tests.

Linting & Formatting

The project uses Ruff for linting, formatting and sorting imports for code consistency. Simply run:

make format