faang-stonks

No affiliation with, but inspired by r/Superstonks.

Requirements

• Create a REST API where clients can retrieve stock data for FAANG companies
  • Optionally, clients can request historical data for one or more stocks
• Service should update stock prices every N minutes where N is configurable
• Service and supporting services (e.g., database, web layer, etc.) should be packages with Dockerfiles, and a docker-compose.yml file allowing full application instantiation.
• Use git for version control and frequently commit changes.

Motivation

This project is my attempt to find a happy medium between scalable, simple, flexible, simple, readable (i.e., not clever to the point of illegible code), secure, and simple. Simple's the hard part.

Discussion

The project's requirements don't specify the scale at which this service should operate. As such, I took my usual approach: keep things simple yet flexible to meet future requirements without the need for a complete code refactor.

For example, SQLite isn't the best choice for time-series data storage at scale, but it's good enough for this MVP in the absence of detailed scale requirements. I've included a stub for InfluxDB to illustrate how I could add support for it without affecting the rest of the code. I also included an in- memory implementation.

You'll find a similar pattern for financial data providers. I define an interface the rest of the code consumes, and then add an implementation of that interface for my financial data provider (IEX Cloud in this case).

API Resources

The API exposes two endpoints: one for retrieving all stocks and another for requesting quotes of a specific stock symbol. The API endpoints are versioned with v1.

• GET /v1/stocks
• GET /v1/stock/[symbol]

All timestamps returned by the API are in UTC.

Last N Quotes

Each API endpoint allows for an optional parameter last that will direct the API to return the last n quotes, or the maximum observed quotes, whichever is less.

GET /v1/stocks

Example: http://localhost:18081/v1/stocks

Response body:

{
  "aapl": [
    {
      "price": 130.4,
      "symbol": "aapl",
      "time": "2021-05-07T19:31:07.000000272Z"
    }
  ],
  "amzn": [
    {
      "price": 3296.16,
      "symbol": "amzn",
      "time": "2021-05-07T19:31:07.000000623Z"
    }
  ],
  "fb": [
    {
      "price": 320.125,
      "symbol": "fb",
      "time": "2021-05-07T19:31:05.000000929Z"
    }
  ],
  "goog": [
    {
      "price": 2402.14,
      "symbol": "goog",
      "time": "2021-05-07T19:30:21.000000201Z"
    }
  ],
  "nflx": [
    {
      "price": 504.08,
      "symbol": "nflx",
      "time": "2021-05-07T19:31:00.000000053Z"
    }
  ]
}

GET /v1/stock/goog

Example: http://localhost:18081/v1/stock/goog

Response body:

[
  {
    "price": 2403.06,
    "symbol": "goog",
    "time": "2021-05-07T19:32:08.000000511Z"
  }
]

GET /v1/stock/fb?last=3

Example: http://localhost:18081/v1/stock/goog?last=3

Response body:

[
  {
    "price": 320.12,
    "symbol": "fb",
    "time": "2021-05-07T19:36:02.000000631Z"
  },
  {
    "price": 319.92,
    "symbol": "fb",
    "time": "2021-05-07T19:35:09.000000338Z"
  },
  {
    "price": 319.99,
    "symbol": "fb",
    "time": "2021-05-07T19:34:08.00000012Z"
  }
]