Returner

Returner is a sample Elixir/Phoenix project that shows the past year returns for a bundle of stocks.

Installation

• Clone the repo
• Sign up for an Alpha Vantage API key
• Create config/test.secret.exs and config/dev.secret.exs using the API key and samples
• Install dependencies with mix deps.get
• Install Node.js dependencies with cd assets && npm install
• Start Phoenix endpoint with mix phx.server

Now you can visit localhost:4000 from your browser.

Architecture

• Returner exposes a simple API -- fetch_returns/0.
  • On app startup, Returner fetches the returns for the past year and caches them
• ReturnerWeb handles web requests

Testing

• By default the test suite doesn't run any tests that query the Alpha Vantage API
• To run external tests, do mix test --include external

Limitations

• The Alpha Vantage API's free plan is rate-limited to five requests per minute

TODO

• Update the returns cache with new returns every evening after market close.
• Cache the returns in an external database or memory store, so that they aren't lost when the app shuts down
• Create a deployment strategy