This is a basic proof of concept to test a read-through cache that proxies API requests to an external service.

The file configuration.rb contains the settings for both caching (through VCR) and the proxy configuration -- you can change the target endpoint here and configure any additional HTTP options recognized by the Net::HTTP standard library.

The entry point is implemented as a basic Sinatra app. To run:

$ bundle
$ ruby app.rb

The application intercepts all HTTP requests and calculates a signature based on the params and the request body and attempts to match that to an existing cached response (using VCR's built-in recording capabilities). On a cache hit, the stored response is returned, otherwise the request is forwarded to the live endpoint, cached, and the response is returned.

Requests that have the same signature but expect a different response on subsequent requests currently do not work. For example, a scenario where an item is added to a user's cart:

1. GET /carts/1 -- Initial request for a user's cart, the response will be cached based on the path.
2. POST /cart/items -- Request to add an item to the user's cart (with corresponding payload) that will result in a modification to the cart.
3. GET /carts/1 -- A second request to get the updated cart information. Rather than making a new request and fetching the updated data, this will return the cached response from request #1.

This proxy will not currently work in these situations.