Architecture

The structure of gringotts

gringotts is an OTP application and launches a worker when it is started. All calls made to the API (ie, Gringotts.*() calls) are serviced by this worker.

The merchants provide their authentication secrets for each of the Gateway they use in the Application config. You can see an example of the config/config.exs in the example repo.

Currently, gringotts does not fetch the secrets from the system environment.

This information is picked by the worker and is added to the opts argument under the :config key. Let's say GatewayXYZ gives the merchant an :api_key, then the merchant would put this in his config.exs:

config :gringotts, Gringotts.Gateways.GatewayXYZ,
    adapter: Gringotts.Gateways.GatewayXYZ,
    api_key: "merchant's_valuable_secret",

A call to

Gringotts.purchase(GatewayXYZ, amount, card, foo: "bar")

will eventually hit the GatewayXYZ module

GatewayXYZ.purchase(
    amount,
    card,
    [config: %{api_key: "merchant's_valuable_secret"},
     foo: "bar"]
)

So during development, we recommend adding a variable binding for the opts argument:

opts = [config: {auth_key: "your_secret_value"}] ++ other_opts

instead of providing this information in gringotts/config/config.exs. See Adding a new Gateway for a concrete example.

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Where to next? Wanna add a new gateway? Head to our guide for that.