Siftsciex Plug

The Siftsciex Plug provides a very small API and logic for helping process Sift Science Decisions. If you need to handle a Decision Web Hook from Sift Science then you may find this useful.

The Decision Plug really does three things:

1. Checks for the Sift Science Signature in the request
2. Processes the body and transforms it into a Siftsciex.Decision.t struct
3. Maps specific endpoints to specific handlers

Installation

Available in Hex, the package can be installed by adding siftsciex_plug to your list of dependencies in mix.exs:

def deps do
  [
    {:siftsciex_plug, "~> 0.1.0"}
  ]
end

Example

The first thing you need to do is configure the expected Signature key from Sift Science, as well as the header where the signature should be found:

  config :siftsciex_plug,
    hook_key: <sift_science_signature>,
    sig_header: "x-sift-science-signature"

Then you can configure the Plug to process and route specific paths for you.

  alias Siftsciex.DecisionPlug

  forward "/sift_science", DecisionPlug, %{
    "bad_user" => {User, :sift_ban},
    "bad_listing" => {Listing, :sift_delete}
  }

Note

If you are using any Plug.Parsers then you will need to make sure that siftsciex_plug checks the body before the parser consumes it. To do this simply add the following to your Parser opts:

  body_reader: {Siftsciex.HookValidator, :validate, []}

In the case of a JSON parser the full config would look something like this:

plug Plug.Parsers,
    parsers: [:urlencoded, :multipart, :json],
    pass: ["*/*"],
    body_reader: {Siftsciex.HookValidator, :validate, []},
    json_decoder: Poison

Doing this allows siftsciex_plug to calculate the signature against the raw body.

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/siftsciex_plug.