StripeEvent

StripeEvent is built on the ActiveSupport::Notifications API. Incoming webhook requests are authenticated with the webhook signature. Define subscribers to handle specific event types. Subscribers can be a block or an object that responds to #call.

Install

# Gemfile
gem 'stripe_event'

# config/routes.rb
mount StripeEvent::Engine, at: '/my-chosen-path' # provide a custom path

Usage

# config/initializers/stripe.rb
Stripe.api_key             = ENV['STRIPE_SECRET_KEY']     # e.g. sk_live_...
StripeEvent.signing_secret = ENV['STRIPE_SIGNING_SECRET'] # e.g. whsec_...

StripeEvent.configure do |events|
  events.subscribe 'charge.failed' do |event|
    # Define subscriber behavior based on the event object
    event.class       #=> Stripe::Event
    event.type        #=> "charge.failed"
    event.data.object #=> #<Stripe::Charge:0x3fcb34c115f8>
  end

  events.all do |event|
    # Handle all event types - logging, etc.
  end
end

Subscriber objects that respond to #call

class CustomerCreated
  def call(event)
    # Event handling
  end
end

class BillingEventLogger
  def initialize(logger)
    @logger = logger
  end

  def call(event)
    @logger.info "BILLING:#{event.type}:#{event.id}"
  end
end

StripeEvent.configure do |events|
  events.all BillingEventLogger.new(Rails.logger)
  events.subscribe 'customer.created', CustomerCreated.new
end

Subscribing to a namespace of event types

StripeEvent.subscribe 'customer.card.' do |event|
  # Will be triggered for any customer.card.* events
end

Securing your webhook endpoint

Authenticating webhooks with signatures

Stripe will cryptographically sign webhook payloads with a signature that is included in a special header sent with the request. Verifying this signature lets your application properly authenticate the request originated from Stripe. As of v2.0.0, StripeEvent now mandates that this feature be used. Please set the signing_secret configuration value:

StripeEvent.signing_secret = Rails.application.secrets.stripe_signing_secret

Please refer to Stripe's documentation for more details: https://stripe.com/docs/webhooks#signatures

Support for multiple signing secrets

Sometimes, you'll have multiple Stripe webhook subscriptions pointing at your application each with a different signing secret. For example, you might have both a main Account webhook and a webhook for a Connect application point at the same endpoint. It's possible to configure an array of signing secrets using the signing_secrets configuration option. The first one that successfully matches for each incoming webhook will be used to verify your incoming events.

StripeEvent.signing_secrets = [
  Rails.application.secrets.stripe_account_signing_secret,
  Rails.application.secrets.stripe_connect_signing_secret,
]

(NOTE: signing_secret= and signing_secrets= are just aliases for one another)

Configuration

If you have built an application that has multiple Stripe accounts--say, each of your customers has their own--you may want to define your own way of retrieving events from Stripe (e.g. perhaps you want to use the account parameter from the top level to detect the customer for the event, then grab their specific API key). You can do this:

class EventFilter
  def call(event)
    event.api_key = lookup_api_key(event.account)
    event
  end

  def lookup_api_key(account_id)
    Account.find_by!(stripe_account_id: account_id).api_key
  rescue ActiveRecord::RecordNotFound
    # whoops something went wrong - error handling
  end
end

StripeEvent.event_filter = EventFilter.new

If you'd like to ignore particular webhook events (perhaps to ignore test webhooks in production, or to ignore webhooks for a non-paying customer), you can do so by returning nil in your custom event_filter. For example:

StripeEvent.event_filter = lambda do |event|
  return nil if Rails.env.production? && !event.livemode
  event
end

StripeEvent.event_filter = lambda do |event|
  account = Account.find_by!(stripe_account_id: event.account)
  return nil if account.delinquent?
  event
end

Note: Older versions of Stripe used event.user_id to reference the Connect Account ID.

Without Rails

StripeEvent can be used outside of Rails applications as well. Here is a basic Sinatra implementation:

require 'json'
require 'sinatra'
require 'stripe_event'

Stripe.api_key = ENV['STRIPE_SECRET_KEY']

StripeEvent.subscribe 'charge.failed' do |event|
  # Look ma, no Rails!
end

post '/_billing_events' do
  data = JSON.parse(request.body.read, symbolize_names: true)
  StripeEvent.instrument(data)
  200
end

Testing

Handling webhooks is a critical piece of modern billing systems. Verifying the behavior of StripeEvent subscribers can be done fairly easily by stubbing out the HTTP signature header used to authenticate the webhook request. Tools like Webmock and VCR work well. RequestBin is great for collecting the payloads. For exploratory phases of development, UltraHook and other tools can forward webhook requests directly to localhost. You can check out test-hooks, an example Rails application to see how to test StripeEvent subscribers with RSpec request specs and Webmock. A quick look:

# spec/requests/billing_events_spec.rb
require 'rails_helper'

describe "Billing Events" do
  def bypass_event_signature(payload)
    event = Stripe::Event.construct_from(JSON.parse(payload, symbolize_names: true))
    expect(Stripe::Webhook).to receive(:construct_event).and_return(event)
  end

  describe "customer.created" do
    let(:payload) { file_fixture('evt_customer_created.json').read }
    before(:each) { bypass_event_signature(payload) }

    it "is successful" do
      post '/_billing_events', params: payload
      expect(response).to have_http_status(:success)
      # Additional expectations...
    end
  end
end

taise/stripe_event