Webhook isn't fired or not registered

[Alegrria]

I have a Rails Shopify app, which belongs to different shops.

I tried to create a new webhook fulfillments/create with the shopify-app gem.

This is my config:

ShopifyApp.configure do |config|
  config.api_key = ENV["SHOPIFY_API_KEY"]
  config.secret = ENV["SHOPIFY_API_SECRET"]
  config.scope = ENV["SHOPIFY_SCOPE"]
  config.embedded_app = true
  config.webhook_jobs_namespace = "shopify_webhooks"
  config.webhooks =
    %w(
      app/uninstalled
      fulfillments/create
      orders/create
      shop/update
    ).map do |topic|
      {
        topic: topic,
        address: "https://#{ENV['APPLICATION_HOST']}/webhooks/#{topic.gsub(%r{/}, '_')}",
        format: "json",
      }
    end
end

and my job:

module ShopifyWebhooks
  class FulfillmentsCreateJob < WebhookJob
    def process_webhook(shop, webhook)
       # do something
    end
  end
end

However, i cannot see the webhook firing, when it should.
How can I check if the webhook exists? And if it does, why it is not firing? 

[Alegrria · Accepted solution]

I found out that I should have run a rake task on the app to register Webhooks.

Now everything works perfectly.