Sidekiq + Grocer

message.rb

class Message
  include Mongoid::Document
  include Mongoid::Timestamps

  field :alert, type: String
  field :badge, type: Integer, default: 0
  field :sound, type: String
  field :schedule, type: DateTime
  field :custom, type: Hash

  after_create :deliver
  
  private
  
  def deliver
    MessageWorker.perform_async(self.id.to_s)
  end
end

message_worker.rb

class MessageWorker
  include Sidekiq::Worker
  sidekiq_options :retry => false

  def perform(message_id)
    message = Message.find(message_id)

    pusher = Grocer.pusher(
      certificate: @message.project_pem_file,
      gateway: ENV["APN_GATEWAY"],
      port: 2195
    )

    message.devices.each do |device|
      notification = Grocer::Notification.new(
        device_token: device.token,
        alert: message.alert,
        badge: message.badge,
        sound: message.sound,
        custom: message.custom
      )
      
      pusher.push(notification)
    end
  end
end