Url shortener with google api client

Not working as the referer url is not matching!
---
gem 'google-api-client'
---
require 'google/apis/urlshortener_v1'

Urlshortener = Google::Apis::UrlshortenerV1

class ThirdPartyApi::Google::UrlShortener
  def initialize
    @shortener = Urlshortener::UrlshortenerService.new
    @shortener.authorization = nil
    @shortener.key = Rails.application.secrets.google['api_key']
    @shortener.request_options = @shortener.request_options.merge(header: ["Referer: #{Settings.koolicar.host}"])
  end

  def shorten(url)
    response = Urlshortener::Url.new(long_url: url)
    shortened_url = @shortener.insert_url(response).try(:id)
    Rollbar.error("Failed to generate a shorten url for #{url}") unless shortened_url.present?
    shortened_url
  end
end