user_fetcher.rb

class UserFetcher
  def call
    connection.get("/users/#{user_id}")
  end
  
  private
  
  def connection
    Faraday.new(url: user_service_base_url) do |faraday|
      faraday.request :json
      faraday.response :json
      faraday.adapter Faraday.default_adapter
      faraday.headers.merge!(headers)
    end
  end
  
  ...
end