title: How to do proxy over proxy (2 layers) by using scrapy?
body: <p>How to do proxy over proxy (2 layers) by using <a href="http://scrapy.org/" rel="nofollow">scrapy</a>? I assume here are the http/https proxies.</p>
  
  <p>For example, my local machine -->proxy1 -->proxy2 --> the site I want to crawl.
  How to do that in scrapy?</p>
  
  <p>Why I want to do this?</p>
  
  <p>The goal is to hide my ip address. You can think that proxy1 is very reliable, but it was blocked by the site I want to crawl. And the proxy2 is not reliable but have access to the site I want to crawl. </p>
  
  <p>I could do my local machine -->proxy2 --> the site I want to crawl. But because proxy2 is not reliable, so I could expose my ip address to the site I want to crawl. So I want to add another layer before proxy2 to protect it.</p>