title: scrapy crawler caught exception reading instance data
body: <p>I am new to python and want to use scrapy to build a web crawler. I go through the tutorial in <a href="http://blog.siliconstraits.vn/building-web-crawler-scrapy/">http://blog.siliconstraits.vn/building-web-crawler-scrapy/</a>. Spider code likes following:</p>
  
  <pre><code>from scrapy.spider         import BaseSpider
  from scrapy.selector         import HtmlXPathSelector
  from nettuts.items        import NettutsItem
  from scrapy.http        import Request
  
  class MySpider(BaseSpider):
       name         = "nettuts"
       allowed_domains    = ["net.tutsplus.com"]
       start_urls    = ["http://net.tutsplus.com/"]
  
  def parse(self, response):
      hxs     = HtmlXPathSelector(response)
      titles     = hxs.select('//h1[@class="post_title"]/a/text()').extract()
      for title in titles:
          item = NettutsItem()
          item["title"] = title
          yield item
  </code></pre>
  
  <p>When launch the spider with command line: scrapy crawl nettus, it has following error:</p>
  
  <pre><code>[boto] DEBUG: Retrieving credentials from metadata server.
  2015-07-05 18:27:17 [boto] ERROR: Caught exception reading instance data
  
  Traceback (most recent call last):
    File "/anaconda/lib/python2.7/site-packages/boto/utils.py", line 210, in retry_url
      r = opener.open(req, timeout=timeout)
  
   File "/anaconda/lib/python2.7/urllib2.py", line 431, in open
  response = self._open(req, data)
  
   File "/anaconda/lib/python2.7/urllib2.py", line 449, in _open
  '_open', req)
  
   File "/anaconda/lib/python2.7/urllib2.py", line 409, in _call_chain
  result = func(*args)
  
   File "/anaconda/lib/python2.7/urllib2.py", line 1227, in http_open
  return self.do_open(httplib.HTTPConnection, req)
  
  File "/anaconda/lib/python2.7/urllib2.py", line 1197, in do_open
  raise URLError(err)
  
  URLError: &lt;urlopen error [Errno 65] No route to host&gt;
  2015-07-05 18:27:17 [boto] ERROR: Unable to read instance data, giving up
  </code></pre>
  
  <p>really do not know what's wrong. Hope somebody could help</p>