title: Using one Scrapy spider for several websites
body: <p>I need to create a user configurable web spider/crawler, and I'm thinking about using Scrapy. But, I can't hard-code the domains and allowed URL regex:es -- this will instead be configurable in a GUI.</p>
  
  <p>How do I (as simple as possible) create a spider or a set of spiders with Scrapy where the domains and allowed URL regex:es are dynamically configurable? E.g. I write the configuration to a file, and the spider reads it somehow.</p>