How to add your sitemap file located in Amazon S3 into Google Webmaster tools #28
Description
Source https://stanicblog.blogspot.hk/2012/02/how-to-add-your-sitemap-file-located-in.html
Once you got your sitemap generated and uploaded to Amazon S3 successfully, you might want to track your sitemap in Google Webmaster Tools as well.
First, add your Amazon S3 site into Google Webmaster Tools. For example, http://s3.amazonaws.com/mybucket/sitemaps
Second, verify your Amazon S3 site by copying the googleXXXXX.html file into your bucket and give the permission accordingly.
Third, go into your Amazon S3 site in Google Webmaster Tools. Navigate to Site Configuration > Sitemaps, add the sitemap located in Amazon S3 for your Rails website.
Done! That All.
Official google blog post on Dealing with Sitemap cross-submissions