I am using a "cloud" hosting provider (Heroku) to host my webapp. Since I don't have access to a permanent file system, I am storing my sitemap.xml in Amazon S3.
I wanted to know the SEO implications of the following 2 options for submitting the sitemap to search engines (Google & Bing) via their webmaster tools:
1) Create on endpoint on my domain: http://mydomain.com/sitemap.xml that performs a 301 redirect to the S3 hosted sitemap. Provide the url hosted on my domain to the search engines. This is the option I am currently using. It seems to work fine with Google, but I noticed a "sitemap error" with Bing - I am monitoring this as I am not yet sure what the cause is.
2) Apparently, there is a way to do "cross domain" sitemap submission whereby I get the S3 URL approved by the search engine, then I can directly submit the S3 url as my sitemap.
Also I am currently pointing the sitemap entry in robots.txt to the sitemap url hosted on my domain (not to S3).
Is one of these methods preferred from an SEO perspective? Like I said, I am using option (1) but I want to be somewhat confident that the crawlers will be OK with the HTTP 301 that I'm using.