SymfonyCloud includes an additional X-Robots-Tag header on all non-production environments:

X-Robots-Tag: noindex, nofollow

That tells search engines to not index sites on non-production environments entirely nor traverse links from those sites, even if they are publicly visible. That keeps non-production sites out of search engine indexes that would dilute the SEO of the production site.

On a production instance (the master branch, after a domain has been assigned) the search-blocker is disabled and your application can serve a robots.txt file as normal.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.