In February, we covered the general FAQs for HTTP to HTTPS migrations but now Google's Gary Illyes posted on the Google+ webmaster channel specific FAQs around HTTP to HTTPS migrations for news publishers.
They wrote "We collected a few questions from news publishers related to HTTP to HTTPS site moves, but some of the answers are relevant to all webmasters who are considering going secure."
As you know, I was early to jump on board migrating this news site to HTTPS and I honestly had no issues.
Anyway, here is the Q&A Google published:
Q: How long should I run my trial?
A: Plan for a few weeks to allow for crawling and indexing to pick up changes, plus time to monitor traffic.
Q: Even though we are starting with only a section, we plan to make the entire site available on HTTPS. To avoid indexing of the HTTPS content early, should we use redirects or rel=canonicals?
A: With redirects in place, you won't be able to test those pages from a technical point of view, so we'd recommend using rel=canonical.
Q: We reference our HTTP sitemaps in robots.txt. Should we update the robots.txt to include our new HTTPS sitemaps?
A: We recommend separate robots.txt files for HTTP and HTTPS, pointing to separate sitemap files for HTTP and HTTPS. We also recommend listing a specific URL in only one sitemap file.
Q: Which sitemap should map the section in the HTTPS trial?
A: You can create a separate sitemap just for the updated section of your site. This will enable you to track indexing of the trial section more precisely. Be sure not to duplicate these URLs in any other sitemaps, though.
Q: Are there any other specific things we need to add to the robots.txt for the HTTPS version?
Q: Our HTTPS site redirects non-migrated pages back to HTTP. What should our sitemaps list? Should we list in our sitemaps both the HTTP and HTTPS URLs? What if in the test section the HTTP URLs redirect to HTTPS?
A: List all HTTP URLs in your HTTP sitemap, and all HTTPS URLs in your HTTPS sitemap, regardless of redirects when the user visits the page. Having pages listed in your sitemap regardless of redirects will help search engines discover the new URLs faster.
Q: If we set includeSubDomains in our HSTS header, which domains will that affect?
A: After you migrate your entire site to HTTPS, you can support HSTS preloading for extra security. To enable this, you must set the includeSubDomains directive in the HSTS header.
If the site www.example.com serves an HSTS header with includeSubdomains set, then it will apply to www.example.com and foo.www.example.com, but not example.com or foo.example.com.
Keep in mind however that HSTS adds complexity to your rollback strategy. Our recommendation is this:
1. Roll out HTTPS without HSTS first.
2. Start sending HSTS headers with a short max-age. Monitor your traffic both from users and other clients, and also dependants' performance, such as ads.
3. Slowly increase the HSTS max-age.
If HSTS doesn't affect your users and search engines negatively, you can, if you wish, ask your site to be added to the Chrome HSTS preload list (https://hstspreload.appspot.com/).
Q: We use a single Google News sitemap for our entire site. What do we do if we're migrating our site piece by piece?
A: If you want to use a Google News sitemap for the new HTTPS section, you will have to contact the News team (https://support.google.com/news/publisher/contact/update_domain) to let them know about the protocol change, and then in your HTTPS property in Search Console you can submit a new Google News sitemap (https://support.google.com/news/publisher/answer/74288) for each migrated HTTPS section of the site.
Q: Are there any specific recommendations for Google News Publisher Center (https://partnerdash.google.com/) with HTTPS migration?
A: Google News Publisher Center handles the HTTP->HTTPS moves transparently. In general you don't have to do anything from Google News perspective, unless you're also making use of News sitemaps. In that case, please get in touch with the News team and let them know about the change, https://support.google.com/news/publisher/contact/update_domain. You can also let the team know about changing sections, for example in case you're moving to HTTPS, you can specify that you're moving http://example.com/section to https://example.com/section .
Forum discussion at Google+.