Starting 2019-01-03, GET and HEAD requests to http://tools.wmflabs.org will receive a 301 redirect to https://tools.wmflabs.org. This change should be transparent to most visitors. Some webservices may need to be updated to use explicit https:// or protocol relative URLs for stylesheets, images, JavaScript, and other content that is rendered as part of the pages they serve to their visitors.
More information is posted in out tech blog at: https://phabricator.wikimedia.org/phame/post/view/132/migrating_tools.wmflabs.org_to_https/
If you need some help figuring out how to fix your own tool's output, or to report a tool that needs to be updated, join us in the #wikimedia-cloud IRC channel.
Bryan (on behalf of the Wikimedia Cloud Services team)