[[!comment format=mdwn
 username="smcv"
 subject="Protocol-relative URLs are not always an option; change your url and cgiurl settings"
 date="2015-12-13T22:20:13Z"
 content="""
IkiWiki already uses relative (`../foo/`), hostname-relative (`/foo`) or
protocol-relative (`//example.com/foo/`) URLs wherever it can. However, not
everything is allowed to be relative: in particular, more or less
everything in RSS has to be absolute, either because the specification says so,
or because in practice RSS consumers usually get relative URLs wrong.
When we generated XHTML 1.0, `<base href=... />` had to be absolute too,
but now that we always generate HTML 5 it's relative, so RSS is one of the
few places the full `url` and `cgiurl` are used.

If you have a certificate that's trusted by \"normal\" browsers (like LetsEncrypt),
then there's no disadvantage in changing your `url` and `cgiurl` to
both be `https://...`, and rebuilding your wiki. At this point I would only
recommend using plain `http://` if you either have no certificate, or a
self-signed or otherwise not-universally-trusted certificate for a non-public
website.

Because IkiWiki mostly outputs relative URLs, accesses via `http` will stay
on `http`, unless you also reconfigure your web server (not specific to
IkiWiki, for instance if you use Apache see
[RedirectSSL on the Apache wiki](https://wiki.apache.org/httpd/RedirectSSL).
"""]]