For security reasons, ikiwiki.cgi should only be accessed via HTTPS, which is easy to set in the config, however each wiki page contains

<link rel="stylesheet" href="http://ikiwiki.info/style.css" type="text/css" />
<link rel="stylesheet" href="http://ikiwiki.info/local.css" type="text/css" />

regardless of whether the site is accessed via HTTP or HTTPS, which causes most modern browsers to automatically disable javascript and complain about the site only being partially encrypted. Features such as the openID-selector stop working unless the user manually allows the browser to execute unsafe scripts on the site.

This can be fixed by setting the base wiki url to a protocol relative url, such as

//wiki.example.com

but this breaks all sorts of things, like the 404 plugin and wiki rebuilds will throw the following perl warning several times:

Use of uninitialized value in string ne at /usr/share/perl5/IkiWiki.pm line 586

With a vaguely recent ikiwiki, if your url and cgiurl settings have the same hostname (e.g. url => "http://www.example.com", cgiurl => "https://www.example.com/ikiwiki.cgi"), most links are path-only (e.g. /style.css), and in particular, CGI-generated pages should generate those links. This was the implementation of want to avoid ikiwiki using http or https in urls to allow serving both.

This wasn't actually the case if the schemes are different; but now IkiWiki will generate protocol-relative URLs if the CGI is https, the url is http and the hostname is the same (i.e. it assumes that the https equivalent of the url will also work). This is to prevent mixed-content issues, and partially addresses this todo item. --smcv

If your$config{url} and $config{cgiurl} have different hostnames (e.g. url => "http://wiki.example.com", cgiurl => "http://cgi.example.com/ikiwiki.cgi") then you might still have this problem. In principle, IkiWiki could generate protocol-relative URLs in this situation, but it isn't clear to me how widely-supported those are.

HTML5 says protocol-relative URLs work, and they seem to be widely supported in practice, so I've changed the rule to: if the url and cgiurl share a scheme (protocol) but differ only by hostname, use //foo/bar protocol-relative URLs. This partially addresses this todo. I'm still thinking about what the right thing is for more complicated situations: see design for cross-linking between content and CGI. --smcv

If you set both the $config{url} and $config{cgiurl} to https, but make the resulting HTML available over HTTP as well as HTTPS, that should work fine - accesses will be over http until the user either explicitly navigates to https, or navigates to the CGI. --smcv