luci/applications/luci-app-radicale2/luasrc/view/cbi/raduigo.htm

<%
local uci  = require "luci.model.uci".cursor()
local http_port = uci:get("radicale2", "server", "host")
local usessl = uci:get_bool("radicale2", "server", "ssl")
if type(http_port) == "table" then
        http_port = http_port[1]
end

	if http_port then
	        http_port = http_port:match("(%d+)$")
	end
	if not http_port then
		http_port = "5232"
	end
%>
<script type="text/javascript">
<%
if usessl then
%>
	var protocol = 'https'
<% else %>
	var protocol = 'http'
<% end %>
document.write('<a href="' + protocol + '://' + window.location.hostname + ':' + <%=http_port%> + '/"><%=luci.i18n.translate("Go to Radicale 2.x Web UI")%></a>');
</script>