Announcements - silinternational/ssp-base GitHub Wiki
An announcement can be displayed on the Hub's discovery page or an IDP's login page based on the contents of /data/vendor/simplesamlphp/simplesamlphp/announcement/announcement.php.
This file can return a string or an array with an "announcement_text" entry. If it returns an array with either or both of these entries ("start_datetime", "end_datetime"), they will be used to determine whether to actually display the announcement based on the current date.
The announcement text may contain html and will not be escaped or validated.