clue/docker-ttrss — pull request #12 by jap (2014-12-31 21:02:34+00:00)
Title: Install php5-mcrypt as well.

Installing php5-mcrypt seems to be required:

4 docker exec ttrss_main tail -n1 /tmp/ttrss-update-daemon.stderr
PHP Fatal error: Call to undefined function mcrypt_decrypt() in /var/www/include/crypt.php on line 12