Memcache is a requirement (tested only with APCu). Install php-apcu, php5-apcu, or whatever this package is called on your Linux distro, and add the following line to owncloud/config/config.php:
You need to configure the WOPI Client URL, which is where the LibreOffice Online WebSocket Daemon (loolwsd) is listening. It is in Admin - Collabora Online section in ownCloud, or you can set it from command line:
Default port is 9980. If loolwsd was compiled without SSL (like in the [CODE VM](https://collaboraoffice.com/code/)), you have to write `http` instead of `https`. If you use SSL, and you get the following error:
cURL error 60: SSL certificate problem: self signed certificate in certificate chain
You have to add the CA cert manually to ownCloud trusted cert storage: