Access your ownCloud server from a URL other than localhost

Accessing your owncloud server by pointing your web browser at http(s)://localhost/owncloud is fine, but it means that you have to be using the same computer as the server is running on to get access, which doesn't really feel like the "cloud" at all! If you have your firewall configured to allow access to the machine running the ownCloud server computer from the Internet, then you can access your ownCloud from anywhere.

Let's assume that some-machine.your.domain resolves to the machine running Docker and your ownCloud server and you'd like to get to your server from anywhere by pointing your browser to http(s)://some-machine.your.domain/owncloud. For security purposes, ownCloud only allows access when you visit it though an address in a list of trusted domains. To add some-machine.your.domain to the list of trusted domains, first you must log in as an admin (however you normally do). Once you're logged in, your URL should end in something like /index.php/apps/files/ change it to end in /index.php/settings/admin?trustDomain=some-machine.your.domain
You'll get a message box asking you to verify the addition. After accepting that check, you should be able to access your owncloud server from http(s)://some-machine.your.domain/owncloud

Note that if you wish to use https to access your ownCloud with a URL other than localhost, you'll need to make sure the common name (CN) field in your certificate matches the hostname you're accessing it via.