Opening a web link from a snap application

I want to be able to open web URLs from within my snap packaged application. Reading various threads on the forum show that using xdg-open is the way to do this. Just using this command on its own gives a permission denied error. Another thread suggested adding the unity7 interface, with this xdg-open works fine but is it the correct thing to do? Using the unity7 interface seams inappropriate. My app is an opengl game and I previously just had these interfaces:
- x11
- opengl
- network
- pulseaudio
I’m building using Ubuntu 16.04 but obviously want the feature to work for other users too.

Have you tried using desktop and desktop-legacy in place of the unity7 interface?

Looks like desktop works but desktop-legacy fails and gives apparmor=“DENIED” in syslog. I’ll use desktop. Thanks for your help.