Can a snapcraft plugin bring in stage packages and declare plugs?

[Alberto Mardegan]

Hi all!

  I'm working on simplifying the process for creating snaps of webapps.
I've tried building a part, but that doesn't seem to work (see
https://lists.ubuntu.com/archives/snapcraft/2016-December/002186.html --
comments welcome, by the way :-) ).

Now I'm considering achieving the same goal by writing a snapcraft
plugin. Before starting to dig into this, I'd like to know what exactly
can be done by a plugin; in particular, are these tasks feasible?

- Automatically adding stage-packages to the part

- Declaring plugs (like setting up the ubuntu-app-platform plug)


As I understand, the plug definitions are not part of any snapcraft
part, that's why I wonder if a snapcraft plugin (which is usually
attached to a part) can alter them.

Ciao,
  Alberto