There's a few threads on here about draft vs draught, but I couldn't find an answer to my question. As a preface, I'm Canadian, and know that draft (US) and draught (UK) are generally interchangeable, but I'm not sure which is correct in Canadian English. As an example for a document we use draft, for a leak in the window we use draught. For what it's worth, I've written draft beer.
According to the Canadian Oxford Dictionary (2nd ed.)*, which is the standard dictionary used by the majority of Canadian editors:
draft beer noun (also esp. Brit. draught beer) beer drawn from a keg, not bottle or canned.
draught beer esp. Brit. var. of DRAFT BEER.
As both spellings are listed, both versions are correct—in other words, either can be used.
This is mostly the same thing as colour versus color. In Canada, colour is the more common spelling, and what would be used in lieu of any specific guidance to the contrary, but color is not actually wrong.
For example, here are those respective entries:
colour (also color)
color etc. var. of COLOUR etc.
Notice how the primary spelling of each word is indicated. If you are looking at a secondary spelling, it will say it's a variant of the all-caps primary spelling. Similarly, if there is nothing shown in all caps, the secondary spelling is listed second. (Also, only the entry for the primary spelling will include actual definition text.)
So, while both draft beer and draught beer are acceptable in Canada, the more common spelling (according to the official dictionary) is draft. Barring specific guidance to the contrary, that's the version that would normally be used.
* Note that I cannot provide links to online entries for this dictionary. I have transcribed these entries from the physical copy on my bookshelf.