If you are doing only a single or just a few prints, go for a spray can.
Coating canvas with a roller or brush can lead to a lot of frustration and no small number of ruined prints. It should be easy...but it's not! It is oh-so-easy to peel up little bits of the image. Others here can share tales of woe to back me up on this. Certain individuals endowed with powers far beyond those of mortal man can handle it, they are a rare breed. Spray cans are expensive for routine use but will usually lead to a first-try success for a canvas newbie.