In reply to seankenny:
There's a couple of campsites close to Cassis that I've used. The one in Cassis is a little bit urban but was clean and, obviously, is handy for the Cassis shops/bars/restaurants.
I've also stayed a bit further inland, between Aubagne and Cassis - a much more pleasant venue but a mile or two from either village though I have a feeling there was a restaurant nearby.
There was a great mobile Pizza van that did the rounds of Cassis and Aubagne last time I was there that I can recommend too (not least because he also sold beer!)