Do Canadian officeholders take an oath of office? To whom and by whom do they swear?

I'm constantly bemused by how much - and sometimes, how little- has been retained from countries of origin. (As a total aside, one of the bits of law that we in the US allegedly kept from Britain is the one that gives ownership of disputed land to the one who has it in its possession and use, even when the owner paying taxes on it didn't know the neighbor had encroached upon it.)