Here is the simplest cranberry soda, made from adding some of the cheapest economy size bread yeast to a half gallon jug of cran drink. Nothing else added or any transfer of containers.
It should come in a plastic jug and can be generic or store brands which are getting surprisingly good when simple and pure. Cran rasberry (normally my least favorite) or straight cran seems to work best... the other combos like cran apple, grape, etc don't emerge from the yeast as tasty.
The trick that distinguishes this from cider is to just give an initial blush of fast fermentation for bubble pressure... preserving sweetness, then consume it soon. Assuming the juice came with no artificial sweetener (yuk!) and little or no natural added sugar, i open the room temp jug and quickly pour in a mound of yeast about the size of three stacked large coins. I loosely recap, squeeze out most air, then tightly cap.
I let it sit for a few hours until the container is quite bloated and hard. Watch it because its hard to believe it wont blast a cap off, although never happened to me. If you like it warm, try it after bleeding pressure by a few quick opening and closings of the cap. Or else stick in fridge where it will shrink then reinflate in a few hours. It's quite intense flavor and bubbles; I guess you could pour it into a glass containing some water.
After opening, the trick is to squeeze out all possible air before resealing. You will hear it reflate noisely even in the fridge. When you finally cant flatten all remaining air out, prepare to accept a lot of off flavors from random yeast. They only go away if you leave it to turn quite alcoholic. Silly me, i dislike alcohol and swirl result into a half full jar of applesauce which resweetens it and gives crazy suspended bubbles in the resulting delicious slurry.