The situation in Indonesia is very similar to Malaysia, and I'll quote my own answer to another question, with minor tweaks when applicable:
While you certainly can get drinks and food, most places that stay
open do so a little discreetly, with curtains on the windows etc, and
you'll want to show respect to people who are fasting by not eating,
drinking or smoking in public. The flip side of the coin is that once
the time for buka puasa (breaking the fast) rolls around at sunset,
many restaurants will be packed with Muslims, so you may actually want
to beat the rush and grab your dinner before 6! Out in the nearly 100%
Muslim countryside, though, virtually everything will shut down during
The other travel glitch to beware of is that the end of Ramadan (Eid
ul-Fitr, Idulfitri, or Lebaran in Indonesian) is the local equivalent of
Christmas, when everybody takes time off and goes back to their
families (mudik). This means most transportation is fully booked for several days and even the traffic jams are legendary. Plan ahead so you can
avoid travel at this time.
Note that there's significant regional variation though. As in Malaysia, the Chinese community does not observe Ramadan, so any local Chinatown is a good place to be based. In addition to mainly Hindu Bali, which you already noted, northern Sulawesi around Manado is largely Christian and so are the Batak areas of northern Sumatra. I'd aim to be in one of these areas for the Lebaran rush and the following week; ideally Bali, since it's also got the most to see and do. If you're in a backpacker enclave like the Gili Islands, Ramadan will be more or less invisible.