Compost piles getting warmer is a good indicator that the waste is breaking down and your compost is being made.
The warm compost is a result of the organisms breaking down the organic matter which is a good thing.
If your compost pile or compost is not getting warm then it may not be composting properly.
You have to make sure to work your compost and turn it over often.
The reasons that compost piles get warmer and hotter is due to the activity of numerous organisms breaking down organic matter.
As the organic matter breaks down due to the organisms the compost piles heat up and get warmer which is a good thing and when your compost pile gets warmer it's a good sign that the compost is working properly.
When your compost pile is doing it's job and getting hot enough the compost pile can reach at least 130°F in temperature which is a good thing.
If the compost pile is not getting hot enough then the compost pile is likely not doing good and you need to be sure to turn the compost over and don't put the wrong things in the compost pile which can affect it as well.
Rats and mice are indeed attracted to compost piles since they contain food and rats and mice do look for food and can smell it.
You can set out mouse traps or rat traps near the compost bins to trap and kill rats and mice to keep them away from the compost bin.
Keeping the compost bin covered to prevent the smell of the food from the compost bin can help keep mice and rats away from your compost bin too.
Also leave out meat because meat creates a smell that easily attracts rats and mice so by keeping meat out of the compost bin will lessen the attraction of rats.
You should also keep your compost pile or bin in a dry, shady spot with a convenient water source nearby and the rats and mice will usually stay away.