In Azure, there is a component to monitor the number of requests made to each Azure Function in real time. This component is called the scale controller. It collects data and then later makes a decision to scale the number of instances up or down for that function. Azure has the concept of an app service. A function app may contain many instances of a function.

All decision making is based on heuristic-based algorithms for different types of event triggers. When the function is scaled out, all resources related to that function will also be scaled out. The number of function instances will be automatically scaled down to zero, if there is no request made to the function app.