Mastering Python Design Patterns - Second Edition

Implementation

We are going to use the pybreaker library. You can install it in your Python, via the pip install pybreaker command.

Let's say you want to use a circuit breaker on a flaky function (for example, fragile due to the networking environment it depends on).

Our implementation is inspired by a nice script I found in this repository: https://github.com/veltra/pybreaker-playground, which we will adapt.

Here is our version of the function to simulate fragile calls:

def fragile_function():    if not random.choice([True, False]):        print(' / OK', end='')    else:        print(' / FAIL', end='')        raise Exception('This is a sample Exception')

Let's define our cirbuit breaker to automatically open the circuit after five consecutive failures in that function. ...