README.md

Circuit Breaker Factory

A factory for creating circuit breakers with additional sugar, e.g. state logging.

API

create(config, logger)

Creates a circuit breaker using the provided config. Returns a circuit-breaker-js instance. Please refer to their docs for usage details.

Config

Parameter	Description	Type	Required	Default
source_name	Name of the source, e.g. name of the calling API.	string	Yes
target_name	Name of the target for the circuit breaker, e.g. name of the called API.	string	Yes
window_duration	Duration of statistical rolling window in milliseconds. This is how long metrics are kept for the circuit breaker to use and for publishing. The window is broken into buckets and "roll" by those increments.	number	No	1000
num_buckets	Number of buckets the rolling statistical window is broken into.	number	No	10
timeout_duration	Time in milliseconds after which a command will timeout.	number	No	10000
error_threshold	Error percentage at which the circuit should trip open and start short-circuiting requests to fallback logic.	number	No	50
volume_threshold	Minimum number of requests in rolling window needed before tripping the circuit will occur. For example, if the value is 20, then if only 19 requests are received in the rolling window (say 10 seconds) the circuit will not trip open even if all 19 failed.	number	No	5

Example

var circuit_breaker_factory = require('circuit-breaker-factory');
var config = {
  source_name: 'my-api',
  target_name: 'facebook-graph-api',
  window_duration: 1000,
  num_buckets: 10,
  timeout_duration: 3000,
  error_threshold: 50,
  volume_threshold: 5
};

var breaker = circuit_breaker_factory.create(config, bunyan_logger);
breaker.run(function(success, fail) {
  // do your thing; invoke `success()` for happy cases, `fail()` for sad cases
}, function() {
  // invoked when breaker is open
});