Exframe Circuit Breaker module

A standardized circuit breaker abstraction built on top of Opossum

• Opossum npm page
• Opossum type definitions and defaults

Installation

npm install exframe-circuit-breaker

Example

import { CircuitBreaker } from 'exframe-circuit-breaker';

// initialize a breaker
const breaker = new CircuitBreaker(callService, {
    timeoutMs: 10_000,
    resetTimeoutMs: 30_000
});

// register event callback
breaker.on('close', () => {
    console.log('breaker transitioned to closed');
});

breaker.on('open', () => {
    console.log('breaker transitioned to open');
});

// fire the breaker and handle error or rejection
const callServiceWithBreaker = (context, ...args) => breaker.fire(...args).catch(e => {
    const breakerState = breaker.getDebugState(); // debug internal state of breaker; shape is not stable - do not use for control flow

    context.log.warn(e, {breakerState});
    if (e.code === "EOPENBREAKER") {
        // action was rejected due to open circuit
    }
})

Local Dev Notes

• Compiled output from dist
• Unit tests: npm t