feat: Use options object for all configuration (nodeshift#19)

* BREAKING CHANGE: Options object is now used to configure custom registry and initial circuits

* docs: Updates and adds documentation for options object configuration

README.md

@@ -27,7 +27,7 @@ Example:
   const c2 = new CircuitBreaker(someOtherfunction);
 
   // Provide them to the constructor
-  const prometheus = new PrometheusMetrics([c1, c2]);
+  const prometheus = new PrometheusMetrics({ circuits: [c1, c2] });
 
   //...
   // Provide other circuit breaker later
@@ -58,6 +58,18 @@ const registry = new Registry();
 
 // create a circuit
 const circuit = new CircuitBreaker(functionThatMightFail);
-const metrics = new PrometheusMetrics(circuit, registry)
+const metrics = new PrometheusMetrics({ circuits: [circuit], registry: registry })
 ```
 
+## Options
+The `PrometheusMetrics` constructor takes an options object as detailed below.
+
+```js
+const options = {};
+new PrometheusMetrics(options)
+```
+
+|Name      |Description                                               |Default                                                                                                |
+|----------|----------------------------------------------------------|-------------------------------------------------------------------------------------------------------|
+|`circuits`|A list or individual circuit breaker to create metrics for|No circuits                                                                                            |
+|`registry`|An existing registry to use for prometheus metrics        |`undefined` - The default prometheus registry will be used and default system metrics will be collected|

index.js

@@ -11,13 +11,8 @@ const client = require('prom-client');
 // https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
 
 class PrometheusMetrics {
-  constructor (circuits, registry) {
-    if (circuits instanceof client.Registry) {
-      registry = circuits;
-      circuits = undefined;
-    }
-
-    this._registry = registry || client.register;
+  constructor (options = {}) {
+    this._registry = options.registry || client.register;
     this._client = client;
     this._counter = new this._client.Counter({
       name: `circuit`,
@@ -33,13 +28,13 @@ class PrometheusMetrics {
       labelNames: ['name', 'event']
     });
 
-    if (!registry) {
+    if (!options.registry) {
       this.interval = this._client
         .collectDefaultMetrics({ prefix: 'opossum_', timeout: 5000 });
     }
 
-    if (circuits) {
-      this.add(circuits);
+    if (options.circuits) {
+      this.add(options.circuits);
     }
   }
 

test/prometheus-test.js

@@ -33,7 +33,7 @@ test('The factory function accept no parameter', t => {
 test('The factory function takes an object instead of just an Array', async t => {
   t.plan(3);
   const c1 = new CircuitBreaker(passFail, { name: 'fred' });
-  const prometheus = new PrometheusMetrics(c1);
+  const prometheus = new PrometheusMetrics({ circuits: c1 });
   await c1.fire(1);
   t.equal(c1.name, 'fred');
   t.ok(/circuit.*fred/.test(prometheus.metrics));
@@ -47,7 +47,7 @@ test('The factory function provides access to metrics for all circuits',
     t.plan(6);
     const c1 = new CircuitBreaker(passFail, { name: 'fred' });
     const c2 = new CircuitBreaker(passFail, { name: 'bob' });
-    const prometheus = new PrometheusMetrics([c1, c2]);
+    const prometheus = new PrometheusMetrics({ circuits: [c1, c2] });
     await c1.fire(1);
     await c2.fire(1);
     t.equal(c1.name, 'fred');
@@ -69,7 +69,10 @@ test('The factory function uses a custom prom-client registry', async t => {
   const c2 = new CircuitBreaker(passFail, {
     name: 'bob'
   });
-  const prometheus = new PrometheusMetrics([c1, c2], registry);
+  const prometheus = new PrometheusMetrics({
+    circuits: [c1, c2],
+    registry: registry
+  });
   await c1.fire(1);
   await c2.fire(1);
   t.equal(c1.name, 'fred');
@@ -105,7 +108,7 @@ test('The add function provides access to metrics for all circuits',
     const c1 = new CircuitBreaker(passFail, { name: 'fred' });
     const c2 = new CircuitBreaker(passFail, { name: 'bob' });
     const c3 = new CircuitBreaker(passFail, { name: 'foo' });
-    const prometheus = new PrometheusMetrics([c1]);
+    const prometheus = new PrometheusMetrics({ circuits: [c1] });
     prometheus.add([c2, c3]);
     await c1.fire(1);
     await c2.fire(1);
@@ -137,7 +140,7 @@ test('Circuit fire/success/failure are counted', t => {
   const fire = /circuit\{name="passFail",event="fire"\} 2/;
   const success = /circuit\{name="passFail",event="success"\} 1/;
   const failure = /circuit\{name="passFail",event="failure"\} 1/;
-  const prometheus = new PrometheusMetrics([circuit]);
+  const prometheus = new PrometheusMetrics({ circuits: [circuit] });
   t.plan(3);
   circuit.fire(1)
     .then(_ => circuit.fire(-1))
@@ -156,7 +159,7 @@ test('Metrics are enabled for all circuit events', t => {
   circuit.on = (event, callback) => {
     callback(null, 1);
   };
-  const prometheus = new PrometheusMetrics([circuit]);
+  const prometheus = new PrometheusMetrics({ circuits: [circuit] });
   const metrics = prometheus.metrics;
   t.plan(circuit.eventNames().length);
   for (const name of circuit.eventNames()) {
@@ -169,7 +172,7 @@ test('Metrics are enabled for all circuit events', t => {
 
 test('Default prometheus metrics are enabled', t => {
   const circuit = new CircuitBreaker(passFail);
-  const prometheus = new PrometheusMetrics([circuit]);
+  const prometheus = new PrometheusMetrics({ circuits: [circuit] });
   const metrics = prometheus.metrics;
   const names = [
     'process_cpu_seconds_total',
@@ -192,7 +195,10 @@ test('Default prometheus metrics are enabled', t => {
 test('Should not add default metrics to custom registry', t => {
   const registry = new Registry();
   const circuit = new CircuitBreaker(passFail);
-  const prometheus = new PrometheusMetrics([circuit], registry);
+  const prometheus = new PrometheusMetrics({
+    circuits: [circuit],
+    registry: registry
+  });
   const metrics = prometheus.metrics;
   const names = [
     'process_cpu_seconds_total',
@@ -214,7 +220,7 @@ test('Should not add default metrics to custom registry', t => {
 
 test('Default prometheus metrics are enabled without circuit', t => {
   const registry = new Registry();
-  const prometheus = new PrometheusMetrics(registry);
+  const prometheus = new PrometheusMetrics({ registry: registry });
   const metrics = prometheus.metrics;
   const names = [
     'nodejs_eventloop_lag',
@@ -246,7 +252,7 @@ test('Default prometheus metrics are enabled without circuit', t => {
 
 test('Node.js specific metrics are enabled', t => {
   const circuit = new CircuitBreaker(passFail);
-  const prometheus = new PrometheusMetrics([circuit]);
+  const prometheus = new PrometheusMetrics({ circuits: [circuit] });
   const metrics = prometheus.metrics;
   const names = [
     'nodejs_eventloop_lag',