feat: impact metric flag context (#749)

Author: kwasniew

src/impact-metrics/metric-client.ts

@@ -1,11 +1,13 @@
 import { EventEmitter } from 'stream';
 import { StaticContext, Unleash, UnleashEvents } from '../unleash';
-import { ImpactMetricRegistry } from './metric-types';
+import { ImpactMetricRegistry, MetricFlagContext, MetricLabels } from './metric-types';
 import { extractEnvironmentFromCustomHeaders } from './environment-resolver';
+import Client from '../client';
 
 export class MetricsAPI extends EventEmitter {
   constructor(
     private metricRegistry: ImpactMetricRegistry,
+    private variantResolver: Pick<Client, 'forceGetVariant'>,
     private staticContext: StaticContext,
   ) {
     super();
@@ -29,7 +31,25 @@ export class MetricsAPI extends EventEmitter {
     this.metricRegistry.gauge({ name, help, labelNames });
   }
 
-  incrementCounter(name: string, value?: number, featureName?: string): void {
+  private getFlagLabels(flagContext?: MetricFlagContext): MetricLabels {
+    let flagLabels: MetricLabels = {};
+    if (flagContext) {
+      for (const flag of flagContext.flagNames) {
+        const variant = this.variantResolver.forceGetVariant(flag, flagContext.context);
+
+        if (variant.enabled) {
+          flagLabels[flag] = variant.name;
+        } else if (variant.feature_enabled) {
+          flagLabels[flag] = 'enabled';
+        } else {
+          flagLabels[flag] = 'disabled';
+        }
+      }
+    }
+    return flagLabels;
+  }
+
+  incrementCounter(name: string, value?: number, flagContext?: MetricFlagContext): void {
     const counter = this.metricRegistry.getCounter(name);
     if (!counter) {
       this.emit(
@@ -39,23 +59,27 @@ export class MetricsAPI extends EventEmitter {
       return;
     }
 
+    const flagLabels = this.getFlagLabels(flagContext);
+
     const labels = {
-      ...(featureName ? { featureName } : {}),
+      ...flagLabels,
       ...this.staticContext,
     };
 
     counter.inc(value, labels);
   }
 
-  updateGauge(name: string, value: number, featureName?: string): void {
+  updateGauge(name: string, value: number, flagContext?: MetricFlagContext): void {
     const gauge = this.metricRegistry.getGauge(name);
     if (!gauge) {
       this.emit(UnleashEvents.Warn, `Gauge ${name} not defined, this gauge will not be updated.`);
       return;
     }
 
+    const flagLabels = this.getFlagLabels(flagContext);
+
     const labels = {
-      ...(featureName ? { featureName } : {}),
+      ...flagLabels,
       ...this.staticContext,
     };
 
@@ -79,6 +103,6 @@ export class UnleashMetricClient extends Unleash {
       }
     }
 
-    this.impactMetrics = new MetricsAPI(this.metricRegistry, metricsContext);
+    this.impactMetrics = new MetricsAPI(this.metricRegistry, this.client, metricsContext);
   }
 }

src/impact-metrics/metric-types.ts

@@ -1,3 +1,5 @@
+import { Context } from '../context';
+
 type MetricType = 'counter' | 'gauge';
 type LabelValuesKey = string;
 
@@ -195,3 +197,8 @@ export interface MetricOptions {
   help: string;
   labelNames?: string[];
 }
+
+export interface MetricFlagContext {
+  flagNames: string[];
+  context: Context;
+}

src/test/impact-metrics/metric-client.test.ts

@@ -1,6 +1,20 @@
 import { MetricsAPI } from '../../impact-metrics/metric-client';
 
 import test from 'ava';
+import Client from '../../client';
+import { MetricLabels } from '../../impact-metrics/metric-types';
+
+const fakeVariantResolver = (
+  variantName = 'disabled',
+  feature_enabled = true,
+): Pick<Client, 'forceGetVariant'> => ({
+  forceGetVariant: () => ({
+    name: variantName,
+    feature_enabled,
+    enabled: variantName !== 'disabled',
+    featureEnabled: feature_enabled,
+  }),
+});
 
 test('should not register a counter with empty name or help', (t) => {
   let counterRegistered = false;
@@ -12,7 +26,7 @@ test('should not register a counter with empty name or help', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
   api.defineCounter('some_name', '');
   t.false(counterRegistered, 'Counter should not be registered with empty help');
@@ -31,7 +45,7 @@ test('should register a counter with valid name and help', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
   api.defineCounter('valid_name', 'Valid help text');
   t.true(counterRegistered, 'Counter should be registered with valid name and help');
@@ -47,7 +61,7 @@ test('should not register a gauge with empty name or help', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
   api.defineGauge('some_name', '');
   t.false(gaugeRegistered, 'Gauge should not be registered with empty help');
@@ -66,18 +80,20 @@ test('should register a gauge with valid name and help', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
   api.defineGauge('valid_name', 'Valid help text');
   t.true(gaugeRegistered, 'Gauge should be registered with valid name and help');
 });
 
 test('should increment counter with valid parameters', (t) => {
   let counterIncremented = false;
+  let recordedLabels: MetricLabels = {};
 
   const fakeCounter = {
-    inc: () => {
+    inc: (_value: number, labels: MetricLabels) => {
       counterIncremented = true;
+      recordedLabels = labels;
     },
   };
 
@@ -86,18 +102,21 @@ test('should increment counter with valid parameters', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
-  api.incrementCounter('valid_counter', 5, 'featureX');
+  api.incrementCounter('valid_counter', 5, { flagNames: ['featureX'], context: staticContext });
   t.true(counterIncremented, 'Counter should be incremented with valid parameters');
+  t.deepEqual(recordedLabels, { appName: 'my-app', environment: 'dev', featureX: 'enabled' });
 });
 
 test('should set gauge with valid parameters', (t) => {
   let gaugeSet = false;
+  let recordedLabels: MetricLabels = {};
 
   const fakeGauge = {
-    set: () => {
+    set: (_value: number, labels: MetricLabels) => {
       gaugeSet = true;
+      recordedLabels = labels;
     },
   };
 
@@ -106,10 +125,11 @@ test('should set gauge with valid parameters', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver('variantY'), staticContext);
 
-  api.updateGauge('valid_gauge', 10, 'featureY');
+  api.updateGauge('valid_gauge', 10, { flagNames: ['featureY'], context: staticContext });
   t.true(gaugeSet, 'Gauge should be set with valid parameters');
+  t.deepEqual(recordedLabels, { appName: 'my-app', environment: 'dev', featureY: 'variantY' });
 });
 
 test('defining a counter automatically sets label names', (t) => {
@@ -127,7 +147,7 @@ test('defining a counter automatically sets label names', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver(), staticContext);
 
   api.defineCounter('test_counter', 'Test help text');
   t.true(counterRegistered, 'Counter should be registered');
@@ -148,7 +168,7 @@ test('defining a gauge automatically sets label names', (t) => {
   };
 
   const staticContext = { appName: 'my-app', environment: 'dev' };
-  const api = new MetricsAPI(fakeRegistry as any, staticContext);
+  const api = new MetricsAPI(fakeRegistry as any, fakeVariantResolver('variantX'), staticContext);
 
   api.defineGauge('test_gauge', 'Test help text');
   t.true(gaugeRegistered, 'Gauge should be registered');

src/unleash.ts

@@ -41,7 +41,7 @@ export class Unleash extends EventEmitter {
 
   private repository: RepositoryInterface;
 
-  private client: Client;
+  protected client: Client;
 
   private metrics: Metrics;