feat: support histogram and summary

Author: netanelavr

src/interfaces.ts

@@ -1,4 +1,4 @@
 export interface MetricsConfig {
-     defaultLabels?: Record<string, string>;
-     defaultMetricsEnabled?: boolean;
+	defaultLabels?: Record<string, string>;
+	defaultMetricsEnabled?: boolean;
 }

src/metrics/metrics.controller.ts

@@ -1,15 +1,15 @@
 import { Controller, Get } from '@nestjs/common';
 import { Registry } from 'prom-client';
-import { ApiTags } from '@nestjs/swagger';
+import { ApiOperation, ApiTags } from '@nestjs/swagger';
 
 @ApiTags( 'Metrics' )
 @Controller( 'metrics' )
 export class MetricsController {
-	constructor( private readonly registry: Registry ) {
-	}
-     
-     @Get()
-	async getMetrics() {
+	constructor( private readonly registry: Registry ) {}
+	
+	@Get()
+	@ApiOperation( { summary: 'Get Prometheus metrics' } )
+	async getMetrics(): Promise<string> {
 		return await this.registry.metrics();
 	}
 }

src/metrics/metrics.service.ts

@@ -1,14 +1,15 @@
 import { Inject, Injectable } from '@nestjs/common';
-import { Counter, Gauge, Registry } from 'prom-client';
+import { Counter, Gauge, Histogram, Registry, Summary } from 'prom-client';
 
 @Injectable()
 export class MetricsService {
 	private readonly counter: { [ key: string ]: Counter<string> } = {};
 	private readonly gauge: { [ key: string ]: Gauge<string> } = {};
-     
-	constructor( @Inject( Registry ) private readonly registry: Registry ) {
-	}
-     
+	private readonly histogram: { [ key: string ]: Histogram<string> } = {};
+	private readonly summary: { [ key: string ]: Summary<string> } = {};
+	
+	constructor( @Inject( Registry ) private readonly registry: Registry ) {}
+	
 	public incCounter( key: string, labels?: Record<string, string | number> ): void {
 		if ( ! this.counter[ key ] ) {
 			this.counter[ key ] = new Counter( {
@@ -20,7 +21,7 @@ export class MetricsService {
 		}
 		this.counter[ key ].inc( labels || {} );
 	}
-     
+	
 	public setGauge( key: string, value: number, labels?: Record<string, string | number> ): void {
 		if ( ! this.gauge[ key ] ) {
 			this.gauge[ key ] = new Gauge( {
@@ -32,4 +33,40 @@ export class MetricsService {
 		}
 		this.gauge[ key ].set( labels || {}, value );
 	}
+	
+	public observeHistogram(
+		key: string,
+		value: number,
+		labels?: Record<string, string | number>,
+		buckets?: number[]
+	): void {
+		if ( ! this.histogram[ key ] ) {
+			this.histogram[ key ] = new Histogram( {
+				name: key,
+				help: `Histogram for ${ key }`,
+				labelNames: labels ? Object.keys( labels ) : [],
+				buckets: buckets || [ 0.1, 0.5, 1, 2, 5 ],
+				registers: [ this.registry ],
+			} );
+		}
+		this.histogram[ key ].observe( labels || {}, value );
+	}
+	
+	public observeSummary(
+		key: string,
+		value: number,
+		labels?: Record<string, string | number>,
+		percentiles?: number[]
+	): void {
+		if ( ! this.summary[ key ] ) {
+			this.summary[ key ] = new Summary( {
+				name: key,
+				help: `Summary for ${ key }`,
+				labelNames: labels ? Object.keys( labels ) : [],
+				percentiles: percentiles || [ 0.01, 0.05, 0.5, 0.9, 0.95, 0.99 ],
+				registers: [ this.registry ],
+			} );
+		}
+		this.summary[ key ].observe( labels || {}, value );
+	}
 }

src/reporter/reporter.service.ts

@@ -4,34 +4,71 @@ import { MetricsService } from '../metrics/metrics.service';
 export class ReporterService {
 	private static readonly logger = new Logger( ReporterService.name );
 	private static metricsService: MetricsService;
-     
+	
 	static init( metricsService: MetricsService ): void {
 		ReporterService.metricsService = metricsService;
 	}
-     
-	static counter( key: string, labels?: Record<string, string | number> ): void {
+	
+	static counter(
+		key: string,
+		labels?: Record<string, string | number>
+	): void {
 		this.validateMetricsService();
-
+		
 		try {
 			ReporterService.metricsService.incCounter( key, labels );
 		} catch ( error ) {
 			this.logger.error( `Error while incrementing counter - ${ key }`, error );
 		}
 	}
-     
-	static gauge( key: string, value: number, labels?: Record<string, string | number> ): void {
+	
+	static gauge(
+		key: string,
+		value: number,
+		labels?: Record<string, string | number>
+	): void {
 		this.validateMetricsService();
-
+		
 		try {
 			ReporterService.metricsService.setGauge( key, value, labels );
 		} catch ( error ) {
 			this.logger.error( `Error while setting gauge - ${ key }, ${ value }`, error );
 		}
 	}
 
+	static histogram(
+		key: string,
+		value: number,
+		labels?: Record<string, string | number>,
+		buckets?: number[]
+	): void {
+		this.validateMetricsService();
+		
+		try {
+			ReporterService.metricsService.observeHistogram( key, value, labels, buckets );
+		} catch ( error ) {
+			this.logger.error( `Error while observing histogram - ${ key }, ${ value }`, error );
+		}
+	}
+	
+	static summary(
+		key: string,
+		value: number,
+		labels?: Record<string, string | number>,
+		percentiles?: number[]
+	): void {
+		this.validateMetricsService();
+		
+		try {
+			ReporterService.metricsService.observeSummary( key, value, labels, percentiles );
+		} catch ( error ) {
+			this.logger.error( `Error while observing summary - ${ key }, ${ value }`, error );
+		}
+	}
+	
 	private static validateMetricsService(): void {
-		if (!ReporterService.metricsService) {
-			throw new Error('MetricsService is not initialized.');
+		if ( ! ReporterService.metricsService ) {
+			throw new Error( 'MetricsService is not initialized.' );
 		}
 	}
 }