feat: add metrics

package.json

@@ -31,10 +31,12 @@
     "@teacinema/common": "^1.0.0",
     "@teacinema/contracts": "^1.0.0",
     "@teacinema/passport": "^1.0.0",
+    "@willsoto/nestjs-prometheus": "^6.0.2",
     "class-transformer": "^0.5.1",
     "class-validator": "^0.14.3",
     "cookie-parser": "^1.4.7",
     "cross-env": "^10.1.0",
+    "prom-client": "^15.1.3",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1"
   },

src/core/app.module.ts

@@ -5,6 +5,7 @@ import { PassportModule } from '@teacinema/passport'
 import { AccountModule } from '../modules/account/account.module'
 import { AuthModule } from '../modules/auth/auth.module'
 import { UsersModule } from '../modules/users/users.module'
+import { ObservabilityModule } from '../observability/observability.module'
 
 import { AppController } from './app.controller'
 import { AppService } from './app.service'
@@ -20,6 +21,7 @@ import { getPassportConfig } from './config'
         '.env'
       ]
     }),
+    ObservabilityModule,
     AuthModule,
     AccountModule,
     UsersModule,

src/observability/metrics/http-metrics.interceptor.ts

@@ -0,0 +1,62 @@
+import {
+  CallHandler,
+  ExecutionContext,
+  Injectable,
+  NestInterceptor
+} from '@nestjs/common'
+import { InjectMetric } from '@willsoto/nestjs-prometheus'
+import { Request, Response } from 'express'
+import { Counter, Gauge, Histogram } from 'prom-client'
+import { finalize, Observable } from 'rxjs'
+
+@Injectable()
+export class HttpMetricsInterceptor implements NestInterceptor {
+  private readonly SERVICE_NAME: string
+
+  public constructor(
+    @InjectMetric('http_request_duration_seconds')
+    private readonly histogram: Histogram<string>,
+    @InjectMetric('http_requests_in_flight')
+    private readonly inFlight: Gauge<string>,
+    @InjectMetric('http_request_total')
+    private readonly counter: Counter<string>
+  ) {
+    this.SERVICE_NAME = 'gateway'
+  }
+
+  public intercept(
+    context: ExecutionContext,
+    next: CallHandler
+  ): Observable<any> {
+    const req = context.switchToHttp().getRequest<Request>()
+    const res = context.switchToHttp().getResponse<Response>()
+
+    const method = req.method
+    const route = (req.route.path || 'unknown') as string
+
+    this.inFlight.inc({ service: this.SERVICE_NAME })
+
+    const entTimer = this.histogram.startTimer()
+
+    return next.handle().pipe(
+      finalize(() => {
+        const status = res.statusCode.toString()
+        this.counter.inc({
+          service: this.SERVICE_NAME,
+          method,
+          route,
+          status
+        })
+
+        entTimer({
+          service: this.SERVICE_NAME,
+          method,
+          route,
+          status
+        })
+
+        this.inFlight.dec({ service: this.SERVICE_NAME })
+      })
+    )
+  }
+}

src/observability/metrics/metrics.module.ts

@@ -0,0 +1,46 @@
+import { Global, Module } from '@nestjs/common'
+import { APP_INTERCEPTOR } from '@nestjs/core'
+import {
+  makeCounterProvider,
+  makeGaugeProvider,
+  makeHistogramProvider,
+  PrometheusModule
+} from '@willsoto/nestjs-prometheus'
+
+import { HttpMetricsInterceptor } from './http-metrics.interceptor'
+
+@Global()
+@Module({
+  imports: [
+    PrometheusModule.register({
+      path: '/metrics',
+      defaultMetrics: {
+        enabled: true
+      }
+    })
+  ],
+  providers: [
+    makeHistogramProvider({
+      name: 'http_request_duration_seconds',
+      help: 'HTTP request latency',
+      labelNames: ['service', 'method', 'route', 'status'],
+      buckets: [0.05, 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 3, 5]
+    }),
+    makeGaugeProvider({
+      name: 'http_requests_in_flight',
+      help: 'Current number of http requests in flight',
+      labelNames: ['service']
+    }),
+    makeCounterProvider({
+      name: 'http_request_total',
+      help: 'Total http requests',
+      labelNames: ['service', 'method', 'route', 'status']
+    }),
+    HttpMetricsInterceptor,
+    {
+      provide: APP_INTERCEPTOR,
+      useClass: HttpMetricsInterceptor
+    }
+  ]
+})
+export class MetricsModule {}

src/observability/observability.module.ts

@@ -0,0 +1,8 @@
+import { Module } from '@nestjs/common'
+
+import { MetricsModule } from './metrics/metrics.module'
+
+@Module({
+  imports: [MetricsModule]
+})
+export class ObservabilityModule {}

yarn.lock

@@ -1154,6 +1154,11 @@
   dependencies:
     consola "^3.2.3"
 
+"@opentelemetry/api@^1.4.0":
+  version "1.9.0"
+  resolved "https://registry.yarnpkg.com/@opentelemetry/api/-/api-1.9.0.tgz#d03eba68273dc0f7509e2a3d5cba21eae10379fe"
+  integrity sha512-3giAOQvZiH5F9bMlMiv8+GSPMeqg0dbaeo58/0SlA9sxSqZhnUtxzX9/2FzyhS9sWQf5S0GJE0AKBrFqjpeYcg==
+
 "@paralleldrive/cuid2@^2.2.2":
   version "2.3.1"
   resolved "https://registry.yarnpkg.com/@paralleldrive/cuid2/-/cuid2-2.3.1.tgz#3d62ea9e7be867d3fa94b9897fab5b0ae187d784"
@@ -1882,6 +1887,11 @@
     "@webassemblyjs/ast" "1.14.1"
     "@xtuc/long" "4.2.2"
 
+"@willsoto/nestjs-prometheus@^6.0.2":
+  version "6.0.2"
+  resolved "https://registry.yarnpkg.com/@willsoto/nestjs-prometheus/-/nestjs-prometheus-6.0.2.tgz#d603764a923848442ed092411716c0bf211de01f"
+  integrity sha512-ePyLZYdIrOOdlOWovzzMisIgviXqhPVzFpSMKNNhn6xajhRHeBsjAzSdpxZTc6pnjR9hw1lNAHyKnKl7lAPaVg==
+
 "@xtuc/ieee754@^1.2.0":
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/@xtuc/ieee754/-/ieee754-1.2.0.tgz#eef014a3145ae477a1cbc00cd1e552336dceb790"
@@ -2132,6 +2142,11 @@ baseline-browser-mapping@^2.9.0:
   resolved "https://registry.yarnpkg.com/baseline-browser-mapping/-/baseline-browser-mapping-2.9.14.tgz#3b6af0bc032445bca04de58caa9a87cfe921cbb3"
   integrity sha512-B0xUquLkiGLgHhpPBqvl7GWegWBUNuujQ6kXd/r1U38ElPT6Ok8KZ8e+FpUGEc2ZoRQUzq/aUnaKFc/svWUGSg==
 
+bintrees@1.0.2:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/bintrees/-/bintrees-1.0.2.tgz#49f896d6e858a4a499df85c38fb399b9aff840f8"
+  integrity sha512-VOMgTMwjAaUG580SXn3LacVgjurrbMme7ZZNYGSSV7mmtY6QQRh0Eg3pwIcntQ77DErK1L0NxkbetjcoXzVwKw==
+
 bl@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/bl/-/bl-4.1.0.tgz#451535264182bec2fbbc83a62ab98cf11d9f7b3a"
@@ -4453,6 +4468,14 @@ pretty-format@30.2.0, pretty-format@^30.0.0:
     ansi-styles "^5.2.0"
     react-is "^18.3.1"
 
+prom-client@^15.1.3:
+  version "15.1.3"
+  resolved "https://registry.yarnpkg.com/prom-client/-/prom-client-15.1.3.tgz#69fa8de93a88bc9783173db5f758dc1c69fa8fc2"
+  integrity sha512-6ZiOBfCywsD4k1BN9IX0uZhF+tJkV8q8llP64G5Hajs4JOeVLPCwpPVcpXy3BwYiUGgyJzsJJQeOIv7+hDSq8g==
+  dependencies:
+    "@opentelemetry/api" "^1.4.0"
+    tdigest "^0.1.1"
+
 protobufjs@^7.5.3:
   version "7.5.4"
   resolved "https://registry.yarnpkg.com/protobufjs/-/protobufjs-7.5.4.tgz#885d31fe9c4b37f25d1bb600da30b1c5b37d286a"
@@ -4957,6 +4980,13 @@ tapable@^2.2.0, tapable@^2.2.1, tapable@^2.3.0:
   resolved "https://registry.yarnpkg.com/tapable/-/tapable-2.3.0.tgz#7e3ea6d5ca31ba8e078b560f0d83ce9a14aa8be6"
   integrity sha512-g9ljZiwki/LfxmQADO3dEY1CbpmXT5Hm2fJ+QaGKwSXUylMybePR7/67YW7jOrrvjEgL1Fmz5kzyAjWVWLlucg==
 
+tdigest@^0.1.1:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/tdigest/-/tdigest-0.1.2.tgz#96c64bac4ff10746b910b0e23b515794e12faced"
+  integrity sha512-+G0LLgjjo9BZX2MfdvPfH+MKLCrxlXSYec5DaPYP1fe6Iyhf0/fSmJ0bFiZ1F8BT6cGXl2LpltQptzjXKWEkKA==
+  dependencies:
+    bintrees "1.0.2"
+
 terser-webpack-plugin@^5.3.16:
   version "5.3.16"
   resolved "https://registry.yarnpkg.com/terser-webpack-plugin/-/terser-webpack-plugin-5.3.16.tgz#741e448cc3f93d8026ebe4f7ef9e4afacfd56330"