refactor(infra): directory structure (#4615)

packages/backend/server/src/metrics/controller.ts

@@ -0,0 +1,18 @@
+import { Controller, Get, Res } from '@nestjs/common';
+import type { Response } from 'express';
+import { register } from 'prom-client';
+
+import { PrismaService } from '../prisma';
+
+@Controller()
+export class MetricsController {
+  constructor(private readonly prisma: PrismaService) {}
+
+  @Get('/metrics')
+  async index(@Res() res: Response): Promise<void> {
+    res.header('Content-Type', register.contentType);
+    const prismaMetrics = await this.prisma.$metrics.prometheus();
+    const appMetrics = await register.metrics();
+    res.send(appMetrics + prismaMetrics);
+  }
+}

packages/backend/server/src/metrics/index.ts

@@ -0,0 +1,12 @@
+import { Global, Module } from '@nestjs/common';
+
+import { MetricsController } from '../metrics/controller';
+import { Metrics } from './metrics';
+
+@Global()
+@Module({
+  providers: [Metrics],
+  exports: [Metrics],
+  controllers: [MetricsController],
+})
+export class MetricsModule {}

packages/backend/server/src/metrics/metrics.ts

@@ -0,0 +1,28 @@
+import { Injectable, OnModuleDestroy } from '@nestjs/common';
+import { register } from 'prom-client';
+
+import { metricsCreator } from './utils';
+
+@Injectable()
+export class Metrics implements OnModuleDestroy {
+  onModuleDestroy(): void {
+    register.clear();
+  }
+
+  socketIOEventCounter = metricsCreator.counter('socket_io_counter', ['event']);
+  socketIOEventTimer = metricsCreator.timer('socket_io_timer', ['event']);
+  socketIOConnectionGauge = metricsCreator.gauge(
+    'socket_io_connection_counter'
+  );
+
+  gqlRequest = metricsCreator.counter('gql_request', ['operation']);
+  gqlError = metricsCreator.counter('gql_error', ['operation']);
+  gqlTimer = metricsCreator.timer('gql_timer', ['operation']);
+
+  jwstCodecMerge = metricsCreator.counter('jwst_codec_merge');
+  jwstCodecDidnotMatch = metricsCreator.counter('jwst_codec_didnot_match');
+  jwstCodecFail = metricsCreator.counter('jwst_codec_fail');
+
+  authCounter = metricsCreator.counter('auth');
+  authFailCounter = metricsCreator.counter('auth_fail', ['reason']);
+}

packages/backend/server/src/metrics/utils.ts

@@ -0,0 +1,73 @@
+import { Counter, Gauge, Summary } from 'prom-client';
+
+type LabelValues<T extends string> = Partial<Record<T, string | number>>;
+type MetricsCreator<T extends string> = (
+  value: number,
+  labels: LabelValues<T>
+) => void;
+type TimerMetricsCreator<T extends string> = (
+  labels: LabelValues<T>
+) => () => number;
+
+export const metricsCreatorGenerator = () => {
+  const counterCreator = <T extends string>(
+    name: string,
+    labelNames?: T[]
+  ): MetricsCreator<T> => {
+    const counter = new Counter({
+      name,
+      help: name,
+      ...(labelNames ? { labelNames } : {}),
+    });
+
+    return (value: number, labels: LabelValues<T>) => {
+      counter.inc(labels, value);
+    };
+  };
+
+  const gaugeCreator = <T extends string>(
+    name: string,
+    labelNames?: T[]
+  ): MetricsCreator<T> => {
+    const gauge = new Gauge({
+      name,
+      help: name,
+      ...(labelNames ? { labelNames } : {}),
+    });
+
+    return (value: number, labels: LabelValues<T>) => {
+      gauge.set(labels, value);
+    };
+  };
+
+  const timerCreator = <T extends string>(
+    name: string,
+    labelNames?: T[]
+  ): TimerMetricsCreator<T> => {
+    const summary = new Summary({
+      name,
+      help: name,
+      ...(labelNames ? { labelNames } : {}),
+    });
+
+    return (labels: LabelValues<T>) => {
+      const now = process.hrtime();
+
+      return () => {
+        const delta = process.hrtime(now);
+        const value = delta[0] + delta[1] / 1e9;
+
+        summary.observe(labels, value);
+        return value;
+      };
+    };
+  };
+
+  return {
+    counter: counterCreator,
+    gauge: gaugeCreator,
+    timer: timerCreator,
+  };
+};
+
+export const metricsCreator = metricsCreatorGenerator();