express-prom-bundle/types/index.test-d.ts

import express, { RequestHandler } from 'express';
import { expectType } from 'tsd'
import * as promClient from 'prom-client';
import promBundle, {
  type Middleware
} from '..';

const middleware: express.RequestHandler = promBundle({ includeMethod: true });

expectType<string>(middleware.name);

promClient.register.clear();

expectType<Middleware>(promBundle({
  normalizePath: [
    // collect paths like "/customer/johnbobson" as just one "/custom/#name"
    ['^/customer/.*', '/customer/#name'],

    // collect paths like "/bobjohnson/order-list" as just one "/#name/order-list"
    ['^.*/order-list', '/#name/order-list']
  ],
  urlValueParser: {
    minHexLength: 5,
    extraMasks: [
      'ORD[0-9]{5,}' // replace strings like ORD1243423, ORD673562 as #val
    ]
  }
}));

promClient.register.clear();

expectType<Middleware>(promBundle({
  buckets: [0.1, 0.4, 0.7],
  includeMethod: true,
  includePath: true,
  excludeRoutes: ['/foo', /^\/bar\/?$/],
  customLabels: { year: null },
  transformLabels: (labels: promBundle.Labels) => ({
    ...labels,
    year: new Date().getFullYear()
  }),
  metricType: 'histogram',
  metricsPath: '/prometheus',
  promClient: {
    collectDefaultMetrics: {
    }
  },
  promRegistry: new promClient.Registry(),
  urlValueParser: {
    minHexLength: 5,
    extraMasks: [
      '^[0-9]+\\.[0-9]+\\.[0-9]+$' // replace dot-separated dates with #val
    ]
  },
  normalizePath: [
    ['^/foo', '/example'] // replace /foo with /example
  ],
  formatStatusCode: (res: express.Response) => res.statusCode + 100,
  metricsApp: express()
}));

promClient.register.clear();

promBundle({
  metricType: 'summary',
  maxAgeSeconds: 600,
  ageBuckets: 5
});

promClient.register.clear();

promBundle({
  metricType: 'summary',
  percentiles: [0.01, 0.1, 0.9, 0.99]
});

// TypeScript workaround to write a readonly field
type Writable<T> = { -readonly [K in keyof T]: T[K] };
const wPromBundle: Writable<promBundle> = promBundle;

wPromBundle.normalizePath = (req: express.Request, opts: promBundle.Opts) => {
  const path = promBundle.normalizePath(req, opts);

  // count all docs as one path, but /docs/login as a separate one
  return path.match(/^\/docs/) && !path.match(/^\/login/) ? '/docs/*' : path;
};

wPromBundle.normalizeStatusCode = (res: express.Response) => res.statusCode.toString();

expectType<RequestHandler>(promBundle.clusterMetrics());