Registry / observability / express-metrics-middleware

express-metrics-middleware

library0.1.14jsnpmunverified

Express middleware that automatically collects standard Prometheus metrics (HTTP request duration, request count, active connections, etc.) for Node.js applications. Version 0.1.14 is the current stable release, updated infrequently. Compared to prom-client or express-prom-bundle, this package offers a zero-configuration setup with sensible defaults and built-in TypeScript types. It is opinionated and designed for quick integration without manual metric definition, but may have limited customization options.

observability http-networking web-framework

npm install express-metrics-middleware

package ↗

INSTALL

IMPORT

SIG · EXPRESS-METRICS-MI

express-metrics-middleware

observabilityjavascriptv0.1.14

Install

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Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

createMiddleware

✓ import { createMiddleware } from 'express-metrics-middleware'

✗ import createMiddleware from 'express-metrics-middleware'

Named export, not default. TypeScript types are included.

MetricsConfig

✓ import type { MetricsConfig } from 'express-metrics-middleware'

TypeScript only; use import type for type-only import.

createMiddleware (require)

✓ const { createMiddleware } = require('express-metrics-middleware')

✗ const createMiddleware = require('express-metrics-middleware')

CommonJS: destructure the require because it's a named export.

Shows how to create an Express server with the middleware that collects Prometheus metrics automatically.

import express from 'express'; import { createMiddleware } from 'express-metrics-middleware'; const app = express(); app.use(createMiddleware({ metricPrefix: 'my_app' })); app.get('/hello', (req, res) => { res.send('hello world'); }); app.listen(3000, () => { console.log('Server running on port 3000'); }); // Metrics endpoint is automatically exposed at /metrics by default

Debug

Known issues

gotchaThe middleware exposes a /metrics endpoint by default; ensure it does not conflict with your routes or middleware order (place it before authentication if metrics should be public).

fix

Route /metrics explicitly with your own handler if you need custom behavior.

affects: >=0.1.0

breakingIn version 0.1.0, the function was named 'metricsMiddleware' and exported as default. In 0.1.1+ it changed to named export 'createMiddleware'.

fix

Use import { createMiddleware } from 'express-metrics-middleware' instead.

affects: 0.1.0

gotchaThe middleware relies on prom-client's default metrics (collectDefaultMetrics) which may increase memory usage in long-lived processes. Disable if not needed via options.

fix

Pass { collectDefaultMetrics: false } to createMiddleware.

affects: >=0.1.0

Errors

Common errors & fixes

TypeError: createMiddleware is not a function

Using default import instead of named import.

fix

Use import { createMiddleware } from 'express-metrics-middleware'

Cannot find module 'prom-client' or its corresponding type declarations.

Missing peer dependency prom-client.

fix

Run npm install prom-client

Metrics endpoint returns 404

Middleware not registered or route conflict.

fix

Ensure app.use(createMiddleware()) is called before other routes.

Upgrade

Version history

0.1.14latest on npm

Audit

Dependencies

prom-clientrequiredprovides the Prometheus client library for metrics collection and exposition

expressrequiredExpress is required as it is Express middleware

Agent activity

15 hits · last 30 days

node

OpenAI (training)

Resources

packagehttps://www.npmjs.com/package/express-metrics-middleware ↗