Prometheus integration for Nuxt

Prometheus metrics for your Nuxt server. See how long each route takes, how much time goes to outbound calls, and which status code each route returns. Nuxt 2 users can use this version.

Why you want it

• Route timings with a status_code label. You can separate slow responses from errors.
• Histograms for request, render and total time. They work with histogram_quantile() in Grafana.
• Outbound call timings without network interception. HTTP/2 and gRPC keep working and are still counted.
• A Grafana dashboard with a Docker Compose stack.
• A health check route for your load balancer.

Supported stack

Routes

You can change both paths with the module options.

Installation

Install the package with a package manager:

# using nuxi, it automatically appends the module in your nuxt.config
npx nuxi@latest module add prometheus

# using npm
npm install @artmizu/nuxt-prometheus

# using yarn
yarn add @artmizu/nuxt-prometheus

# using pnpm
pnpm add @artmizu/nuxt-prometheus

Add the module to the modules section of your Nuxt config:

export default {
  modules: ['@artmizu/nuxt-prometheus']
}

Upgrading to 4.0.0

1. Use Node.js 22 (22.22.3+), 24 (24.15.0+), or 26+.
2. Update @artmizu/nuxt-prometheus to 4.0.0.

3. If you register custom metrics, replace prom-client with @prometheus-io/client in your dependencies and imports:

   import { Counter, register } from '@prometheus-io/client'

4. Update dashboard queries to use histograms. Use histogram_quantile() for percentiles.

5. Add status_code to all page timing metric queries and dashboards. All six page metrics now include a status_code label:

   sum by (path) (
     rate(page_total_time_histogram_count{status_code=~"5.."}[5m])
   ) /
   sum by (path) (
     rate(page_total_time_histogram_count[5m])
   )

Grafana dashboard

A ready-to-use dashboard lives in examples/grafana, together with a Docker Compose stack that starts Prometheus and Grafana with the dashboard already provisioned.

See examples/grafana/README.md for the import steps, the queries behind each panel, and how to point Prometheus at your app.

Collected Metrics

In addition to the default Node.js metrics provided by @prometheus-io/client, this module collects the following custom metrics:

All custom metric names can be prefixed with the prefix option, for example myapp_page_render_time.

The page_request_time metrics include outbound fetch, http, https, HTTP/2 and gRPC calls. They do not include raw TCP connections or database clients.

Histograms export _bucket, _sum, and _count series. The +Inf bucket is automatic.

The gauge variants keep the last observed value per (path, status_code) pair and never expire, so a path that rarely returns an error can appear to have a stale sample; use the histograms for aggregation and dashboards.

SSR error renders and unmatched-route 404s are attributed to the synthetic /__nuxt_error path with their real status code, so per-page error rates cannot be derived from path. A path with no 5xx samples is absent from an error-ratio query rather than showing 0.

For the p95 total duration across replicas, in milliseconds:

histogram_quantile(0.95, sum by (le, path) (rate(page_total_time_histogram_bucket[5m])))

Options

You can pass it through module options and the nuxt config property prometheus.

enabled

• Type: boolean
• Default: true
• Description: Enables or disables Prometheus integration at runtime. When set to false, no metrics are collected and no hooks are registered. This allows you to build the app with the module but disable it in certain environments.

verbose

• Type: boolean
• Default: true
• Description: Additional logs in the dev mode, about page rendering time and time of external API requests

healthCheck

• Type: boolean
• Default: true
• Description: To turn on and off the healthcheck route

healthCheckPath

• Type: string
• Default: /health
• Description: Healthcheck url path

prometheusPath

• Type: string
• Default: /metrics
• Description: Prometheus exporter url path

prefix

• Type: string
• Default: no prefix
• Description: An optional prefix for metric names

histogramBuckets

• Type: number[]
• Default: [5, 10, 25, 50, 100, 250, 500, 1000, 2500, 5000, 10000]

A non-empty list replaces the default boundaries for all three timing histograms. An empty list uses the defaults. Use finite, non-negative numbers in strictly increasing order. Values are in milliseconds.

export default defineNuxtConfig({
  prometheus: {
    histogramBuckets: [10, 50, 100, 250, 500, 1000],
  },
})

disableRequestInterceptor

• Type: boolean
• Default: false
• Description: Disables collection of outbound request timings.

When disabled, only total page timing metrics remain available. Request and render timing gauges and histograms are omitted because their values are unavailable. Default Node.js metrics, /metrics, and /health remain available.

When outbound collection is active, the module enables Nitro's experimental async context by default. This context keeps outbound request timings separate for concurrent server requests, including SSR. Background requests without a Nitro request context do not contribute to page timings.

An explicit nitro.experimental.asyncContext: false remains unchanged, but outbound request timings require this feature. See the Nitro async context documentation for runtime support and limitations.

metricsEndpoint

• Type: boolean
• Default: true
• Description: Whether to expose the /metrics endpoint. When set to false, metrics are still collected internally but the endpoint is not registered. This allows you to access metrics programmatically via the register object from @prometheus-io/client and expose them on a separate internal port.

Runtime Environment Variables

All options can be configured at runtime via environment variables following Nuxt's convention NUXT_PUBLIC_PROMETHEUS_<OPTION_NAME>:

Example usage:

# Disable metrics endpoint in production while keeping collection active
NUXT_PUBLIC_PROMETHEUS_METRICS_ENDPOINT=false node .output/server/index.mjs

# Use custom prefix
NUXT_PUBLIC_PROMETHEUS_PREFIX=myapp_ node .output/server/index.mjs

Development

The build uses TypeScript 5.9.3 because the current Nuxt module builder does not support the TypeScript 7 compiler API.

Outbound request timings are collected by src/runtime/collector. On Node.js the collector subscribes to the undici:request:*, http.client.* and http2.client.stream.* diagnostics channels. On Bun and Deno it wraps fetch, http, https and http2.connect, because those channels are missing or incomplete there. Neither adapter intercepts connections, so HTTP/2 and gRPC traffic works as before. Both are counted, because gRPC uses the Node.js HTTP/2 client.

# Install dependencies
pnpm install

# Prepare the module (build types and module)
pnpm run dev:prepare

# Start development server with playground
pnpm run dev

# Run tests
pnpm test

Important: After making changes to the module source code, you must run pnpm run dev:prepare to rebuild the module before testing.

Memory regression check

With k6 installed, run:

pnpm test:memory

The PR check uses a local fixture and fails if post-GC heap growth exceeds 8 MiB after warm-up. Logs, measurements, and a baseline heap snapshot are saved in reports/memory; failures also include a snapshot for comparison. CI uploads these files as the memory-regression artifact.

This short check cannot detect every slow leak. The collector lifecycle test separately checks that no state accumulates for requests that never settle.