PMX

1.6.8 verified Sat May 09 auth: no javascript

PMX is the programmatic integration library for PM2 and Keymetrics.io (v1.6.8, latest stable). It enables Node.js applications to expose custom metrics (simple values, counters, meters, histograms), triggerable remote functions, exception alerts, custom events, and network traffic monitoring to the PM2 CLI and Keymetrics dashboard. Released irregularly with minor version bumps, it supports Node.js >= 0.10. Key differentiators: deep PM2/Keymetrics integration, low-overhead metric probes, and production monitoring without external monitoring services.

Common errors

error Cannot find module 'pmx' ↓

cause PMX not installed or not in node_modules.

fix

Run npm install pmx --save to add it to dependencies.

error pmx.probe is not a function ↓

cause Used named import instead of default import: `import { probe } from 'pmx'`.

fix

Use default import: import pmx from 'pmx' then pmx.probe().

error TypeError: pmx.metric is not a function ↓

cause Calling `pmx.metric()` directly instead of via probe.

fix

First create probe: const probe = pmx.probe() then use probe.metric().

Warnings

breaking pmx@1.0 removed the old 'pmx.init()' API; use 'pmx.init()' is now imported as default. ↓

fix Use default import `import pmx from 'pmx'` and call `pmx.init()` with options if needed.

gotcha The 'probe' object is obtained via `pmx.probe()` – it is not a direct export. ↓

fix Always call `const probe = pmx.probe()` before using metric, counter, meter, or histogram.

deprecated The 'event' method (pmx.event()) is deprecated; use custom events via Keymetrics API or pm2.io. ↓

fix Avoid using pmx.event(); instead emit custom events using pm2.connect or pm2.io packages.

gotcha Meter samples default to 1 (per second); to get per-minute rate set samples to 60. ↓

fix Set `samples: 60` in meter options if you need per-minute averaging.

gotcha Histogram measurement must be one of 'mean', 'median', 'p75', etc.; invalid values silently produce no data. ↓

fix Use only valid measurement strings: 'mean', 'median', 'p75', 'p95', 'p99', 'p999'.

Install

npm install pmx

yarn add pmx

pnpm add pmx

Imports

pmx
wrong
```
const pmx = require('pmx')
```
correct
```
import pmx from 'pmx'
```
Default ESM import; CJS require works in Node but may conflict with type module.

probe

wrong

const probe = require('pmx').probe()

correct

import pmx from 'pmx'; const probe = pmx.probe()

probe() is a method on the default export, not a named export.

Metric (type)
```
import type { Metric } from 'pmx'
```
TypeScript users should use `import type` for type-only imports; pmx ships its own types.

Quickstart

Initializes PMX, creates a metric tracking user count and a counter for HTTP requests.

import pmx from 'pmx';
import http from 'http';

const probe = pmx.probe();

const users = {};
const metric = probe.metric({
  name: 'Realtime user',
  value: () => Object.keys(users).length
});

const counter = probe.counter({ name: 'req/sec' });

http.createServer((req, res) => {
  counter.inc();
  res.end('ok');
}).listen(3000);

console.log('Server running on port 3000');