uw-lib-prometheus.js

A wrapper around prom-client.

Install

npm install --save uw-lib-prometheus.js

Use

const prometheus = require('uw-lib-prometheus.js')();

prometheus.newGauge('name', 'help').set(10);

Quick express example is available in examples directory.

API

Prometheus.constructor(string prefix) if prefix provided, it will prefix ;) each metric name.

The new* methods are just decorators for prom-client metric objects and are responsible for some dupe vaidation and making sure metric objects are added into registry.

Prometheus.newGauge(string name, string help, string[] labels) creates new Gauge.

Prometheus.newHistogram(string name, string help, string[] labels, {buckets: []}) creates new Histogram.

Prometheus.metric(string name) returns previously created metric by name.

Middleware

Prometheus.middleware() returns a factory for middleware handlers. Following handlers are available:

report() - dumps plain text metrics for Prometheus server to scrape.

requestDuration(string|Histogram histogram) - records request duration in seconds, will try and assign labels based on what the histogram has defined, recognised labels are

• http_status - captures status on the response object
• http_method - captures request method (POST, GET etc.)
• path - captures request path, note that for parametrised routes it will capture actual parameters (eg. /user/123123)
• route - captures route regex, this is useful for parametrised routes (eg. /user/:id)

heapUsage(string|Gauge used, string|Gauge total) - records used and total heap in bytes.

NPM

Lib is published on NPM under the utilitywarehosue namespace. It is public.

yarn add @utilitywarehouse/uw-lib-prometheus.js