playwright-prometheus-remote-write-reporter v0.0.4

playwright-prometheus-remote-write-reporter

Get Started

NOTE: We need to configure prometheus as a precondition.

1. Enable feature flag - remote write receiver
2. in prometheus.yml file add next configuration:

...
remote_write:
    # local?
  - url: http://localhost:9090/api/v1/write
...

You may found complete example in example folder.

Installation

npm i playwright-prometheus-remote-write-reporter # npm
yarn add playwright-prometheus-remote-write-reporter # yarn
pnpm add playwright-prometheus-remote-write-reporter # pnpm
bun a playwright-prometheus-remote-write-reporter # bun

Configure reporter

In your playwright.config.ts add next lines:

export default defineConfig({
// ...
  reporter: [
    ['playwright-prometheus-remote-write-reporter', {
      // options object
    }]
  ],
// ...
})

Reporter Options

Collected metrics

Each metric name starts from prefix. By default it's pw_. So every metric name described without prefix.

Test(s)

this metrics below sends periodically and you may found when they sends

Node.js internals

This metrics collects every reporter lifecycle.

Playwright Reporter API hooks

1: Do not use "process.env.name" variable since it can overwrite your "node_env" metric.

2: docs: https://nodejs.org/docs/latest/api/process.html#processenv

3: docs: https://nodejs.org/docs/latest/api/process.html#processargv

4: docs: https://nodejs.org/docs/latest/api/process.html#processversions

5: docs: https://nodejs.org/docs/latest/api/os.html#osarch

6: docs: https://nodejs.org/docs/latest/api/process.html#processcpuusagepreviousvalue

7: docs: https://nodejs.org/docs/latest/api/process.html#processmemoryusage

Using custom metrics

You can define own metrics following next code:

import { test } from '@playwright/test'
import { Counter, Gauge } from 'playwright-prometheus-remote-write-reporter'

const countOfUrlCalls = new Counter({
  // only name is requrired
  name: 'url_open' // will automatically appends prefix
}, 0) // starts from 0

test('simple counter test', async ({ page }) => {
  await page.goto('https://example.com')
  countOfUrlCalls.inc()

  // ... rest test
})

test.afterAll(() => {
  countOfUrlCalls.collect() // sends metrics to prometheus
})

Counter

Counters go up, and reset when the process restarts.

Counter API

• constructor(labels, initialValue)
  • labels: Record<string, string> - collected metrics. only name field is required.
  • initialValue: number - default is 0. If metric is constant we recommend to set to 1
• inc([value]) increments your counter.
  • value: number | undefined - count of increasing
• collect() - Send metrics to prometheus
• labels(label) - append extra labels
  • label: Record<string, string>. Do not overwrite name property.

Gauge

Gauges are similar to Counters but a Gauge's value can be decreased.

Gauge API

Same for Counter

• set(value) - set gauge value
  • value: number
• zero() - same as set(0)
• dec([value]) - decrement gauge value
  • value: number | undefined

Best practice

We Highly recommend use one of 2 practiceies for send metrics to prometheus via collect method:

• on afterEach/afterAll hook
• on base hook

example:

import { test as base } from '@playwright/test'
import { Counter, Gauge } from 'playwright-prometheus-remote-write-reporter'

type Context = {
  urlCalls: Counter
}

const test = base.extend<Context>({
  urlCalls: async ({}, use) => {
    const counter = new Counter({name: 'url_calls'})
    await use(counter)
    // automatically sends metrics
    counter.collect()
  }
})

test('extended test', ({urlCalls}) => {
  // ...
  urlCalls.inc()
})

// or
const anotherCounter = new Counter({name: 'custom_counter'})
base('some test', () => {
  anotherCounter.inc()
})
base.afterAll(() => {
  anotherCounter.colect()
})