Documentation on these metrics in the works. If you hit bugs in the metrics collection, report at Lighthouse issues. How to use article

Install

$ yarn global add pwmetrics
# or
$ yarn add --dev pwmetrics

CLI Usage

$ pwmetrics <url> <flags>

pwmetrics http://example.com/

# --runs=n     Does n runs (eg. 3, 5), and reports the median run's numbers.
#              Median run selected by run with the median TTI.
pwmetrics http://example.com/ --runs=3

# --json       Reports json details to stdout.
pwmetrics http://example.com/ --json

# returns...
# {runs: [{
#   "timings": [
#     {
#       "name": "First Contentful Paint",
#       "value": 289.642
#     },
#     {
#       "name": "First Meaningful Paint",
#       "value": 289.6
#     },
#     ...

# --output-path       File path to save results.
pwmetrics http://example.com/ --output-path='pathToFile/file.json'

# --config        Provide configuration (defaults to `package.json`). See _Defining config_ below.
pwmetrics --config=pwmetrics-config.js

# --submit       Submit results to Google Sheets. See _Defining submit_ below.
pwmetrics --submit

# --upload       Upload Lighthouse traces to Google Drive. See _Defining upload_ below.
pwmetrics --upload

# --view       View Lighthouse traces, which were uploaded to Google Drive, in DevTools. See _Defining view_ below.
pwmetrics --view

##
## CLI options useful for CI
##

# --expectations  Assert metrics results against provides values. See _Defining expectations_ below.
pwmetrics --expectations

# --fail-on-error  Exit PWMetrics with an error status code after the first unfilled expectation.
pwmetrics --fail-on-error

Defining config

# run pwmetrics with config in package.json
pwmetrics --config

package.json

...
  "pwmetrics": {
    "url": "http://example.com/",
    // other configuration options
  }
...

# run pwmetrics with config in pwmetrics-config.js
pwmetrics --config=pwmetrics-config.js

pwmetrics-config.js

module.exports = {
  url: 'http://example.com/',
   // other configuration options. Read _All available configuration options_
}

All available configuration options

pwmetrics-config.js

const METRICS = require('pwmetrics/lib/metrics');

module.exports = {
  url: 'http://example.com/',
  flags: { // AKA feature flags
    runs: 3, // number or runs
    submit: true, // turn on submitting to Google Sheets
    upload: true, // turn on uploading to Google Drive
    view: true, // open uploaded traces to Google Drive in DevTools
    expectations: true, // turn on assertion metrics results against provides values
    json: true, // not required, set to true if you want json output
    outputPath: 'stdout', // not required, only needed if you have specified json output, can be "stdout" or a path
    chromePath: '/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary', //optional path to specific Chrome location
    chromeFlags: '', // custom flags to pass to Chrome. For a full list of flags, see http://peter.sh/experiments/chromium-command-line-switches/.
    // Note: pwmetrics supports all flags from Lighthouse
    showOutput: true, // not required, set to false for pwmetrics not output any console.log messages
    failOnError: false // not required, set to true if you want to fail the process on expectations errors
  },
  expectations: {
    // these expectations values are examples, for your cases set your own
    // it's not required to use all metrics, you can use just a few of them
    // Read _Available metrics_ where all keys are defined
    [METRICS.TTFCP]: {
      warn: '>=1500',
      error: '>=2000'
    },
    [METRICS.TTFMP]: {
      warn: '>=2000',
      error: '>=3000'
    },
    [METRICS.TTI]: {
      ...
    },
    [METRICS.TTFCPUIDLE]: {
      ...
    },
    [METRICS.SI]: {
      ...
    },
  },
  sheets: {
    type: 'GOOGLE_SHEETS', // sheets service type. Available types: GOOGLE_SHEETS
    options: {
      spreadsheetId: 'sheet_id',
      tableName: 'data',
      uploadMedian: false // not required, set to true if you want to upload only the median run
    }
  },
  clientSecret: {
    // Data object. Can be get
    // either
    // by (using everything in step 1 here)[https://developers.google.com/sheets/api/quickstart/nodejs#step_1_turn_on_the_api_name]
    //
    // example format:
    //
    // installed: {
    //   client_id: "sample_client_id",
    //   project_id: "sample_project_id",
    //   auth_uri: "https://accounts.google.com/o/oauth2/auth",
    //   token_uri: "https://accounts.google.com/o/oauth2/token",
    //   auth_provider_x509_cert_url: "https://www.googleapis.com/oauth2/v1/certs",
    //   client_secret: "sample_client_secret",
    //   redirect_uris: [
    //     "url",
    //     "http://localhost"
    //   ]
    // }
    //
    // or
    // by (using everything in step 1 here)[https://developers.google.com/drive/v3/web/quickstart/nodejs]
  }
}

Defining expectations

Recipes for using with CI

# run pwmetrics with config in package.json
pwmetrics --expectations

package.json

...
  "pwmetrics": {
    "url": "http://example.com/",
    "expectations": {
      ...
    }
  }
...

# run pwmetrics with config in pwmetrics-config.js
pwmetrics --expectations --config=pwmetrics-config.js

Defining submit

Submit results to Google Sheets

Instructions:

• Copy this spreadsheet.
• Copy the ID of the spreadsheet into the config as value of sheets.options.spreadsheetId property.
• Setup Google Developer project and get credentials. (everything in step 1 here)
• Take a client_secret and put it into the config as value of clientSecret property.

# run pwmetrics with config in package.json
pwmetrics --submit

# run pwmetrics with config in pwmetrics-config.js
pwmetrics --submit --config=pwmetrics-config.js

pwmetrics-config.js

module.exports = {
  'url': 'http://example.com/',
  'sheets': {
    ...
  },
  'clientSecret': {
    ...
  }
}

Defining upload

Upload Lighthouse traces to Google Drive

Instructions:

• Setup Google Developer project and get credentials. (everything in step 1 here)
• Take a client_secret and put it into the config as value of clientSecret property.

# run pwmetrics with config in package.json
pwmetrics --upload

# run pwmetrics with config in pwmetrics-config.js
pwmetrics --upload --config=pwmetrics-config.js

pwmetrics-config.js

module.exports = {
  'url': 'http://example.com/',
  'clientSecret': {
    ...
  }
}

View Lighthouse traces in timeline-viewer

Show Lighthouse traces in timeline-viewer.

Required to use upload flag

timeline-viewer - Shareable URLs for your Chrome DevTools Timeline traces.

# run pwmetrics with config in package.json
pwmetrics --upload --view

# run pwmetrics with config in your-own-file.js
pwmetrics --upload --view --config=your-own-file.js

pwmetrics-config.js

module.exports = {
  'url': 'http://example.com/',
  'clientSecret': {
    ...
  }
}

Available metrics:

All metrics now are stored in separate constant object located in pwmetrics/lib/metrics/metrics;

// lib/metrics/metrics.ts
{
  METRICS: {
    TTFCP: 'firstContentfulPaint',
    TTFMP: 'firstMeaningfulPaint',
    TTFCPUIDLE: 'firstCPUIdle',
    TTI: 'interactive',
    SI: 'speedIndex'
  }
}

Read article Performance metrics. What’s this all about? which is decoding this metrics.

API

const PWMetrics = require('pwmetrics');

const options = {
  flags: {
    runs: 3, // number or runs
    submit: true, // turn on submitting to Google Sheets
    upload: true, // turn on uploading to Google Drive
    view: true, // open uploaded traces to Google Drive in DevTools
    expectations: true, // turn on assertation metrics results against provides values
    chromeFlags: '--headless' // run in headless Chrome
  }
};

const pwMetrics = new PWMetrics('http://example.com/', options); // _All available configuration options_ can be used as `options`
pwMetrics.start(); // returns Promise

Options

*pwmetrics supports all flags from Lighthouse. See here for the complete list.

Recipes

• gulp

License

Apache 2.0. Google Inc.