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GitLab CI template for Lighthouse

This project implements a GitLab CI/CD template to continuously analyse your web apps and web pages performances and developer best practices with Lighthouse CI.

Usage

This template can be used both as a CI/CD component or using the legacy include:project syntax.

Use as a CI/CD component

Add the following to your gitlab-ci.yml:

include:
  # 1: include the component
  - component: gitlab.com/to-be-continuous/lighthouse/gitlab-ci-lighthouse@1.3.0
    # 2: set/override component inputs
    inputs:
      review-enabled: true # ⚠ this is only an example

Use as a CI/CD template (legacy)

Add the following to your gitlab-ci.yml:

include:
  # 1: include the template
  - project: 'to-be-continuous/lighthouse'
    ref: '1.3.0'
    file: '/templates/gitlab-ci-lighthouse.yml'

variables:
  # 2: set/override template variables
  REVIEW_ENABLED: "true" # ⚠ this is only an example

lighthouse job

This job runs the Lighthouse CI analysis.

It uses the following variable:

Input / Variable Description Default value
image / LHCI_IMAGE The Docker image used to run Lighthouse CI (use browser images only). registry.hub.docker.com/cypress/browsers:latest
version / LHCI_VERSION Lighthouse CI version to run latest
run-opts / LHCI_RUN_OPTS Lighthouse CI autorun options --upload.target=filesystem --collect.settings.chromeFlags=\"--no-sandbox\" --collect.url=\"%{environment_url}\"
review-enabled / REVIEW_ENABLED Set to true to enable Lighthouse tests on review environments (dynamic environments instantiated on development branches) none (disabled)

All the rest of your Lighthouse CI configuration shall be defined either as LHCI_ environment variables or in one of the supported configuration files, located at the root of your Git repository.

In addition to a textual report in the console, this job produces the following reports, kept for one day:

Report Format Usage
reports/lhci/*.{html|json} HTML report(s) n/a

$LHCI_RUN_OPTS late expansion

The $LHCI_RUN_OPTS variable supports a late variable expansion mechanism with the %{somevar} syntax.

Therefore if an upstream job in the pipeline deployed your code to a server and propagated the deployed server url as $environment_url variable (through a dotenv artifact), then you can easily run Lighthouse CI against this server, simply by using the %{environment_url} syntax in the $LHCI_RUN_OPTS variable.

⚠ all to be continuous depoyment templates implement this design. Therefore even purely dynamic environments (such as review environments) will automatically be propagated to your Lighthouse CI analysis.

If you're not using your own deployment job, you may:

  1. implement the common to be continuous design (i.e. propagate the environment base url as $environment_url variable through a dotenv artifact)
  2. use any programmatic solution of your choice with a JavaScript-based configuration file.
  3. explicitly set the collect.url option in the LHCI_RUN_OPTS variable (hardcoded to a single server),

Hook scripts

The Lighthouse template supports optional hook scripts from your project, located in the root directory to perform additional project-specific logic:

  • pre-lighthouse.sh is executed before running Lighthouse,
  • post-lighthouse.sh is executed after running Lighthouse (whichever the tests status).

Examples

Analysing multiple urls

This example demonstrates 2 techniques for a project willing to analyse several urls, also reusing the to be continuous $environment_url dynamic variable.

Solution 1: LHCI_RUN_OPTS-based

The easiest solution is to declare all the analysed urls in the $LHCI_RUN_OPTS variable using the late variable expansion mechanism.

include:
  - component: gitlab.com/to-be-continuous/lighthouse/gitlab-ci-lighthouse@1.3.0
    inputs:
      run-opts: >- 
    --upload.target=filesystem 
    --collect.settings.chromeFlags="--no-sandbox"
    --collect.url="%{environment_url}"
    --collect.url="%{environment_url}/admin" 
    --collect.url="%{environment_url}/profile"

Solution 2: Javascript-based

Another option could be to handle it in your JavaScript-based configuration file:

.gitlab-ci.yaml:

include:
  - component: gitlab.com/to-be-continuous/lighthouse/gitlab-ci-lighthouse@1.3.0
    inputs:
      run-opts: --upload.target=filesystem --collect.settings.chromeFlags=--no-sandbox

.lighthouserc.js:

// use $environment_url if set, else 'http://localhost:4200' (dev)
const baseUrl = process.env.environment_url || "http://localhost:4200";
module.exports = {
  ci: {
    collect: {
      startServerCommand: "npm run serve", // dev only, overridden by template in CI/CD
      url: [
        `${baseUrl}`,
        `${baseUrl}/admin`,
        `${baseUrl}/profile`
      ],
    },
    ...
  },
};