ci: use containers matrix name in github actions workflow

[MikeMcC399]

This PR changes the GitHub Actions matrix variable name from machines to containers in the workflow using-action.yml for consistency with the Cypress documentation (docs.cypress.io) and the Cypress GitHub Action repo (github.com/cypress-io/github-action). It also expands on the in-line explanation about the matrix array containers.

Reason for change

Although the workflow previously explained that the items in the matrix did not matter, it has led to some confusion in new users concerning the matrix variable name machines used by the example GitHub Action workflow using-action.yml:

    strategy:
      # when one test fails, DO NOT cancel the other
      # containers, because this will kill Cypress processes
      # leaving the Cypress Cloud dashboard hanging ...
      # https://github.com/cypress-io/github-action/issues/48
      fail-fast: false
      matrix:
        # run 4 copies of the current job in parallel
        # the actual items in the array do not matter
        # we just need to "force" GitHub CI to create 4 jobs
        machines: [1, 2, 3, 4]

The Cypress documentation (docs.cypress.io) and the Cypress GitHub Action repo (github.com/cypress-io/github-action) consistently use the variable

containers

as the name of the matrix array which defines how many parallel jobs are run when recording into Cypress Cloud.

The matrix variable name containers is simply a dummy name, which does not affect how the workflow runs, since the variable name is not used in any substitution. For comparison, in the job parallel-runs-across-platforms, the matrix variable name os and the array contents os: ['ubuntu-22.04', 'windows-latest', 'macos-latest'] are significant and these are used in substitution.

References

• GitHub documentation Using a matrix for your jobs
• Cypress Continuous Integration > GitHub Actions
• Cypress GitHub Action README > Parallel
• Cypress GitHub Action workflows
  • example-custom-ci-build-id.yml
  • example-recording.yml

[cypress-app-bot]

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[jennifer-shehane]

@MikeMcC399 Thanks for the improvement to user experience. The explanation and links to docs are really nice.

[cypress-app-bot]

🎉 This PR is included in version 2.0.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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