GitHub Administrator GH-200 Book

GITHUB_WORKSPACE is a default environment variable in GitHub Actions that points to the directory on the runner where your repository is checked out. This variable allows you to access files within your repository during the workflow.

The action.yml file is the metadata file in a custom GitHub Action that defines the main entry point, including information such as the inputs, outputs, description, and the runs key that specifies the main entry point (e.g., a script or a Docker container).

To target a specific self-hosted runner, the job must use runs-on with labels that match that runner. A self-hosted runner normally has the self-hosted label plus default labels and any custom labels you assign. Since the runner is labeled runner1, the workflow should specify both self-hosted and runner1: runs-on: [self-hosted, runner1]. GitHub Actions will then route the job only to a self-hosted runner matching all specified labels. Option A targets a different custom label. Option B is malformed and also mixes a self-hosted label with a GitHub-hosted runner label. Option D targets any self-hosted runner, not specifically runner1. GitHub documents that an array of runs-on labels requires a runner matching all listed labels.

The correct GitHub Actions syntax for running a job across multiple Node.js versions is strategy.matrix. The matrix values are referenced at runtime through the matrix context, so node-version: ${{ matrix.node-ver }} is correct. Option A defines the matrix correctly but references it incorrectly through strategy.node-ver; matrix values are not accessed through the strategy context. Option C uses matrix-strategy, which is not a valid GitHub Actions workflow key. Option D reverses the structure by putting strategy under matrix, which is invalid. This question tests matrix strategy syntax, dynamic job configuration, and using matrix values as inputs to actions such as actions/setup-node. GitHub defines jobs. < job_id > .strategy.matrix as the proper matrix mechanism.