docs/data/reusables/actions/actions-vars-context-example-usage.md

If a configuration variable has not been set, the return value of an context referencing the variable will be an empty string.

The following examples shows using configuration variables with the vars context across a workflow. Each of the following configuration variables have been defined at the repository, organization, or environment levels.

{% raw %}

on:
  workflow_dispatch:
env:
  # Setting an environment variable with the value of a configuration variable
  env_var: ${{ vars.ENV_CONTEXT_VAR }}

jobs:
  display-variables:
    name: ${{ vars.JOB_NAME }}
    # You can use configuration variables with the `vars` context for dynamic jobs
    if: ${{ vars.USE_VARIABLES == 'true' }}
    runs-on: ${{ vars.RUNNER }}
    environment: ${{ vars.ENVIRONMENT_STAGE }}
    steps:
    - name: Use variables
      run: |
        echo "repository variable : ${{ vars.REPOSITORY_VAR }}"
        echo "organization variable : ${{ vars.ORGANIZATION_VAR }}"
        echo "overridden variable : ${{ vars.OVERRIDE_VAR }}"
        echo "variable from shell environment : $env_var"

    - name: ${{ vars.HELLO_WORLD_STEP }}
      if: ${{ vars.HELLO_WORLD_ENABLED == 'true' }}
      uses: actions/hello-world-javascript-action@main
      with:
        who-to-greet: ${{ vars.GREET_NAME }}

{% endraw %}