d3db7d3e25
* Detail where each context can be used within a workflow * tweak * Update cross-ref to new information This reusable is used in two articles: 'Context and expression syntax for GitHub Actions' and 'Environment variables'. In the first of these the current link point to the same section that the link is added to (which is not useful). In both articles I think the new section about context availability is a more appropriate link. * Update content/actions/reference/context-and-expression-syntax-for-github-actions.md Co-authored-by: hubwriter <hubwriter@github.com> * Update content/actions/reference/context-and-expression-syntax-for-github-actions.md Co-authored-by: hubwriter <hubwriter@github.com> * Update content/actions/reference/context-and-expression-syntax-for-github-actions.md Co-authored-by: hubwriter <hubwriter@github.com> Co-authored-by: Matt Pollard <mattpollard@users.noreply.github.com> Co-authored-by: hubwriter <hubwriter@github.com>
22 lines
2.1 KiB
Markdown
22 lines
2.1 KiB
Markdown
{% data variables.product.prodname_actions %} includes a collection of variables called _contexts_ and a similar collection of variables called _default environment variables_. These variables are intended for use at different points in the workflow:
|
|
|
|
- **Default environment variables:** These variables exist only on the runner that is executing your job. For more information, see "[Default environment variables](/actions/reference/environment-variables#default-environment-variables)."
|
|
- **Contexts:** You can use most contexts at any point in your workflow, including when _default environment variables_ would be unavailable. For example, you can use contexts with expressions to perform initial processing before the job is routed to a runner for execution; this allows you to use a context with the conditional `if` keyword to determine whether a step should run. Once the job is running, you can also retrieve context variables from the runner that is executing the job, such as `runner.os`. For details of where you can use various contexts within a workflow, see "[Context availability](/actions/reference/context-and-expression-syntax-for-github-actions#context-availability)."
|
|
|
|
The following example demonstrates how these different types of environment variables can be used together in a job:
|
|
|
|
{% raw %}
|
|
```yaml
|
|
name: CI
|
|
on: push
|
|
jobs:
|
|
prod-check:
|
|
if: ${{ github.ref == 'refs/heads/main' }}
|
|
runs-on: ubuntu-latest
|
|
steps:
|
|
- run: echo "Deploying to production server on branch $GITHUB_REF"
|
|
```
|
|
{% endraw %}
|
|
|
|
In this example, the `if` statement checks the [`github.ref`](/actions/reference/context-and-expression-syntax-for-github-actions#github-context) context to determine the current branch name; if the name is `refs/heads/main`, then the subsequent steps are executed. The `if` check is processed by {% data variables.product.prodname_actions %}, and the job is only sent to the runner if the result is `true`. Once the job is sent to the runner, the step is executed and refers to the [`$GITHUB_REF`](/actions/reference/environment-variables#default-environment-variables) environment variable from the runner.
|