* Use environment variables (see [AUTOTITLE](/actions/reference/variables-reference#default-environment-variables)):

title: Contexts

shortTitle: Contexts

intro: 'Learn about contexts in {% data variables.product.prodname_actions %}.'

versions:

fpt: '*'

ghes: '*'

ghec: '*'

type: overview

topics:

- Actions

- Workflows

{% data reusables.actions.actions-contexts-about-description %} Each context is an object that contains properties, which can be strings or other objects.

{% data reusables.actions.context-contents %} For example, the `matrix` context is only populated for jobs in a [matrix](/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstrategymatrix).

You can access contexts using the expression syntax. For more information, see [AUTOTITLE](/actions/learn-github-actions/expressions).

{% raw %}

{% endraw %}

{% data reusables.actions.context-injection-warning %}

{% data variables.product.prodname_actions %} includes a collection of variables called _contexts_ and a similar collection of variables called _default variables_. These variables are intended for use at different points in the workflow:

* **Default environment variables:** These environment variables exist only on the runner that is executing your job. For more information, see [AUTOTITLE](/actions/learn-github-actions/variables#default-environment-variables).

* **Contexts:** You can use most contexts at any point in your workflow, including when _default 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 [AUTOTITLE](/actions/reference/accessing-contextual-information-about-workflow-runs#context-availability).

The following example demonstrates how these different types of variables can be used together in a job:

{% raw %}

```yaml copy

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"

- /variables

- /contexts

title: Variables

intro: 'Learn about variables in {% data variables.product.prodname_actions %} workflows.'

versions:

fpt: '*'

ghes: '*'

ghec: '*'

type: overview

topics:

- Action development

- Fundamentals

Variables provide a way to store and reuse non-sensitive configuration information. You can store any configuration data such as compiler flags, usernames, or server names as variables. Variables are interpolated on the runner machine that runs your workflow. Commands that run in actions or workflow steps can create, read, and modify variables.

You can set your own custom variables or use the default environment variables that {% data variables.product.prodname_dotcom %} sets automatically.

You can set a custom variable in two ways.

* To define an environment variable for use in a single workflow, you can use the `env` key in the workflow file. For more information, see [Defining environment variables for a single workflow](/actions/how-tos/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#defining-environment-variables-for-a-single-workflow).

* To define a configuration variable across multiple workflows, you can define it at the organization, repository, or environment level. For more information, see [Defining configuration variables for multiple workflows](/actions/how-tos/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#defining-configuration-variables-for-multiple-workflows).

For reference documentation, see [AUTOTITLE](/actions/reference/variables-reference).

* **Variables:** Scripts have access to the default variables. The full webhook event payload can be found in `GITHUB_EVENT_PATH`. For more information, see [AUTOTITLE](/actions/reference/variables-reference#default-environment-variables).

For more information, see [AUTOTITLE](/actions/reference/variables-reference#default-environment-variables) and [AUTOTITLE](/actions/security-guides/using-secrets-in-github-actions).

Travis CI and {% data variables.product.prodname_actions %} both include default environment variables that you can use in your YAML files. For {% data variables.product.prodname_actions %}, you can see these listed in [AUTOTITLE](/actions/reference/variables-reference#default-environment-variables).