Add new runner variable runner.arch (#12374)

Co-authored-by: Lucas Costi <lucascosti@users.noreply.github.com>

Author: fhammerl

content/actions/learn-github-actions/contexts.md

@@ -139,7 +139,8 @@ The `runner` context contains information about the runner that is executing the
 | Property name | Type | Description |
 |---------------|------|-------------|
 | `runner.name` | `string` | {% data reusables.actions.runner-name-description %} |
-| `runner.os` | `string` | {% data reusables.actions.runner-os-description %} |
+| `runner.os` | `string` | {% data reusables.actions.runner-os-description %} |{% if actions-runner-arch-envvars %}
+| `runner.arch` | `string` | {% data reusables.actions.runner-arch-description %} |{% endif %}
 | `runner.temp` | `string` | {% data reusables.actions.runner-temp-directory-description %} |
 | `runner.tool_cache` | `string` | {% ifversion ghae %}For instructions on how to make sure your {% data variables.actions.hosted_runner %} has the required software installed, see "[Creating custom images](/actions/using-github-hosted-runners/creating-custom-images)." {% else %} {% data reusables.actions.runner-tool-cache-description %} {% endif %}|
 

content/actions/learn-github-actions/environment-variables.md

@@ -79,7 +79,8 @@ We strongly recommend that actions use environment variables to access the files
 | `GITHUB_API_URL` | Returns the API URL. For example: `{% data variables.product.api_url_code %}`.
 | `GITHUB_GRAPHQL_URL` | Returns the GraphQL API URL. For example: `{% data variables.product.graphql_url_code %}`.
 | `RUNNER_NAME` | {% data reusables.actions.runner-name-description %}
-| `RUNNER_OS` | {% data reusables.actions.runner-os-description %}
+| `RUNNER_OS` | {% data reusables.actions.runner-os-description %}{% if actions-runner-arch-envvars %}
+| `RUNNER_ARCH` | {% data reusables.actions.runner-arch-description %}{% endif %}
 | `RUNNER_TEMP` | {% data reusables.actions.runner-temp-directory-description %}
 {% ifversion not ghae %}| `RUNNER_TOOL_CACHE` | {% data reusables.actions.runner-tool-cache-description %}{% endif %}
 

data/features/actions-runner-arch-envvars.yml

@@ -0,0 +1,7 @@
+# Reference: #5727
+# Documentation for new runner 'arch' environment variables set by the `runner` app.
+versions:
+  fpt: '*'
+  ghec: '*'
+  ghes: '>=3.4'
+  ghae: 'ghae-issue-5727'

data/reusables/actions/runner-arch-description.md

@@ -0,0 +1 @@
+The architecture of the runner executing the job. Possible values are `X86`, `X64`, `ARM`, and `ARM64`.