Revert "Revert "[April 13] serialization feature doc"" (github#18742)

content/actions/reference/environments.md

@@ -71,6 +71,9 @@ For more information on syntax to reference environments in workflows, see "[Wor
 
 When a workflow references an environment, the environment will appear in the repository's deployments. For more information about viewing current and previous deployments, see "[Viewing deployment history](/developers/overview/viewing-deployment-history)."
 
+### Using concurrency to serialize deployments in an environment
+You can use concurrency so that an environment has a maximum of one deployment in progress and one deployment pending at a time. For more information, see "[Workflow syntax for GitHub Actions](/actions/reference/workflow-syntax-for-github-actions#concurrency)."
+
 ### Deleting an environment
 
 {% data reusables.github-actions.permissions-statement-environment %}

content/actions/reference/workflow-syntax-for-github-actions.md

@@ -221,6 +221,18 @@ defaults:
     working-directory: scripts
 ```
 
+{% if currentVersion == "free-pro-team@latest" or currentVersion ver_gt "enterprise-server@3.0" or currentVersion == "github-ae@next" %}
+### `concurrency`
+
+{% data reusables.actions.concurrency-beta %}
+
+Concurrency ensures that only a single job or workflow using the same concurrency group will run at a time. A concurrency group can be any string or expression. The expression can only use the `github` context. For more information about expressions, see "[Context and expression syntax for {% data variables.product.prodname_actions %}](/actions/reference/context-and-expression-syntax-for-github-actions)."
+
+You can also specify `concurrency` at the job level. For more information, see [`jobs.<job_id>.concurrency`](/actions/automating-your-workflow-with-github-actions/workflow-syntax-for-github-actions#jobsjob_idconcurrency).
+
+{% data reusables.actions.actions-group-concurrency %}
+
+{% endif %}
 ### `jobs`
 
 A workflow run is made up of one or more jobs. Jobs run in parallel by default. To run jobs sequentially, you can define dependencies on other jobs using the `jobs.<job_id>.needs` keyword.
@@ -347,10 +359,11 @@ The environment that the job references. All environment protection rules must p
 You can provide the environment as only the environment `name`, or as an environment object with the `name` and `url`. The URL maps to `environment_url` in the deployments API. For more information about the deployments API, see "[Deployments](/rest/reference/repos#deployments)."
 
 ##### Example using a single environment name
-
+{% raw %}
 ```yaml
 environment: staging_environment
 ```
+{% endraw %}
 
 ##### Example using environment name and URL
 
@@ -372,6 +385,25 @@ environment:
 {% endraw %}
 {% endif %}
 
+
+{% if currentVersion == "free-pro-team@latest" or currentVersion ver_gt "enterprise-server@3.0" or currentVersion == "github-ae@next" %}
+### `jobs.<job_id>.concurrency`
+
+{% data reusables.actions.concurrency-beta %}
+
+{% note %}
+
+**Note:** When concurrency is specified at the job level, order is not guaranteed for jobs or runs that queue within 5 minutes of each other.
+
+{% endnote %}
+
+Concurrency ensures that only a single job or workflow using the same concurrency group will run at a time. A concurrency group can be any string or expression. The expression can use any context except for the `secrets` context. For more information about expressions, see "[Context and expression syntax for {% data variables.product.prodname_actions %}](/actions/reference/context-and-expression-syntax-for-github-actions)."
+
+You can also specify `concurrency` at the workflow level. For more information, see [`concurrency`](/actions/automating-your-workflow-with-github-actions/workflow-syntax-for-github-actions#concurrency).
+
+{% data reusables.actions.actions-group-concurrency %}
+
+{% endif %}
 ### `jobs.<job_id>.outputs`
 
 A `map` of outputs for a job. Job outputs are available to all downstream jobs that depend on this job. For more information on defining job dependencies, see [`jobs.<job_id>.needs`](#jobsjob_idneeds).

data/reusables/actions/actions-group-concurrency.md

@@ -0,0 +1,25 @@
+When a concurrent job or workflow is queued, if another job or workflow using the same concurrency group in the repository is in progress, the queued job or workflow will be `pending`. Any previously pending job or workflow in the concurrency group will be canceled. To also cancel any currently running job or workflow in the same concurrency group, specify `cancel-in-progress: true`.
+
+##### Examples using concurrency and the default behavior
+
+{% raw %}
+```yaml
+concurrency: staging_environment
+```
+{% endraw %}
+
+{% raw %}
+```yaml
+concurrency: ci-${{ github.ref }}
+```
+{% endraw %}
+
+##### Example using concurrency to cancel any in-progress job or run
+
+{% raw %}
+```yaml
+concurrency: 
+  group: ${{ github.head_ref }}
+  cancel-in-progress: true
+```
+{% endraw %}

data/reusables/actions/concurrency-beta.md

@@ -0,0 +1,5 @@
+{% note %}
+
+**Note:** Concurrency is currently in beta and subject to change.
+
+{% endnote %}