Document how to use status checks

doc/api/status_checks.md

@@ -195,3 +195,7 @@ Feature.disable(:ff_compliance_approval_gates)
 # For a single project
 Feature.disable(:ff_compliance_approval_gates, Project.find(<project id>)
 ```
+
+## Related links
+
+- [External status checks](../user/project/merge_requests/status_checks.md)

doc/user/project/merge_requests/status_checks.md

+---
+stage: Manage
+group: Compliance
+info: "To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments"
+type: reference, concepts
+disqus_identifier: 'https://docs.gitlab.com/ee/user/project/merge_requests/status_checks.html'
+---
+
+# External Status Checks **(ULTIMATE)**
+
+> - [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/3869) in GitLab 14.0.
+> - It's [deployed behind a feature flag](../../feature_flags.md), disabled by default.
+> - It's disabled on GitLab.com.
+> - It's not recommended for production use.
+> - To use it in GitLab self-managed instances, ask a GitLab administrator to [enable it](#enable-or-disable-status-checks). **(ULTIMATE SELF)**
+
+WARNING:
+This feature might not be available to you. Check the **version history** note above for details.
+
+You can create a status check that sends merge request data to third-party tools.
+When users create, change, or close merge requests, GitLab sends a notification. The users or automated workflows
+can then update the status of merge requests from outside of GitLab.
+
+With this integration, you can integrate with third-party workflow tools, like
+ServiceNow, or the custom tool of your choice. The third-party tool
+respond with an associated status. This status is then displayed as a non-blocking
+widget within the merge request to surface this status to the merge request author or reviewers
+at the merge request level itself.
+
+The lack of a status check response does not block the merging of a merge request.
+
+You can configure merge request status checks for each individual project. These are not shared between projects.
+
+To learn more about use cases, feature discovery, and development timelines,
+see the [external status checks epic](https://gitlab.com/groups/gitlab-org/-/epics/3869).
+
+## View the status checks on a project
+
+Within each project's settings, you can see a list of status checks added to the project:
+
+1. In your project, go to **Settings > General**.
+1. Expand the **Merge requests** section.
+1. Scroll down to the **Status checks** sub-section.
+
+![Status checks list](img/status_checks_list_view_v14_0.png)
+
+This list shows the service name, API URL, and targeted branch.
+It also provides actions to allow you to create, edit, or remove status checks.
+
+## Add or update a status check
+
+### Add a status check
+
+Within the **Status checks** sub-section, select the **Add status check** button.
+The **Add status check** form is then shown.
+
+![Status checks create form](img/status_checks_create_form_v14_0.png)
+
+Filling in the form and selecting the **Add status check** button creates a new status check.
+
+### Update a status check
+
+Within the **Status checks** sub-section, select the **Edit** button
+next to the status check you want to edit.
+The **Update status check** form is then shown.
+
+![Status checks update form](img/status_checks_update_form_v14_0.png)
+
+Changing the values in the form and selecting the **Update status check** button updates the status check.
+
+### Form values
+
+For common form errors see the [troubleshooting](#troubleshooting) section below.
+
+#### Service name
+
+This name can be any alphanumerical value and **must** be set. The name **must** be unique for
+the project.
+The name **has** to be unique for the project.
+
+#### API to check
+
+This field requires a URL and **must** use either the HTTP or HTTPs protocols.
+We **recommend** using HTTPs to protect your merge request data in transit.
+The URL **must** be set and **must** be unique for the project.
+
+#### Target branch
+
+If you want to restrict the status check to a single branch,
+you can use this field to set this limit.
+
+![Status checks branch selector](img/status_checks_branches_selector_v14_0.png)
+
+The branches list is populated from the projects [protected branches](../protected_branches.md).
+
+You can scroll through the list of branches or use the search box
+when there are a lot of branches and the branch you are looking
+for doesn't appear immediately. The search box requires
+**three** alphanumeric characters to be entered for the search to begin.
+
+If you want the status check to be applied to **all** merge requests,
+you can select the **Any branch** option.
+
+## Delete a status check
+
+Within the **Status checks** sub-section, select the **Remove...** button
+next to the status check you want to delete.
+The **Remove status check?** modal is then shown.
+
+![Status checks delete modal](img/status_checks_delete_modal_v14_0.png)
+
+To complete the deletion of the status check you must select the
+**Remove status check** button. This **permanently** deletes
+the status check and it **will not** be recoverable.
+
+## Troubleshooting
+
+### Duplicate value errors
+
+```plaintext
+Name is already taken
+---
+External API is already in use by another status check
+```
+
+On a per project basis, status checks can only use a name or API URL once.
+These errors mean that either the status checks name or API URL have already
+been used in this projects status checks.
+
+You must either choose a different
+value on the current status check or update the value on the existing status check.
+
+### Invalid URL error
+
+```plaintext
+Please provide a valid URL
+```
+
+The API to check field requires the URL provided to use either the HTTP or HTTPs protocols.
+You must update the value of the field to meet this requirement.
+
+### Branch list error during retrieval or search
+
+```plaintext
+Unable to fetch branches list, please close the form and try again
+```
+
+An unexpected response was received from the branches retrieval API.
+As suggested, you should close the form and reopen again or refresh the page. This error should be temporary, although
+if it persists please check the [GitLab status page](https://status.gitlab.com/) to see if there is a wider outage.
+
+## Enable or disable status checks **(ULTIMATE SELF)**
+
+Status checks are under development and not ready for production use. It is
+deployed behind a feature flag that is **disabled by default**.
+[GitLab administrators with access to the GitLab Rails console](../../../administration/feature_flags.md)
+can enable it.
+
+To enable it:
+
+```ruby
+# For the instance
+Feature.enable(:ff_compliance_approval_gates)
+# For a single project
+Feature.enable(:ff_compliance_approval_gates, Project.find(<project id>))
+```
+
+To disable it:
+
+```ruby
+# For the instance
+Feature.disable(:ff_compliance_approval_gates)
+# For a single project
+Feature.disable(:ff_compliance_approval_gates, Project.find(<project id>)
+```
+
+## Related links
+
+- [External status checks API](../../../api/status_checks.md)

doc/user/project/settings/index.md

@@ -249,6 +249,7 @@ Set up your project's merge request settings:
 - Set up the merge request method (merge commit, [fast-forward merge](../merge_requests/fast_forward_merge.md)).
 - Add merge request [description templates](../description_templates.md#description-templates).
 - Enable [merge request approvals](../merge_requests/approvals/index.md).
+- Enable [status checks](../merge_requests/status_checks.md).
 - Enable [merge only if pipeline succeeds](../merge_requests/merge_when_pipeline_succeeds.md).
 - Enable [merge only when all threads are resolved](../../discussions/index.md#only-allow-merge-requests-to-be-merged-if-all-threads-are-resolved).
 - Enable [require an associated issue from Jira](../../../integration/jira/issues.md#require-associated-jira-issue-for-merge-requests-to-be-merged).

ee/app/views/projects/_merge_request_status_checks_settings.html.haml

 .form-group
   %b= s_('StatusCheck|Status checks')
   %p.text-secondary
-    // Update the documentation link once https://gitlab.com/gitlab-org/gitlab/-/issues/329517 is complete
-    - link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: '' }
+    - link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: help_page_path('user/project/merge_requests/status_checks') }
     = s_('StatusCheck|Check for a status response in Merge Requests. Failures do not block merges. %{link_start}Learn more%{link_end}.').html_safe % { link_start: link_start, link_end: '</a>'.html_safe }
 
   #js-status-checks-settings{ status_checks_app_data(@project) }

ee/spec/views/projects/_merge_request_status_checks_settings.html.haml_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe 'projects/_merge_request_status_checks_settings' do
 
   it 'renders the settings description', :aggregate_failures do
     expect(rendered).to have_content 'Check for a status response in Merge Requests. Failures do not block merges.'
-    expect(rendered).to have_link 'Learn more', href: ''
+    expect(rendered).to have_link 'Learn more', href: '/help/user/project/merge_requests/status_checks'
   end
 
   it 'renders the settings app element', :aggregate_failures do