Default Feature Flags Issue Links to Enabled

doc/operations/feature_flags.md

@@ -294,3 +294,35 @@ else
   puts "hello, world!"
 end
 ```
+
+## Feature Flag Related Issues
+
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/36617) in GitLab 13.2.
+> - It's deployed behind a feature flag, enabled by default.
+> - It's enabled on GitLab.com.
+> - It can't be enabled or disabled per-project
+> - It's recommended for production use.
+> - For GitLab self-managed instances, GitLab administrators can opt to disable it.
+
+You can link related issues to a feature flag. In the **Linked issues** section, click the `+` button and input the issue reference number or the full URL of the issue.
+
+This feature is similar to the [related issues](../user/project/issues/related_issues.md) feature.
+
+### Enable or disable Feature Flag Related Issues **(CORE ONLY)**
+
+Feature Flag Related Issues is under development but ready for production use.
+It is deployed behind a feature flag that is **enabled by default**.
+[GitLab administrators with access to the GitLab Rails console](../administration/feature_flags.md)
+can opt to disable it for your instance.
+
+To disable it:
+
+```ruby
+Feature.disable(:feature_flags_issue_links)
+```
+
+To enable it:
+
+```ruby
+Feature.enable(:feature_flags_issue_links)
+```

ee/app/controllers/projects/feature_flag_issues_controller.rb

@@ -30,7 +30,7 @@ module Projects
     end
 
     def ensure_feature_enabled!
-      render_404 unless Feature.enabled?(:feature_flags_issue_links, project)
+      render_404 unless Feature.enabled?(:feature_flags_issue_links, project, default_enabled: true)
     end
   end
 end

ee/app/views/projects/feature_flags/edit.html.haml

-- @gfm_form = Feature.enabled?(:feature_flags_issue_links, @project)
+- @gfm_form = Feature.enabled?(:feature_flags_issue_links, @project, default_enabled: true)
 
 - add_to_breadcrumbs s_('FeatureFlags|Feature Flags'), project_feature_flags_path(@project)
 - breadcrumb_title @feature_flag.name
@@ -8,4 +8,4 @@
                       project_id: @project.id,
                       feature_flags_path: project_feature_flags_path(@project),
                       environments_endpoint: search_project_environments_path(@project, format: :json),
-                      feature_flag_issues_endpoint: Feature.enabled?(:feature_flags_issue_links, @project) && can?(current_user, :read_issue_link, @project) ? project_feature_flag_issues_path(@project, @feature_flag) : ''} }
+                      feature_flag_issues_endpoint: Feature.enabled?(:feature_flags_issue_links, @project, default_enabled: true) && can?(current_user, :read_issue_link, @project) ? project_feature_flag_issues_path(@project, @feature_flag) : ''} }

ee/changelogs/unreleased/default-enable-feature-flag-issue-links.yml

+---
+title: Add related issues widget to feature flags
+merge_request: 36617
+author:
+type: added