Add new_jira_connect_ui feature flag

- Add feature flag on the backend and pass to frontend
- Hide some elements which will be removed in the new UI

app/controllers/jira_connect/subscriptions_controller.rb

@@ -19,6 +19,9 @@ class JiraConnect::SubscriptionsController < JiraConnect::ApplicationController
   before_action :allow_rendering_in_iframe, only: :index
   before_action :verify_qsh_claim!, only: :index
   before_action :authenticate_user!, only: :create
+  before_action do
+    push_frontend_feature_flag(:new_jira_connect_ui, type: :development)
+  end
 
   def index
     @subscriptions = current_jira_installation.subscriptions.preload_namespace_route

app/helpers/jira_connect_helper.rb

+# frozen_string_literal: true
+
+module JiraConnectHelper
+  def new_jira_connect_ui?
+    Feature.enabled?(:new_jira_connect_ui, type: :development)
+  end
+end

app/views/jira_connect/subscriptions/index.html.haml

@@ -23,15 +23,16 @@
   - else
     .js-jira-connect-app
 
-    %form#add-subscription-form.subscription-form{ action: jira_connect_subscriptions_path }
-      .ak-field-group
-        %label
-          GitLab namespace
+    - unless new_jira_connect_ui?
+      %form#add-subscription-form.subscription-form{ action: jira_connect_subscriptions_path }
+        .ak-field-group
+          %label
+            GitLab namespace
 
-      .ak-field-group.field-group-input
-        %input#namespace-input.ak-field-text{ type: 'text', required: true, placeholder: 'e.g. "MyCompany" or "MyCompany/GroupName"' }
-        %button.ak-button.ak-button__appearance-primary{ type: 'submit' }
-          Link namespace to Jira
+        .ak-field-group.field-group-input
+          %input#namespace-input.ak-field-text{ type: 'text', required: true, placeholder: 'e.g. "MyCompany" or "MyCompany/GroupName"' }
+          %button.ak-button.ak-button__appearance-primary{ type: 'submit' }
+            Link namespace to Jira
 
     - if @subscriptions.present?
       %table.subscriptions

app/views/layouts/jira_connect.html.haml

@@ -3,8 +3,9 @@
     %meta{ content: "text/html; charset=utf-8", "http-equiv" => "Content-Type" }
     %title
       GitLab
-    = stylesheet_link_tag 'https://unpkg.com/@atlaskit/css-reset@3.0.6/dist/bundle.css'
-    = stylesheet_link_tag 'https://unpkg.com/@atlaskit/reduced-ui-pack@10.5.5/dist/bundle.css'
+    - unless new_jira_connect_ui?
+      = stylesheet_link_tag 'https://unpkg.com/@atlaskit/css-reset@3.0.6/dist/bundle.css'
+      = stylesheet_link_tag 'https://unpkg.com/@atlaskit/reduced-ui-pack@10.5.5/dist/bundle.css'
     = yield :page_specific_styles
 
     = javascript_include_tag 'https://connect-cdn.atl-paas.net/all.js'

config/feature_flags/development/new_jira_connect_ui.yml

+---
+name: new_jira_connect_ui
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/49202
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/295647
+milestone: '13.7'
+type: development
+group: group::ecosystem
+default_enabled: false