ES reindexing: add confirmation popup and change color scheme

ee/app/views/admin/application_settings/_elasticsearch_form.html.haml

@@ -102,7 +102,7 @@
 
         .sub-section
           %h4= _('Elasticsearch zero-downtime reindexing')
-          = link_to _('Trigger cluster reindexing'), admin_elasticsearch_trigger_reindexing_path, class: 'btn btn-success', method: :post, disabled: @elasticsearch_reindexing_task&.in_progress?
+          = link_to _('Trigger cluster reindexing'), admin_elasticsearch_trigger_reindexing_path, class: 'btn btn-primary', data: { confirm: _('Are you sure you want to reindex?') }, method: :post, disabled: @elasticsearch_reindexing_task&.in_progress?
           .form-text.text-muted
             = _('This feature should be used with an index that was created after 13.0')
           - Elastic::ReindexingTask.old_indices_scheduled_for_deletion.each do |task|
@@ -124,7 +124,7 @@
               - percentage = ((processed_documents / expected_documents.to_f) * 100).round(2)
               %p= _('Documents reindexed: %{processed_documents} (%{percentage}%%)') % { processed_documents: processed_documents, percentage: percentage }
               .progress
-                .progress-bar.progress-bar-striped.bg-success{ "aria-valuemax" => "100", "aria-valuemin" => "0", "aria-valuenow" => percentage, :role => "progressbar", :style => "width: #{percentage}%" }
+                .progress-bar.progress-bar-striped.bg-primary{ "aria-valuemax" => "100", "aria-valuemin" => "0", "aria-valuenow" => percentage, :role => "progressbar", :style => "width: #{percentage}%" }
 
         .sub-section
           %h4= _('Elasticsearch indexing restrictions')

ee/changelogs/unreleased/change-es-reindexing-color-scheme.yml

+---
+title: 'Elasticsearch reindexing: add confirmation popup and change color scheme'
+merge_request: 42209
+author:
+type: other

ee/spec/features/admin/admin_settings_spec.rb

@@ -162,6 +162,17 @@ RSpec.describe 'Admin updates EE-only settings' do
       expect(ElasticsearchIndexedProject.count).to eq(0)
       expect(page).to have_content 'Application settings saved successfully'
     end
+
+    it 'zero-downtime reindexing shows popup', :js do
+      page.within('.as-elasticsearch') do
+        expect(page).to have_content 'Trigger cluster reindexing'
+        click_link 'Trigger cluster reindexing'
+      end
+
+      text = page.driver.browser.switch_to.alert.text
+      expect(text).to eq 'Are you sure you want to reindex?'
+      page.driver.browser.switch_to.alert.accept
+    end
   end
 
   it 'Enable Slack application' do

locale/gitlab.pot

@@ -3358,6 +3358,9 @@ msgstr ""
 msgid "Are you sure you want to regenerate the public key? You will have to update the public key on the remote server before mirroring will work again."
 msgstr ""
 
+msgid "Are you sure you want to reindex?"
+msgstr ""
+
 msgid "Are you sure you want to remove %{group_name}?"
 msgstr ""