Prohibit automatic elasticsearch indexes creation

This change disables "Index all project" button if ES
cluster doesn't have index created and shows a warning on
the ES integration page

changelogs/unreleased/13717-es-indexing-without-index.yml

+---
+title: 'Elasticsearch: when index is absent warn users and disable index button'
+merge_request: 25254
+author:
+type: fixed

ee/app/controllers/admin/elasticsearch_controller.rb

@@ -4,7 +4,7 @@ class Admin::ElasticsearchController < Admin::ApplicationController
   before_action :check_elasticsearch_web_indexing_feature_flag!
 
   def check_elasticsearch_web_indexing_feature_flag!
-    render_404 unless Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true)
+    render_404 unless Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true) && Gitlab::Elastic::Helper.index_exists?
   end
 
   # POST

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

@@ -22,14 +22,19 @@
         .sub-section
           .form-group
             .form-check
-              = f.check_box :elasticsearch_indexing, class: 'form-check-input', data: { qa_selector: 'indexing_checkbox' }
+              - indexing_enabled = Gitlab::CurrentSettings.elasticsearch_indexing?
+              - index_exists = Gitlab::Elastic::Helper.index_exists? rescue false
+              - disable_indexing_checkbox = !indexing_enabled && !index_exists # Disable this checkbox only when we haven't enabled indexing and we don't have an index
+              = f.check_box :elasticsearch_indexing, class: 'form-check-input', data: { qa_selector: 'indexing_checkbox' }, disabled: disable_indexing_checkbox
               = f.label :elasticsearch_indexing, class: 'form-check-label' do
                 Elasticsearch indexing
-
-              - if Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true) && Gitlab::CurrentSettings.elasticsearch_indexing?
+              - unless index_exists
+                .form-text.text-warning
+                  = _('Please create an index before enabling indexing')
+              - if Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true) && indexing_enabled
                 .form-text
                   = link_to _('Index all projects'), admin_elasticsearch_enqueue_index_path,
-                      class: 'btn btn-success', method: :post
+                      class: ['btn', 'btn-success', ('disabled' unless index_exists)], method: :post
 
           .form-group
             .form-check

ee/lib/gitlab/elastic/helper.rb

@@ -56,6 +56,14 @@ module Gitlab
         Project.__elasticsearch__.version(version).delete_index!
       end
 
+      def self.index_exists?(version = ::Elastic::MultiVersionUtil::TARGET_VERSION)
+        proxy = Project.__elasticsearch__.version(version)
+        client = proxy.client
+        index_name = proxy.index_name
+
+        client.indices.exists? index: index_name # rubocop:disable CodeReuse/ActiveRecord
+      end
+
       # Calls Elasticsearch refresh API to ensure data is searchable
       # immediately.
       # https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-refresh.html

ee/spec/controllers/admin/elasticsearch_controller_spec.rb

@@ -11,6 +11,7 @@ describe Admin::ElasticsearchController do
     end
 
     it 'starts indexing' do
+      expect(Gitlab::Elastic::Helper).to(receive(:index_exists?)).and_return(true)
       expect_next_instance_of(::Elastic::IndexProjectsService) do |service|
         expect(service).to receive(:execute)
       end
@@ -21,6 +22,20 @@ describe Admin::ElasticsearchController do
       expect(response).to redirect_to integrations_admin_application_settings_path(anchor: 'js-elasticsearch-settings')
     end
 
+    context 'without an index' do
+      before do
+        allow(Gitlab::Elastic::Helper).to(receive(:index_exists?)).and_return(false)
+      end
+
+      it 'does nothing and returns 404' do
+        expect(::Elastic::IndexProjectsService).not_to receive(:new)
+
+        post :enqueue_index
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
     context 'when feature is disabled' do
       it 'does nothing and returns 404' do
         stub_feature_flags(elasticsearch_web_indexing: false)

ee/spec/features/admin/admin_settings_spec.rb

@@ -9,6 +9,7 @@ describe 'Admin updates EE-only settings' do
     stub_env('IN_MEMORY_APPLICATION_SETTINGS', 'false')
     sign_in(create(:admin))
     allow(License).to receive(:feature_available?).and_return(true)
+    allow(Gitlab::Elastic::Helper).to receive(:index_exists?).and_return(true)
   end
 
   context 'Geo settings' do

ee/spec/lib/ee/gitlab/elastic/helper_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+describe Gitlab::Elastic::Helper do
+  describe '.index_exists' do
+    it 'returns correct values' do
+      described_class.create_empty_index
+
+      expect(described_class.index_exists?).to eq(true)
+
+      described_class.delete_index
+
+      expect(described_class.index_exists?).to eq(false)
+    end
+  end
+end

ee/spec/views/admin/application_settings/_elasticsearch_form.html.haml_spec.rb

@@ -12,6 +12,57 @@ describe 'admin/application_settings/_elasticsearch_form' do
     allow(view).to receive(:expanded) { true }
   end
 
+  context 'es index dependent' do
+    before do
+      allow(Gitlab::CurrentSettings).to(receive(:elasticsearch_indexing?)).and_return(es_indexing)
+      allow(Gitlab::Elastic::Helper).to(receive(:index_exists?)).and_return(index_exists)
+    end
+
+    let(:warning_msg) { 'create an index before enabling indexing' }
+    let(:button_text) { 'Index all projects' }
+    let(:application_setting) { build(:application_setting, elasticsearch_indexing: es_indexing) }
+
+    context 'when elasticsearch index does not exist with indexing enabled' do
+      let(:es_indexing) { true }
+      let(:index_exists) { false }
+
+      it 'shows a warning and disables a button' do
+        render
+
+        expect(rendered).to have_content(warning_msg)
+        expect(rendered).to have_css('a.btn-success.disabled', text: button_text)
+        expect(rendered).to have_css('#application_setting_elasticsearch_indexing')
+        expect(rendered).not_to have_css('#application_setting_elasticsearch_indexing[disabled="disabled"]')
+      end
+    end
+
+    context 'when elasticsearch index does not exist with indexing disabled' do
+      let(:es_indexing) { false }
+      let(:index_exists) { false }
+
+      it 'shows a warning and disables a checkbox and hides an indexing button' do
+        render
+
+        expect(rendered).to have_content(warning_msg)
+        expect(rendered).not_to have_css('a.btn-success', text: button_text)
+        expect(rendered).to have_css('#application_setting_elasticsearch_indexing[disabled="disabled"]')
+      end
+    end
+
+    context 'when elasticsearch index exists' do
+      let(:es_indexing) { true }
+      let(:index_exists) { true }
+
+      it 'shows non-disabled index button without a warning' do
+        render
+
+        expect(rendered).to have_css('a.btn-success', text: button_text)
+        expect(rendered).not_to have_css('a.btn-success.disabled', text: button_text)
+        expect(rendered).not_to have_content(warning_msg)
+      end
+    end
+  end
+
   context 'when elasticsearch_aws_secret_access_key is not set' do
     let(:application_setting) { build(:application_setting) }
 

locale/gitlab.pot

@@ -14047,6 +14047,9 @@ msgstr ""
 msgid "Please create a username with only alphanumeric characters."
 msgstr ""
 
+msgid "Please create an index before enabling indexing"
+msgstr ""
+
 msgid "Please enable and migrate to hashed storage to avoid security issues and ensure data integrity. %{migrate_link}"
 msgstr ""