Advanced Search: Fix inaccessible ES server error

Changelog: fixed
EE: true

ee/app/models/elastic/migration_record.rb

@@ -37,7 +37,8 @@ module Elastic
 
     def load_from_index
       client.get(index: index_name, id: version)
-    rescue Elasticsearch::Transport::Transport::Errors::NotFound
+    rescue StandardError => e
+      logger.error("[Elastic::MigrationRecord]: #{e.class}: #{e.message}")
       nil
     end
 
@@ -64,7 +65,7 @@ module Elastic
             .search(index: helper.migrations_index_name, body: { query: { term: { completed: completed } }, size: ELASTICSEARCH_SIZE })
             .dig('hits', 'hits')
             .map { |v| v['_id'].to_i }
-    rescue Elasticsearch::Transport::Transport::Errors::NotFound
+    rescue StandardError
       []
     end
 
@@ -103,5 +104,9 @@ module Elastic
     def helper
       Gitlab::Elastic::Helper.default
     end
+
+    def logger
+      @logger ||= ::Gitlab::Elasticsearch::Logger.build
+    end
   end
 end

ee/spec/models/elastic/migration_record_spec.rb

@@ -41,6 +41,20 @@ RSpec.describe Elastic::MigrationRecord, :elastic do
     end
   end
 
+  describe '#load_from_index' do
+    it 'does not raise an exeption when connection refused' do
+      allow(Gitlab::Elastic::Helper.default).to receive(:get).and_raise(Faraday::ConnectionFailed)
+
+      expect(record.load_from_index).to be_nil
+    end
+
+    it 'does not raise an exeption when record does not exist' do
+      allow(Gitlab::Elastic::Helper.default).to receive(:get).and_raise(Elasticsearch::Transport::Transport::Errors::NotFound)
+
+      expect(record.load_from_index).to be_nil
+    end
+  end
+
   describe '#halt!' do
     it 'sets state for halted and halted_indexing_unpaused' do
       record.halt!
@@ -87,6 +101,13 @@ RSpec.describe Elastic::MigrationRecord, :elastic do
       expect(described_class.load_versions(completed: true)).to eq([])
       expect(described_class.load_versions(completed: false)).to eq([])
     end
+
+    it 'returns empty array when exception is raised' do
+      allow(Gitlab::Elastic::Helper.default.client).to receive(:search).and_raise(Faraday::ConnectionFailed)
+
+      expect(described_class.load_versions(completed: true)).to eq([])
+      expect(described_class.load_versions(completed: false)).to eq([])
+    end
   end
 
   describe '#running?' do