Fix database migrations when Redis is not running

lib/gitlab/current_settings.rb

@@ -9,10 +9,14 @@ module Gitlab
     end
 
     def ensure_application_settings!
-      settings = ::ApplicationSetting.cached
+      if connect_to_db?
+        begin
+          settings = ::ApplicationSetting.cached
+        # In case Redis isn't running or the Redis UNIX socket file is not available
+        rescue ::Redis::BaseError, ::Errno::ENOENT
+          settings = ::ApplicationSetting.last
+        end
 
-      if !settings && connect_to_db?
-        settings = ::ApplicationSetting.current
         settings ||= ::ApplicationSetting.create_from_defaults unless ActiveRecord::Migrator.needs_migration?
       end
 

spec/lib/gitlab/current_settings_spec.rb

+require 'spec_helper'
+
+describe Gitlab::CurrentSettings do
+  describe '#current_application_settings' do
+    it 'attempts to use cached values first' do
+      allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(true)
+      expect(ApplicationSetting).to receive(:cached).and_call_original
+      expect(ApplicationSetting).not_to receive(:last)
+
+      expect(current_application_settings).to be_a(ApplicationSetting)
+    end
+
+    it 'does not attempt to connect to DB or Redis' do
+      allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(false)
+      expect(ApplicationSetting).not_to receive(:current)
+      expect(ApplicationSetting).not_to receive(:last)
+
+      expect(current_application_settings).to eq fake_application_settings
+    end
+
+    it 'falls back to DB if Redis fails' do
+      allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(true)
+      expect(ApplicationSetting).to receive(:cached).and_raise(::Redis::BaseError)
+      expect(ApplicationSetting).to receive(:last).and_call_original
+
+      expect(current_application_settings).to be_a(ApplicationSetting)
+    end
+  end
+end