Mark migration as requiring no downtime

+ Add spaces for four phases approach
+ fix InfluxDB rename

app/views/admin/application_settings/_form.html.haml

@@ -234,7 +234,7 @@
   %fieldset
     %legend Metrics - Influx
     %p
-      Setup Influx to measure a wide variety of statistics like the time spent
+      Setup InfluxDB to measure a wide variety of statistics like the time spent
       in running SQL queries. These settings require a
       = link_to 'restart', help_page_path('administration/restart_gitlab')
       to take effect.

config.ru

@@ -14,6 +14,7 @@ if defined?(Unicorn)
     use Unicorn::WorkerKiller::Oom, min, max
   end
 end
+
 # set default directory for multiproces metrics gathering
 ENV['prometheus_multiproc_dir'] ||= 'tmp/prometheus_data_dir'
 

db/migrate/20170519102115_add_prometheus_settings_to_metrics_settings.rb

@@ -2,6 +2,8 @@ class AddPrometheusSettingsToMetricsSettings < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
   disable_ddl_transaction!
 
+  DOWNTIME = false
+
   def up
     add_column_with_default(:application_settings, :prometheus_metrics_enabled, :boolean,
                             default: false, allow_null: false)

spec/controllers/metrics_controller_spec.rb

@@ -27,6 +27,7 @@ describe MetricsController do
 
       it 'returns DB ping metrics' do
         get :metrics
+
         expect(response.body).to match(/^db_ping_timeout 0$/)
         expect(response.body).to match(/^db_ping_success 1$/)
         expect(response.body).to match(/^db_ping_latency [0-9\.]+$/)
@@ -34,6 +35,7 @@ describe MetricsController do
 
       it 'returns Redis ping metrics' do
         get :metrics
+
         expect(response.body).to match(/^redis_ping_timeout 0$/)
         expect(response.body).to match(/^redis_ping_success 1$/)
         expect(response.body).to match(/^redis_ping_latency [0-9\.]+$/)
@@ -41,6 +43,7 @@ describe MetricsController do
 
       it 'returns file system check metrics' do
         get :metrics
+
         expect(response.body).to match(/^filesystem_access_latency{shard="default"} [0-9\.]+$/)
         expect(response.body).to match(/^filesystem_accessible{shard="default"} 1$/)
         expect(response.body).to match(/^filesystem_write_latency{shard="default"} [0-9\.]+$/)
@@ -56,6 +59,7 @@ describe MetricsController do
 
         it 'returns proper response' do
           get :metrics
+
           expect(response.status).to eq(404)
         end
       end
@@ -64,6 +68,7 @@ describe MetricsController do
     context 'without authorization token' do
       it 'returns proper response' do
         get :metrics
+
         expect(response.status).to eq(404)
       end
     end