Fixed creating retention policies

Rakefile

@@ -15,8 +15,17 @@ QUERIES = File.expand_path('../queries', __FILE__)
 desc 'Sets up the retention policies'
 task :policies do
-  CLIENT.query('CREATE RETENTION POLICY "default" ON gitlab DURATION 1h REPLICATION 1 DEFAULT')
-  CLIENT.query('CREATE RETENTION POLICY downsampled ON gitlab DURATION 7d REPLICATION 1')
+  db = ENV.fetch('INFLUX_DATABASE')
+
+  existing = CLIENT.list_retention_policies(db).map { |h| h['name'] }
+
+  unless existing.include?('default')
+    CLIENT.create_retention_policy('default', db, '1h', 1, true)
+  end
+
+  unless existing.include?('downsampled')
+    CLIENT.create_retention_policy('downsampled', db, '7d', 1)
+  end
 end
 desc 'Updates the continuous queries in the database'