Add Openstack metric service to Settings

Openstack Metrics capture service can be specified in settings.yml file.

Valid values are "gnocchi", "ceilometer". All other values means autodetection.

Related BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1421729

app/models/manageiq/providers/openstack/base_metrics_capture.rb

@@ -26,6 +26,10 @@ def perf_init_openstack
     raise "No EMS defined" if target.ext_management_system.nil?
 
     metering_service, = Benchmark.realtime_block(:connect) do
+      if available_metric_services.keys.include? metric_service_from_settings
+        $log.debug "#{_log.prefix} Using metrics provided by \"#{metric_service_from_settings}\" service, which was set in settings.yml."
+        return target.ext_management_system.connect(:service => available_metric_services[metric_service_from_settings])
+      end
       begin
         target.ext_management_system.connect(:service => "Metric")
       rescue Exception => ex
@@ -386,4 +390,15 @@ def parse_datetime(datetime)
     datetime << "Z" if datetime.size == 19
     Time.parse(datetime)
   end
+
+  def metric_service_from_settings
+    Settings[:workers][:worker_base][:queue_worker_base][:ems_metrics_collector_worker][:ems_metrics_openstack_default_service]
+  rescue StandardError => err
+    $log.warn "#{_log.prefix} Settings key ems_metrics_openstack_default_service is missing, #{err}."
+    nil
+  end
+
+  def available_metric_services
+    {"gnocchi" => "Metric", "ceilometer" => "Metering"}
+  end
 end

config/settings.yml

@@ -1306,6 +1306,7 @@
         :ems_metrics_collector_worker_openstack_network: {}
         :ems_metrics_collector_worker_redhat: {}
         :ems_metrics_collector_worker_vmware: {}
+        :ems_metrics_openstack_default_service: "auto"
       :ems_metrics_processor_worker:
         :count: 2
         :memory_threshold: 600.megabytes