add monitoring.filters flag (#133)

* add monitoring.filters flag

Signed-off-by: vrunoa <vruno.alassia@gmail.com>

README.md

@@ -67,6 +67,7 @@ If you are still using the legacy [Access scopes][access-scopes], the `https://w
 | `monitoring.metrics-type-prefixes`<br />`STACKDRIVER_EXPORTER_MONITORING_METRICS_TYPE_PREFIXES` | Yes | | Comma separated Google Stackdriver Monitoring Metric Type prefixes (see [example][metrics-prefix-example] and [available metrics][metrics-list]) |
 | `monitoring.metrics-interval`<br />`STACKDRIVER_EXPORTER_MONITORING_METRICS_INTERVAL` | No | `5m` | Metric's timestamp interval to request from the Google Stackdriver Monitoring Metrics API. Only the most recent data point is used |
 | `monitoring.metrics-offset`<br />`STACKDRIVER_EXPORTER_MONITORING_METRICS_OFFSET` | No | `0s` | Offset (into the past) for the metric's timestamp interval to request from the Google Stackdriver Monitoring Metrics API, to handle latency in published metrics |
+| `monitoring.filters`| No | Empty list | Formatted string to allow filtering on certain metrics type |
 | `web.listen-address`<br />`STACKDRIVER_EXPORTER_WEB_LISTEN_ADDRESS` | No | `:9255` | Address to listen on for web interface and telemetry |
 | `web.telemetry-path`<br />`STACKDRIVER_EXPORTER_WEB_TELEMETRY_PATH` | No | `/metrics` | Path under which to expose Prometheus metrics |
 
@@ -107,6 +108,15 @@ stackdriver_exporter \
   --monitoring.metrics-type-prefixes "compute.googleapis.com/instance/cpu,compute.googleapis.com/instance/disk"
 ```
 
+Using extra filters:
+
+```
+stackdriver_exporter \
+ --google.project-id my-test-project \
+ --monitoring.metrics-type-prefixes='pubsub.googleapis.com/subscription' \
+ --monitoring.metrics-extra-filter='pubsub.googleapis.com/subscription:resource.labels.subscription_id=monitoring.regex.full_match("us-west4.*my-team-subs.*")'
+```
+
 ## Filtering enabled collectors
 
 The `stackdriver_exporter` collects all metrics type prefixes by default.

collectors/monitoring_collector.go

@@ -51,11 +51,20 @@ var (
 	monitoringDropDelegatedProjects = kingpin.Flag(
 		"monitoring.drop-delegated-projects", "Drop metrics from attached projects and fetch `project_id` only ($STACKDRIVER_EXPORTER_DROP_DELEGATED_PROJECTS).",
 	).Envar("STACKDRIVER_EXPORTER_DROP_DELEGATED_PROJECTS").Default("false").Bool()
+
+	monitoringMetricsExtraFilter = kingpin.Flag(
+		"monitoring.filters", "Filters. i.e: pubsub.googleapis.com/subscription:resource.labels.subscription_id=monitoring.regex.full_match(\"my-subs-prefix.*\")").Strings()
 )
 
+type MetricFilter struct {
+	Prefix   string
+	Modifier string
+}
+
 type MonitoringCollector struct {
 	projectID                       string
 	metricsTypePrefixes             []string
+	metricsFilters                  []MetricFilter
 	metricsInterval                 time.Duration
 	metricsOffset                   time.Duration
 	monitoringService               *monitoring.Service
@@ -145,10 +154,22 @@ func NewMonitoringCollector(projectID string, monitoringService *monitoring.Serv
 			}
 		}
 	}
+	var extraFilters []MetricFilter
+	for _, ef := range *monitoringMetricsExtraFilter {
+		efPrefix, efModifier := utils.GetExtraFilterModifiers(ef, ":")
+		if efPrefix != "" {
+			extraFilter := MetricFilter{
+				Prefix:   efPrefix,
+				Modifier: efModifier,
+			}
+			extraFilters = append(extraFilters, extraFilter)
+		}
+	}
 
 	monitoringCollector := &MonitoringCollector{
 		projectID:                       projectID,
 		metricsTypePrefixes:             filteredPrefixes,
+		metricsFilters:                  extraFilters,
 		metricsInterval:                 *monitoringMetricsInterval,
 		metricsOffset:                   *monitoringMetricsOffset,
 		monitoringService:               monitoringService,
@@ -238,6 +259,13 @@ func (c *MonitoringCollector) reportMonitoringMetrics(ch chan<- prometheus.Metri
 						c.projectID,
 						metricDescriptor.Type)
 				}
+				for _, ef := range c.metricsFilters {
+					if strings.Contains(metricDescriptor.Type, ef.Prefix) {
+						filter = fmt.Sprintf("%s AND (%s)", filter, ef.Modifier)
+					}
+				}
+
+				level.Debug(c.logger).Log("msg", "retrieving Google Stackdriver Monitoring metrics with filter", "filter", filter)
 				timeSeriesListCall := c.monitoringService.Projects.TimeSeries.List(utils.ProjectResource(c.projectID)).
 					Filter(filter).
 					IntervalStartTime(startTime.Format(time.RFC3339Nano)).

utils/utils.go

@@ -39,6 +39,14 @@ func NormalizeMetricName(metricName string) string {
 	return strings.Join(normalizedMetricName, "_")
 }
 
+func GetExtraFilterModifiers(extraFilter string, separator string) (string, string) {
+	mPrefix := strings.Split(extraFilter, separator)
+	if mPrefix[0] == extraFilter {
+		return "", ""
+	}
+	return mPrefix[0], strings.Join(mPrefix[1:], "")
+}
+
 func ProjectResource(projectID string) string {
 	return "projects/" + projectID
 }