Merge pull request #87 from prometheus-community/superq/collect_param

SuperQ · web-flow · commit dc04cd8015ff · 2020-05-12T17:05:52.000+02:00
Add metrics prefix collect URL param
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## master / unreleased
 
+* [FEATURE] Add metrics prefix collect URL param
+
 ## 0.7.0 / 2020-05-01
 
 * [CHANGE] Remove deprecated `monitoring.New()` use. #76
diff --git a/README.md b/README.md
@@ -107,6 +107,20 @@ stackdriver_exporter \
   --monitoring.metrics-type-prefixes "compute.googleapis.com/instance/cpu,compute.googleapis.com/instance/disk"
 ```
 
+## Filtering enabled collectors
+
+The `stackdriver_exporter` collects all metrics type prefixes by default.
+
+For advanced uses, the collection can be filtered by using a repeatable URL param called `collect[]`. In the Prometheus configuration you can use you can use this syntax under the [scrape config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#<scrape_config>).
+
+
+```yaml
+params:
+  collect[]:
+  - compute.googleapis.com/instance/cpu
+  - compute.googleapis.com/instance/disk
+```
+
 ## Contributing
 
 Refer to the [contributing guidelines][contributing].
diff --git a/collectors/monitoring_collector.go b/collectors/monitoring_collector.go
@@ -72,7 +72,7 @@ type MonitoringCollector struct {
 	monitoringDropDelegatedProjects bool
 }
 
-func NewMonitoringCollector(monitoringService *monitoring.Service) (*MonitoringCollector, error) {
+func NewMonitoringCollector(monitoringService *monitoring.Service, filters map[string]bool) (*MonitoringCollector, error) {
 	if *projectID == "" {
 		return nil, errors.New("Flag `google.project-id` is required")
 	}
@@ -141,9 +141,20 @@ func NewMonitoringCollector(monitoringService *monitoring.Service) (*MonitoringC
 		},
 	)
 
+	metricsTypePrefixes := strings.Split(*monitoringMetricsTypePrefixes, ",")
+	filteredPrefixes := metricsTypePrefixes
+	if len(filters) > 0 {
+		filteredPrefixes = nil
+		for _, prefix := range metricsTypePrefixes {
+			if filters[prefix] {
+				filteredPrefixes = append(filteredPrefixes, prefix)
+			}
+		}
+	}
+
 	monitoringCollector := &MonitoringCollector{
 		projectID:                       *projectID,
-		metricsTypePrefixes:             strings.Split(*monitoringMetricsTypePrefixes, ","),
+		metricsTypePrefixes:             filteredPrefixes,
 		metricsInterval:                 *monitoringMetricsInterval,
 		metricsOffset:                   *monitoringMetricsOffset,
 		monitoringService:               monitoringService,
diff --git a/stackdriver_exporter.go b/stackdriver_exporter.go
@@ -90,6 +90,34 @@ func createMonitoringService() (*monitoring.Service, error) {
 	return monitoringService, nil
 }
 
+func newHandler(m *monitoring.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		collectParams := r.URL.Query()["collect[]"]
+
+		// Create filters for "collect[]" query parameters.
+		filters := make(map[string]bool)
+		for _, param := range collectParams {
+			filters[param] = true
+		}
+
+		monitoringCollector, err := collectors.NewMonitoringCollector(m, filters)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		registry := prometheus.NewRegistry()
+		registry.MustRegister(monitoringCollector)
+
+		gatherers := prometheus.Gatherers{
+			prometheus.DefaultGatherer,
+			registry,
+		}
+		// Delegate http serving to Prometheus client library, which will call collector.Collect.
+		h := promhttp.HandlerFor(gatherers, promhttp.HandlerOpts{})
+		h.ServeHTTP(w, r)
+	}
+}
+
 func main() {
 	log.AddFlags(kingpin.CommandLine)
 	kingpin.Version(version.Print("stackdriver_exporter"))
@@ -104,13 +132,9 @@ func main() {
 		log.Fatal(err)
 	}
 
-	monitoringCollector, err := collectors.NewMonitoringCollector(monitoringService)
-	if err != nil {
-		log.Fatal(err)
-	}
-	prometheus.MustRegister(monitoringCollector)
+	handlerFunc := newHandler(monitoringService)
 
-	http.Handle(*metricsPath, promhttp.Handler())
+	http.Handle(*metricsPath, promhttp.InstrumentMetricHandler(prometheus.DefaultRegisterer, handlerFunc))
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`<html>
              <head><title>Stackdriver Exporter</title></head>
