Set the name of k8s cluster in Stackdriver sink.

Author: kawych

docs/sink-configuration.md

@@ -37,6 +37,17 @@ The following options are available:
 * `withfields` - Use [InfluxDB fields](storage-schema.md#using-fields) (default: `false`)
 * `cluster_name` - cluster name for different Kubernetes clusters. (default: `default`)
 
+### Stackdriver
+
+This sink supports monitoring metrics only.
+To use the Stackdriver sink add following flag:
+
+	--sink=stackdriver[:?<STACKDRIVER_OPTIONS>]
+
+The following options are available:
+* `workers` - The number of workers. (default: `1`)
+* `cluster_name` - Cluster name for different Kubernetes clusters. (default: ``)
+
 ### Google Cloud Monitoring
 This sink supports monitoring metrics only.
 To use the GCM sink add the following flag:

metrics/sinks/stackdriver/stackdriver.go

@@ -38,6 +38,7 @@ const (
 
 type StackdriverSink struct {
 	project           string
+	cluster           string
 	zone              string
 	stackdriverClient *sd_api.Service
 	requestQueue      chan *sd_api.CreateTimeSeriesRequest
@@ -223,6 +224,11 @@ func CreateStackdriverSink(uri *url.URL) (core.DataSink, error) {
 		workers = 1
 	}
 
+	cluster_name := ""
+	if len(opts["cluster_name"]) >= 1 {
+		cluster_name = opts["cluster_name"][0]
+	}
+
 	if err := gce_util.EnsureOnGCE(); err != nil {
 		return nil, err
 	}
@@ -250,6 +256,7 @@ func CreateStackdriverSink(uri *url.URL) (core.DataSink, error) {
 
 	sink := &StackdriverSink{
 		project:           projectId,
+		cluster:           cluster_name,
 		zone:              zone,
 		stackdriverClient: stackdriverClient,
 		requestQueue:      requestQueue,
@@ -408,7 +415,7 @@ func (sink *StackdriverSink) TranslateMetric(timestamp time.Time, labels map[str
 func (sink *StackdriverSink) getResourceLabels(labels map[string]string) map[string]string {
 	return map[string]string{
 		"project_id":     sink.project,
-		"cluster_name":   "",
+		"cluster_name":   sink.cluster,
 		"zone":           sink.zone,
 		"instance_id":    labels[core.LabelHostID.Key],
 		"namespace_id":   labels[core.LabelPodNamespaceUID.Key],