Allow non-integral X-Ray sampling rates (#803)

config.go

@@ -125,5 +125,5 @@ type Config struct {
 	} `yaml:"veneur_metrics_scopes"`
 	XrayAddress          string   `yaml:"xray_address"`
 	XrayAnnotationTags   []string `yaml:"xray_annotation_tags"`
-	XraySamplePercentage int      `yaml:"xray_sample_percentage"`
+	XraySamplePercentage float64  `yaml:"xray_sample_percentage"`
 }

example.yaml

@@ -412,11 +412,9 @@ signalfx_dynamic_per_tag_api_keys_refresh_period: "10m"
 xray_address: "localhost:2000"
 
 # Sample rate in percent (as an integer)
-# This should ideally be a floating point number, but at the time this was
-# written, gojson interpreted whole-number floats in yaml as integers.
 # The sink will hash the trace id of the span such that all Veneur instances
 # will sample the same segments by using the trace id as input for a checksum.
-xray_sample_percentage: 100
+xray_sample_percentage: 100.0
 
 # All tags are sent as (unindexed) Metadata to X-ray. Up to 50 tags per trace
 # (not per span) can be indexed as Annotations for search. Tag keys specified here

sinks/xray/xray.go

@@ -80,7 +80,7 @@ type XRaySpanSink struct {
 var _ sinks.SpanSink = &XRaySpanSink{}
 
 // NewXRaySpanSink creates a new instance of a XRaySpanSink.
-func NewXRaySpanSink(daemonAddr string, sampleRatePercentage int, commonTags map[string]string, annotationTags []string, log *logrus.Logger) (*XRaySpanSink, error) {
+func NewXRaySpanSink(daemonAddr string, sampleRatePercentage float64, commonTags map[string]string, annotationTags []string, log *logrus.Logger) (*XRaySpanSink, error) {
 
 	log.WithFields(logrus.Fields{
 		"Address": daemonAddr,