Add a flag to publish metrics with high resolution (#32)

So far, this tool is only publishing metrics with high resolution when
the original prometheus metrics have the label __cw_high_res.

However, in our case we're running exporters and prom-to-cloudwatch
as sidecars of ECS tasks. This tool being directly connected to the
exporters, we can't add the high res label.

Author: Albin Kerouanton

main.go

@@ -15,6 +15,8 @@ import (
 	"github.com/gobwas/glob"
 )
 
+var defaultForceHighRes, _ = strconv.ParseBool(os.Getenv("FORCE_HIGH_RES"))
+
 var (
 	awsAccessKeyId              = flag.String("aws_access_key_id", os.Getenv("AWS_ACCESS_KEY_ID"), "AWS access key Id with permissions to publish CloudWatch metrics")
 	awsSecretAccessKey          = flag.String("aws_secret_access_key", os.Getenv("AWS_SECRET_ACCESS_KEY"), "AWS secret access key with permissions to publish CloudWatch metrics")
@@ -33,6 +35,7 @@ var (
 	excludeMetrics              = flag.String("exclude_metrics", os.Getenv("EXCLUDE_METRICS"), "Never publish the specified metrics (comma-separated list of glob patterns, e.g. 'tomcat_*')")
 	includeDimensionsForMetrics = flag.String("include_dimensions_for_metrics", os.Getenv("INCLUDE_DIMENSIONS_FOR_METRICS"), "Only publish the specified dimensions for metrics (semi-colon-separated key values of comma-separated dimensions of METRIC=dim1,dim2;, e.g. 'flink_jobmanager=job_id')")
 	excludeDimensionsForMetrics = flag.String("exclude_dimensions_for_metrics", os.Getenv("EXCLUDE_DIMENSIONS_FOR_METRICS"), "Never publish the specified dimensions for metrics (semi-colon-separated key values of comma-separated dimensions of METRIC=dim1,dim2;, e.g. 'flink_jobmanager=job,host;zk_up=host,pod;')")
+	forceHighRes                = flag.Bool("force_high_res", defaultForceHighRes, "Publish all metrics with high resolution, even when original metrics don't have the label "+cwHighResLabel)
 )
 
 // kevValMustParse takes a string and exits with a message if it cannot parse as KEY=VALUE
@@ -180,6 +183,7 @@ func main() {
 		ExcludeMetrics:                excludeMetricsList,
 		ExcludeDimensionsForMetrics:   excludeDimensionsForMetricsList,
 		IncludeDimensionsForMetrics:   includeDimensionsForMetricsList,
+		ForceHighRes:                  *forceHighRes,
 	}
 
 	if *prometheusScrapeInterval != "" {

prometheus_to_cloudwatch.go

@@ -108,6 +108,9 @@ type Config struct {
 
 	// Exclude certain dimensions from the specified metrics
 	ExcludeDimensionsForMetrics []MatcherWithStringSet
+
+	// ForceHighRes forces all exported metrics to be sent as custom high-resolution metrics.
+	ForceHighRes bool
 }
 
 // Bridge pushes metrics to AWS CloudWatch
@@ -125,6 +128,7 @@ type Bridge struct {
 	excludeMetrics                []glob.Glob
 	includeDimensionsForMetrics   []MatcherWithStringSet
 	excludeDimensionsForMetrics   []MatcherWithStringSet
+	forceHighRes                  bool
 }
 
 // NewBridge initializes and returns a pointer to a Bridge using the
@@ -151,6 +155,7 @@ func NewBridge(c *Config) (*Bridge, error) {
 	b.excludeMetrics = c.ExcludeMetrics
 	b.includeDimensionsForMetrics = c.IncludeDimensionsForMetrics
 	b.excludeDimensionsForMetrics = c.ExcludeDimensionsForMetrics
+	b.forceHighRes = c.ForceHighRes
 
 	if c.CloudWatchPublishInterval > 0 {
 		b.cloudWatchPublishInterval = c.CloudWatchPublishInterval
@@ -327,7 +332,7 @@ func appendDatum(data []*cloudwatch.MetricDatum, name string, s *model.Sample, b
 		SetValue(value).
 		SetTimestamp(s.Timestamp.Time()).
 		SetDimensions(append(kubeStateDimensions, getAdditionalDimensions(b)...)).
-		SetStorageResolution(getResolution(metric)).
+		SetStorageResolution(b.getResolution(metric)).
 		SetUnit(getUnit(metric))
 	data = append(data, datum)
 
@@ -338,7 +343,7 @@ func appendDatum(data []*cloudwatch.MetricDatum, name string, s *model.Sample, b
 			SetValue(value).
 			SetTimestamp(s.Timestamp.Time()).
 			SetDimensions(append(replacedDimensions, getAdditionalDimensions(b)...)).
-			SetStorageResolution(getResolution(metric)).
+			SetStorageResolution(b.getResolution(metric)).
 			SetUnit(getUnit(metric))
 		data = append(data, replacedDimensionDatum)
 	}
@@ -465,7 +470,10 @@ func getAdditionalDimensions(b *Bridge) []*cloudwatch.Dimension {
 }
 
 // Returns 1 if the metric contains a __cw_high_res label, otherwise returns 60
-func getResolution(m model.Metric) int64 {
+func (b *Bridge) getResolution(m model.Metric) int64 {
+	if b.forceHighRes {
+		return 1
+	}
 	if _, ok := m[cwHighResLabel]; ok {
 		return 1
 	}