pkg/metrics/providers: put comments on cloudWatchProvider methods

pkg/metrics/providers/cloudwatch.go

@@ -30,6 +30,8 @@ type cloudWatchClient interface {
 	GetMetricData(input *cloudwatch.GetMetricDataInput) (*cloudwatch.GetMetricDataOutput, error)
 }
 
+// newCloudWatchProvider takes a metricInterval, a provider spec and the credentials map, and
+// returns a cloudWatchProvider ready to execute queries against the AWS CloudWatch metrics
 func newCloudWatchProvider(metricInterval string, provider flaggerv1.MetricTemplateProvider) (*cloudWatchProvider, error) {
 	region := strings.TrimLeft(provider.Address, "monitoring.")
 	region = strings.TrimRight(region, ".amazonaws.com")
@@ -51,6 +53,8 @@ func newCloudWatchProvider(metricInterval string, provider flaggerv1.MetricTempl
 	}, err
 }
 
+// RunQuery executes the aws cloud watch metrics query against GetMetricsData endpoint
+// and returns the the first result as float64
 func (p *cloudWatchProvider) RunQuery(query string) (float64, error) {
 	var cq []*cloudwatch.MetricDataQuery
 	if err := json.Unmarshal([]byte(query), &cq); err != nil {
@@ -83,6 +87,10 @@ func (p *cloudWatchProvider) RunQuery(query string) (float64, error) {
 	return aws.Float64Value(vs[0]), nil
 }
 
+// IsOnline calls GetMetricsData endpoint with the empty query
+// and returns an error if the returned status code is NOT http.StatusBadRequests.
+// For example, if the flagger does not have permission to perform `cloudwatch:GetMetricsData`,
+// the returned status code would be http.StatusForbidden
 func (p *cloudWatchProvider) IsOnline() (bool, error) {
 	_, err := p.client.GetMetricData(&cloudwatch.GetMetricDataInput{
 		EndTime:           aws.Time(time.Time{}),

pkg/metrics/providers/datadog.go

@@ -45,7 +45,7 @@ type datadogResponse struct {
 	}
 }
 
-// newDatadogProvider takes a canary spec, a provider spec and the credentials map, and
+// newDatadogProvider takes a metricInterval, a provider spec and the credentials map, and
 // returns a Datadog client ready to execute queries against the API
 func newDatadogProvider(metricInterval string,
 	provider flaggerv1.MetricTemplateProvider,