Make the metric interval optional

- set default value to 1m

pkg/apis/flagger/v1alpha3/types.go

@@ -27,6 +27,7 @@ const (
 	CanaryKind              = "Canary"
 	ProgressDeadlineSeconds = 600
 	AnalysisInterval        = 60 * time.Second
+	MetricInterval          = "1m"
 )
 
 // +genclient
@@ -128,7 +129,7 @@ type CanaryAnalysis struct {
 // CanaryMetric holds the reference to Istio metrics used for canary analysis
 type CanaryMetric struct {
 	Name      string  `json:"name"`
-	Interval  string  `json:"interval"`
+	Interval  string  `json:"interval,omitempty"`
 	Threshold float64 `json:"threshold"`
 	// +optional
 	Query string `json:"query,omitempty"`
@@ -172,3 +173,8 @@ func (c *Canary) GetAnalysisInterval() time.Duration {
 
 	return interval
 }
+
+// GetMetricInterval returns the metric interval default value (1m)
+func (c *Canary) GetMetricInterval() string {
+	return MetricInterval
+}