chore: update custom metric label type (#1234)

* chore: update custom metric label type

* chore: fix lint

api/external/metrics.go

@@ -2,8 +2,24 @@ package external
 
 // +kubebuilder:object:generate=true
 type Metrics struct {
-	Name   string            `json:"name,omitempty" yaml:"name,omitempty"`
-	Labels map[string]string `json:"labels,omitempty" yaml:"labels,omitempty"`
-	Type   string            `json:"type,omitempty" yaml:"type,omitempty"`
-	Value  string            `json:"value,omitempty" yaml:"value,omitempty"`
+	Name   string       `json:"name,omitempty" yaml:"name,omitempty"`
+	Labels MetricLabels `json:"labels,omitempty" yaml:"labels,omitempty"`
+	Type   string       `json:"type,omitempty" yaml:"type,omitempty"`
+	Value  string       `json:"value,omitempty" yaml:"value,omitempty"`
+}
+
+type MetricLabels []MetricLabel
+
+type MetricLabel struct {
+	Name      string `json:"name"`
+	Value     string `json:"value,omitempty"`
+	ValueExpr string `json:"valueExpr,omitempty"`
+}
+
+func (labels MetricLabels) Names() []string {
+	var names []string
+	for _, k := range labels {
+		names = append(names, k.Name)
+	}
+	return names
 }

checks/metrics.go

@@ -2,7 +2,6 @@ package checks
 
 import (
 	"encoding/json"
-	"sort"
 	"strconv"
 
 	"github.com/flanksource/canary-checker/api/context"
@@ -14,41 +13,23 @@ import (
 
 var collectorMap = make(map[string]prometheus.Collector)
 
-func promLabelsOrderedKeys(labels map[string]string) []string {
-	var keys []string
-	for k := range labels {
-		keys = append(keys, k)
-	}
-	sort.Strings(keys)
-	return keys
-}
-
-func promLabelsOrderedVals(labels map[string]string) []string {
-	var vals []string
-	keys := promLabelsOrderedKeys(labels)
-	for _, k := range keys {
-		vals = append(vals, labels[k])
-	}
-	return vals
-}
-
-func addPrometheusMetric(name, metricType string, labels map[string]string) prometheus.Collector {
+func addPrometheusMetric(name, metricType string, labelNames []string) prometheus.Collector {
 	var collector prometheus.Collector
 	switch metricType {
 	case "histogram":
 		collector = prometheus.NewHistogramVec(
 			prometheus.HistogramOpts{Name: name},
-			promLabelsOrderedKeys(labels),
+			labelNames,
 		)
 	case "counter":
 		collector = prometheus.NewCounterVec(
 			prometheus.CounterOpts{Name: name},
-			promLabelsOrderedKeys(labels),
+			labelNames,
 		)
 	case "gauge":
 		collector = prometheus.NewGaugeVec(
 			prometheus.GaugeOpts{Name: name},
-			promLabelsOrderedKeys(labels),
+			labelNames,
 		)
 	default:
 		return nil
@@ -73,7 +54,7 @@ func exportCheckMetrics(ctx *context.Context, results pkg.Results) {
 			var collector prometheus.Collector
 			var exists bool
 			if collector, exists = collectorMap[spec.Name]; !exists {
-				collector = addPrometheusMetric(spec.Name, spec.Type, spec.Labels)
+				collector = addPrometheusMetric(spec.Name, spec.Type, spec.Labels.Names())
 				if collector == nil {
 					logger.Errorf("Invalid type for check.metrics %s for check[%s]", spec.Type, r.Check.GetName())
 					continue
@@ -114,16 +95,19 @@ func exportCheckMetrics(ctx *context.Context, results pkg.Results) {
 				logger.Errorf("Error converting value %s to float for check.metrics template %s for check[%s]: %v", valRaw, spec.Value, r.Check.GetName(), err)
 				continue
 			}
-			tplLabels := make(map[string]string)
-			for labelKey, labelVal := range spec.Labels {
-				label, err := template(ctx.New(templateInput), v1.Template{Expression: labelVal})
-				if err != nil {
-					logger.Errorf("Error templating label %s:%s for check.metrics for check[%s]: %v", labelKey, labelVal, r.Check.GetName(), err)
-					continue
+
+			var orderedLabelVals []string
+			for _, label := range spec.Labels {
+				val := label.Value
+				if label.ValueExpr != "" {
+					var err error
+					val, err = template(ctx.New(templateInput), v1.Template{Expression: label.ValueExpr})
+					if err != nil {
+						logger.Errorf("Error templating label %s:%s for check.metrics for check[%s]: %v", label.Name, label.ValueExpr, r.Check.GetName(), err)
+					}
 				}
-				tplLabels[labelKey] = label
+				orderedLabelVals = append(orderedLabelVals, val)
 			}
-			orderedLabelVals := promLabelsOrderedVals(tplLabels)
 
 			switch collector := collector.(type) {
 			case *prometheus.HistogramVec: