From a128482f1b9541a0c14f6ab58c0021e77e8120cb Mon Sep 17 00:00:00 2001
From: Chris Grindstaff <chris@gstaff.org>
Date: Thu, 11 Jul 2024 14:19:09 -0400
Subject: [PATCH] feat: enable ChangeLog plugin to monitor metric value change

---
 cmd/exporters/prometheus/prometheus.go      | 15 ++--
 cmd/exporters/prometheus/prometheus_test.go | 85 ++++++++++++++++++++-
 2 files changed, 87 insertions(+), 13 deletions(-)

diff --git a/cmd/exporters/prometheus/prometheus.go b/cmd/exporters/prometheus/prometheus.go
index 7b25546cb..2a2e3df81 100644
--- a/cmd/exporters/prometheus/prometheus.go
+++ b/cmd/exporters/prometheus/prometheus.go
@@ -342,16 +342,11 @@ func (p *Prometheus) render(data *matrix.Matrix) ([][]byte, exporter.Stats) {
 		// For example, it might indicate that 'volume_size_total' has been updated.
 		// If a global prefix for the exporter is defined, we need to amend the metric name with this prefix.
 		if p.globalPrefix != "" && data.Object == changelog.ObjectChangeLog {
-			categoryIsMetric := false
-			for label, value := range instance.GetLabels() {
-				if label == changelog.Category && value == changelog.Metric {
-					categoryIsMetric = true
-					break
-				}
-			}
-			if categoryIsMetric {
-				if value, ok := instance.GetLabels()[changelog.Track]; ok {
-					instance.GetLabels()[changelog.Track] = p.globalPrefix + value
+			if categoryValue, ok := instance.GetLabels()[changelog.Category]; ok {
+				if categoryValue == changelog.Metric {
+					if tracked, ok := instance.GetLabels()[changelog.Track]; ok {
+						instance.GetLabels()[changelog.Track] = p.globalPrefix + tracked
+					}
 				}
 			}
 		}
diff --git a/cmd/exporters/prometheus/prometheus_test.go b/cmd/exporters/prometheus/prometheus_test.go
index e2af74ac0..34e67b9ed 100644
--- a/cmd/exporters/prometheus/prometheus_test.go
+++ b/cmd/exporters/prometheus/prometheus_test.go
@@ -6,6 +6,7 @@ package prometheus
 
 import (
 	"bytes"
+	"github.com/google/go-cmp/cmp"
 	"github.com/netapp/harvest/v2/cmd/poller/exporter"
 	"github.com/netapp/harvest/v2/cmd/poller/options"
 	"github.com/netapp/harvest/v2/pkg/conf"
@@ -88,6 +89,32 @@ func BenchmarkEscape(b *testing.B) {
 	}
 }
 
+func setUpChangeMatrix() *matrix.Matrix {
+	m := matrix.New("change", "change", "change")
+	// Create a metric with a metric value change
+	log, _ := m.NewMetricUint64("log")
+	instance, _ := m.NewInstance("A")
+	_ = log.SetValueInt64(instance, 3)
+	instance.SetLabel("category", "metric")
+	instance.SetLabel("cluster", "umeng-aff300-01-02")
+	instance.SetLabel("object", "volume")
+	instance.SetLabel("op", "metric_change")
+	instance.SetLabel("track", "volume_size_total")
+
+	// Create a metric with a label change
+	instance2, _ := m.NewInstance("B")
+	_ = log.SetValueInt64(instance2, 3)
+	instance2.SetLabel("category", "label")
+	instance2.SetLabel("cluster", "umeng-aff300-01-02")
+	instance2.SetLabel("new_value", "offline")
+	instance2.SetLabel("object", "volume")
+	instance2.SetLabel("old_value", "online")
+	instance2.SetLabel("op", "update")
+	instance2.SetLabel("track", "state")
+
+	return m
+}
+
 func setUpMatrix(object string) *matrix.Matrix {
 	m := matrix.New("bike", object, "bike")
 	speed, _ := m.NewMetricUint64("max_speed")
@@ -115,7 +142,7 @@ max_speed{} 3`},
 
 	for _, tt := range tests {
 		t.Run(tt.prefix, func(t *testing.T) {
-			p, err := setupPrometheusExporter()
+			p, err := setUpPrometheusExporter("")
 			if err != nil {
 				t.Errorf("expected nil, got %v", err)
 			}
@@ -142,14 +169,66 @@ max_speed{} 3`},
 	}
 }
 
-func setupPrometheusExporter() (exporter.Exporter, error) {
+func TestGlobalPrefixWithChangelog(t *testing.T) {
+
+	type test struct {
+		prefix string
+		want   string
+	}
+
+	tests := []test{
+		{"prefix", `
+netapp_change_log{category="label",cluster="umeng-aff300-01-02",new_value="offline",object="volume",old_value="online",op="update",track="state"} 3
+netapp_change_log{category="metric",cluster="umeng-aff300-01-02",object="volume",op="metric_change",track="netapp_volume_size_total"} 3`},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.prefix, func(t *testing.T) {
+			p, err := setUpPrometheusExporter("netapp")
+
+			if err != nil {
+				t.Errorf("expected nil, got %v", err)
+			}
+			m := setUpChangeMatrix()
+
+			_, err = p.Export(m)
+			if err != nil {
+				t.Errorf("expected nil, got %v", err)
+			}
+
+			prom := p.(*Prometheus)
+			var lines []string
+			for _, metrics := range prom.cache.Get() {
+				for _, metric := range metrics {
+					lines = append(lines, string(metric))
+				}
+			}
+
+			slices.Sort(lines)
+			diff := cmp.Diff(strings.TrimSpace(tt.want), strings.Join(lines, "\n"))
+			if diff != "" {
+				t.Errorf("Mismatch (-got +want):\n%s", diff)
+			}
+		})
+	}
+}
+
+func setUpPrometheusExporter(prefix string) (exporter.Exporter, error) {
+
 	absExp := exporter.New(
 		"Prometheus",
 		"prom1",
 		&options.Options{PromPort: 1},
-		conf.Exporter{IsTest: true},
+		conf.Exporter{
+			IsTest:     true,
+			SortLabels: true,
+		},
 		nil,
 	)
+
+	if prefix != "" {
+		absExp.Params.GlobalPrefix = &prefix
+	}
 	p := New(absExp)
 	err := p.Init()
 	return p, err