feat(processors.unpivot): Add mode to create new metrics (#12659)

plugins/processors/unpivot/README.md

@@ -20,18 +20,37 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
 ```toml @sample.conf
 # Rotate multi field metric into several single field metrics
 [[processors.unpivot]]
+  ## Metric mode to pivot to
+  ## Set to "tag", metrics are pivoted as a tag and the metric is kept as
+  ## the original measurement name. Tag key name is set by tag_key value.
+  ## Set to "metric" creates a new metric named the field name. With this
+  ## option the tag_key is ignored. Be aware that this could lead to metric
+  ## name conflicts!
+  # use_fieldname_as = "tag"
+
   ## Tag to use for the name.
-  tag_key = "name"
+  # tag_key = "name"
+
   ## Field to use for the name of the value.
-  value_key = "value"
+  # value_key = "value"
 ```
 
 ## Example
 
+Metric mode `tag`:
+
 ```diff
 - cpu,cpu=cpu0 time_idle=42i,time_user=43i
 + cpu,cpu=cpu0,name=time_idle value=42i
 + cpu,cpu=cpu0,name=time_user value=43i
 ```
 
+Metric mode `metric`:
+
+```diff
+- cpu,cpu=cpu0 time_idle=42i,time_user=43i
++ time_idle,cpu=cpu0 value=42i
++ time_user,cpu=cpu0 value=43i
+```
+
 [pivot]: /plugins/processors/pivot/README.md

plugins/processors/unpivot/sample.conf

@@ -1,6 +1,15 @@
 # Rotate multi field metric into several single field metrics
 [[processors.unpivot]]
+  ## Metric mode to pivot to
+  ## Set to "tag", metrics are pivoted as a tag and the metric is kept as
+  ## the original measurement name. Tag key name is set by tag_key value.
+  ## Set to "metric" creates a new metric named the field name. With this
+  ## option the tag_key is ignored. Be aware that this could lead to metric
+  ## name conflicts!
+  # use_fieldname_as = "tag"
+
   ## Tag to use for the name.
-  tag_key = "name"
+  # tag_key = "name"
+
   ## Field to use for the name of the value.
-  value_key = "value"
+  # value_key = "value"

plugins/processors/unpivot/unpivot.go

@@ -3,6 +3,7 @@ package unpivot
 
 import (
 	_ "embed"
+	"fmt"
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/plugins/processors"
@@ -12,8 +13,9 @@ import (
 var sampleConfig string
 
 type Unpivot struct {
-	TagKey   string `toml:"tag_key"`
-	ValueKey string `toml:"value_key"`
+	FieldNameAs string `toml:"use_fieldname_as"`
+	TagKey      string `toml:"tag_key"`
+	ValueKey    string `toml:"value_key"`
 }
 
 func copyWithoutFields(metric telegraf.Metric) telegraf.Metric {
@@ -35,12 +37,30 @@ func (*Unpivot) SampleConfig() string {
 	return sampleConfig
 }
 
+func (p *Unpivot) Init() error {
+	switch p.FieldNameAs {
+	case "metric":
+	case "", "tag":
+		p.FieldNameAs = "tag"
+	default:
+		return fmt.Errorf("unrecognized metric mode: %q", p.FieldNameAs)
+	}
+
+	if p.TagKey == "" {
+		p.TagKey = "name"
+	}
+	if p.ValueKey == "" {
+		p.ValueKey = "value"
+	}
+
+	return nil
+}
+
 func (p *Unpivot) Apply(metrics ...telegraf.Metric) []telegraf.Metric {
 	fieldCount := 0
 	for _, m := range metrics {
 		fieldCount += len(m.FieldList())
 	}
-
 	results := make([]telegraf.Metric, 0, fieldCount)
 
 	for _, m := range metrics {
@@ -48,7 +68,14 @@ func (p *Unpivot) Apply(metrics ...telegraf.Metric) []telegraf.Metric {
 		for _, field := range m.FieldList() {
 			newMetric := base.Copy()
 			newMetric.AddField(p.ValueKey, field.Value)
-			newMetric.AddTag(p.TagKey, field.Key)
+
+			switch p.FieldNameAs {
+			case "metric":
+				newMetric.SetName(field.Key)
+			case "", "tag":
+				newMetric.AddTag(p.TagKey, field.Key)
+			}
+
 			results = append(results, newMetric)
 		}
 		m.Accept()

plugins/processors/unpivot/unpivot_test.go

@@ -6,9 +6,23 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/require"
 )
 
-func TestUnpivot(t *testing.T) {
+func TestUnpivot_defaults(t *testing.T) {
+	unpivot := &Unpivot{}
+	require.NoError(t, unpivot.Init())
+	require.Equal(t, "tag", unpivot.FieldNameAs)
+	require.Equal(t, "name", unpivot.TagKey)
+	require.Equal(t, "value", unpivot.ValueKey)
+}
+
+func TestUnpivot_invalidMetricMode(t *testing.T) {
+	unpivot := &Unpivot{FieldNameAs: "unknown"}
+	require.Error(t, unpivot.Init())
+}
+
+func TestUnpivot_originalMode(t *testing.T) {
 	now := time.Now()
 	tests := []struct {
 		name     string
@@ -88,3 +102,120 @@ func TestUnpivot(t *testing.T) {
 		})
 	}
 }
+
+func TestUnpivot_fieldMode(t *testing.T) {
+	now := time.Now()
+	tests := []struct {
+		name     string
+		unpivot  *Unpivot
+		metrics  []telegraf.Metric
+		expected []telegraf.Metric
+	}{
+		{
+			name: "simple",
+			unpivot: &Unpivot{
+				FieldNameAs: "metric",
+				TagKey:      "name",
+				ValueKey:    "value",
+			},
+			metrics: []telegraf.Metric{
+				testutil.MustMetric("cpu",
+					map[string]string{},
+					map[string]interface{}{
+						"idle_time": int64(42),
+					},
+					now,
+				),
+			},
+			expected: []telegraf.Metric{
+				testutil.MustMetric("idle_time",
+					map[string]string{},
+					map[string]interface{}{
+						"value": int64(42),
+					},
+					now,
+				),
+			},
+		},
+		{
+			name: "multi fields",
+			unpivot: &Unpivot{
+				FieldNameAs: "metric",
+				TagKey:      "name",
+				ValueKey:    "value",
+			},
+			metrics: []telegraf.Metric{
+				testutil.MustMetric("cpu",
+					map[string]string{},
+					map[string]interface{}{
+						"idle_time": int64(42),
+						"idle_user": int64(43),
+					},
+					now,
+				),
+			},
+			expected: []telegraf.Metric{
+				testutil.MustMetric("idle_time",
+					map[string]string{},
+					map[string]interface{}{
+						"value": int64(42),
+					},
+					now,
+				),
+				testutil.MustMetric("idle_user",
+					map[string]string{},
+					map[string]interface{}{
+						"value": int64(43),
+					},
+					now,
+				),
+			},
+		},
+		{
+			name: "multi fields and tags",
+			unpivot: &Unpivot{
+				FieldNameAs: "metric",
+				TagKey:      "name",
+				ValueKey:    "value",
+			},
+			metrics: []telegraf.Metric{
+				testutil.MustMetric("cpu",
+					map[string]string{
+						"building": "5a",
+					},
+					map[string]interface{}{
+						"idle_time": int64(42),
+						"idle_user": int64(43),
+					},
+					now,
+				),
+			},
+			expected: []telegraf.Metric{
+				testutil.MustMetric("idle_time",
+					map[string]string{
+						"building": "5a",
+					},
+					map[string]interface{}{
+						"value": int64(42),
+					},
+					now,
+				),
+				testutil.MustMetric("idle_user",
+					map[string]string{
+						"building": "5a",
+					},
+					map[string]interface{}{
+						"value": int64(43),
+					},
+					now,
+				),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			actual := tt.unpivot.Apply(tt.metrics...)
+			testutil.RequireMetricsEqual(t, tt.expected, actual, testutil.SortMetrics())
+		})
+	}
+}