Add pivot and unpivot processors (#5991)

plugins/processors/pivot/pivot.go

@@ -0,0 +1,54 @@
+package pivot
+
+import (
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/processors"
+)
+
+const (
+	description  = "Rotate a single valued metric into a multi field metric"
+	sampleConfig = `
+  ## Tag to use for naming the new field.
+  tag_key = "name"
+  ## Field to use as the value of the new field.
+  value_key = "value"
+`
+)
+
+type Pivot struct {
+	TagKey   string `toml:"tag_key"`
+	ValueKey string `toml:"value_key"`
+}
+
+func (p *Pivot) SampleConfig() string {
+	return sampleConfig
+}
+
+func (p *Pivot) Description() string {
+	return description
+}
+
+func (p *Pivot) Apply(metrics ...telegraf.Metric) []telegraf.Metric {
+	for _, m := range metrics {
+		key, ok := m.GetTag(p.TagKey)
+		if !ok {
+			continue
+		}
+
+		value, ok := m.GetField(p.ValueKey)
+		if !ok {
+			continue
+		}
+
+		m.RemoveTag(p.TagKey)
+		m.RemoveField(p.ValueKey)
+		m.AddField(key, value)
+	}
+	return metrics
+}
+
+func init() {
+	processors.Add("pivot", func() telegraf.Processor {
+		return &Pivot{}
+	})
+}