Support tags in enum processor (influxdata#5855)

plugins/processors/enum/README.md

@@ -1,13 +1,13 @@
 # Enum Processor Plugin
 
-The Enum Processor allows the configuration of value mappings for metric fields.
+The Enum Processor allows the configuration of value mappings for metric tags or fields.
 The main use-case for this is to rewrite status codes such as _red_, _amber_ and
 _green_ by numeric values such as 0, 1, 2. The plugin supports string and bool
-types for the field values. Multiple Fields can be configured with separate
-value mappings for each field. Default mapping values can be configured to be
+types for the field values. Multiple tags or fields can be configured with separate
+value mappings for each. Default mapping values can be configured to be
 used for all values, which are not contained in the value_mappings. The
-processor supports explicit configuration of a destination field. By default the
-source field is overwritten.
+processor supports explicit configuration of a destination tag or field. By default the
+source tag or field is overwritten.
 
 ### Configuration:
 
@@ -17,8 +17,11 @@ source field is overwritten.
     ## Name of the field to map
     field = "status"
 
-    ## Destination field to be used for the mapped value.  By default the source
-    ## field is used, overwriting the original value.
+    ## Name of the tag to map
+    # tag = "status"
+
+    ## Destination tag or field to be used for the mapped value.  By default the
+    ## source tag or field is used, overwriting the original value.
     dest = "status_code"
 
     ## Default value to be used for all values not contained in the mapping

plugins/processors/enum/enum.go

@@ -1,6 +1,7 @@
 package enum
 
 import (
+	"fmt"
 	"strconv"
 
 	"github.com/influxdata/telegraf"
@@ -12,9 +13,12 @@ var sampleConfig = `
     ## Name of the field to map
     field = "status"
 
-    ## Destination field to be used for the mapped value.  By default the source
-    ## field is used, overwriting the original value.
-    # dest = "status_code"
+    ## Name of the tag to map
+    # tag = "status"
+
+    ## Destination tag or field to be used for the mapped value.  By default the
+    ## source tag or field is used, overwriting the original value.
+    dest = "status_code"
 
     ## Default value to be used for all values not contained in the mapping
     ## table.  When unset, the unmodified value for the field will be used if no
@@ -24,7 +28,7 @@ var sampleConfig = `
     ## Table of mappings
     [processors.enum.mapping.value_mappings]
       green = 1
-      yellow = 2
+      amber = 2
       red = 3
 `
 
@@ -33,6 +37,7 @@ type EnumMapper struct {
 }
 
 type Mapping struct {
+	Tag           string
 	Field         string
 	Dest          string
 	Default       interface{}
@@ -56,10 +61,24 @@ func (mapper *EnumMapper) Apply(in ...telegraf.Metric) []telegraf.Metric {
 
 func (mapper *EnumMapper) applyMappings(metric telegraf.Metric) telegraf.Metric {
 	for _, mapping := range mapper.Mappings {
-		if originalValue, isPresent := metric.GetField(mapping.Field); isPresent == true {
-			if adjustedValue, isString := adjustBoolValue(originalValue).(string); isString == true {
-				if mappedValue, isMappedValuePresent := mapping.mapValue(adjustedValue); isMappedValuePresent == true {
-					writeField(metric, mapping.getDestination(), mappedValue)
+		if mapping.Field != "" {
+			if originalValue, isPresent := metric.GetField(mapping.Field); isPresent {
+				if adjustedValue, isString := adjustBoolValue(originalValue).(string); isString {
+					if mappedValue, isMappedValuePresent := mapping.mapValue(adjustedValue); isMappedValuePresent {
+						writeField(metric, mapping.getDestination(), mappedValue)
+					}
+				}
+			}
+		}
+		if mapping.Tag != "" {
+			if originalValue, isPresent := metric.GetTag(mapping.Tag); isPresent {
+				if mappedValue, isMappedValuePresent := mapping.mapValue(originalValue); isMappedValuePresent {
+					switch val := mappedValue.(type) {
+					case string:
+						writeTag(metric, mapping.getDestinationTag(), val)
+					default:
+						writeTag(metric, mapping.getDestinationTag(), fmt.Sprintf("%v", val))
+					}
 				}
 			}
 		}
@@ -91,11 +110,23 @@ func (mapping *Mapping) getDestination() string {
 	return mapping.Field
 }
 
+func (mapping *Mapping) getDestinationTag() string {
+	if mapping.Dest != "" {
+		return mapping.Dest
+	}
+	return mapping.Tag
+}
+
 func writeField(metric telegraf.Metric, name string, value interface{}) {
 	metric.RemoveField(name)
 	metric.AddField(name, value)
 }
 
+func writeTag(metric telegraf.Metric, name string, value string) {
+	metric.RemoveTag(name)
+	metric.AddTag(name, value)
+}
+
 func init() {
 	processors.Add("enum", func() telegraf.Processor {
 		return &EnumMapper{}

plugins/processors/enum/enum_test.go

@@ -27,12 +27,23 @@ func calculateProcessedValues(mapper EnumMapper, metric telegraf.Metric) map[str
 	return processed[0].Fields()
 }
 
+func calculateProcessedTags(mapper EnumMapper, metric telegraf.Metric) map[string]string {
+	processed := mapper.Apply(metric)
+	return processed[0].Tags()
+}
+
 func assertFieldValue(t *testing.T, expected interface{}, field string, fields map[string]interface{}) {
 	value, present := fields[field]
 	assert.True(t, present, "value of field '"+field+"' was not present")
 	assert.EqualValues(t, expected, value)
 }
 
+func assertTagValue(t *testing.T, expected interface{}, tag string, tags map[string]string) {
+	value, present := tags[tag]
+	assert.True(t, present, "value of tag '"+tag+"' was not present")
+	assert.EqualValues(t, expected, value)
+}
+
 func TestRetainsMetric(t *testing.T) {
 	mapper := EnumMapper{}
 	source := createTestMetric()
@@ -56,6 +67,14 @@ func TestMapsSingleStringValue(t *testing.T) {
 	assertFieldValue(t, 1, "string_value", fields)
 }
 
+func TestMapsSingleStringValueTag(t *testing.T) {
+	mapper := EnumMapper{Mappings: []Mapping{{Tag: "tag", ValueMappings: map[string]interface{}{"tag_value": "valuable"}}}}
+
+	tags := calculateProcessedTags(mapper, createTestMetric())
+
+	assertTagValue(t, "valuable", "tag", tags)
+}
+
 func TestNoFailureOnMappingsOnNonStringValuedFields(t *testing.T) {
 	mapper := EnumMapper{Mappings: []Mapping{{Field: "int_value", ValueMappings: map[string]interface{}{"13i": int64(7)}}}}