Use operation subtables in enum and rename processors (#4672)

plugins/processors/rename/README.md

@@ -5,28 +5,23 @@ The `rename` processor renames measurements, fields, and tags.
 ### Configuration:
 
 ```toml
-## Measurement, tag, and field renamings are stored in separate sub-tables.
-## Specify one sub-table per rename operation.
 [[processors.rename]]
-[[processors.rename.measurement]]
-  ## measurement to change
-  from = "network_interface_throughput"
-  to = "throughput"
+  ## Specify one sub-table per rename operation.
+  [[processors.rename.replace]]
+    measurement = "network_interface_throughput"
+    dest = "throughput"
 
-[[processors.rename.tag]]
-  ## tag to change
-  from = "hostname"
-  to = "host"
+  [[processors.rename.replace]]
+    tag = "hostname"
+    dest = "host"
 
-[[processors.rename.field]]
-  ## field to change
-  from = "lower"
-  to = "min"
+  [[processors.rename.replace]]
+    field = "lower"
+    dest = "min"
 
-[[processors.rename.field]]
-  ## field to change
-  from = "upper"
-  to = "max"
+  [[processors.rename.replace]]
+    field = "upper"
+    dest = "max"
 ```
 
 ### Tags:
@@ -36,6 +31,6 @@ No tags are applied by this processor, though it can alter them by renaming.
 ### Example processing:
 
 ```diff
-- network_interface_throughput,hostname=backend.example.com,units=kbps lower=10i,upper=1000i,mean=500i 1502489900000000000
-+ throughput,host=backend.example.com,units=kbps min=10i,max=1000i,mean=500i 1502489900000000000
+- network_interface_throughput,hostname=backend.example.com lower=10i,upper=1000i,mean=500i 1502489900000000000
++ throughput,host=backend.example.com min=10i,max=1000i,mean=500i 1502489900000000000
 ```

plugins/processors/rename/rename.go

@@ -6,38 +6,17 @@ import (
 )
 
 const sampleConfig = `
-  ## Measurement, tag, and field renamings are stored in separate sub-tables.
-  ## Specify one sub-table per rename operation.
-  # [[processors.rename.measurement]]
-  #   ## measurement to change
-  #   from = "kilobytes_per_second"
-  #   to = "kbps"
-
-  # [[processors.rename.tag]]
-  #   ## tag to change
-  #   from = "host"
-  #   to = "hostname"
-
-  # [[processors.rename.field]]
-  #   ## field to change
-  #   from = "lower"
-  #   to = "min"
-
-  # [[processors.rename.field]]
-  #   ## field to change
-  #   from = "upper"
-  #   to = "max"
 `
 
-type renamer struct {
-	From string
-	To   string
+type Replace struct {
+	Measurement string `toml:"measurement"`
+	Tag         string `toml:"tag"`
+	Field       string `toml:"field"`
+	Dest        string `toml:"dest"`
 }
 
 type Rename struct {
-	Measurement []renamer
-	Tag         []renamer
-	Field       []renamer
+	Replaces []Replace `toml:"replace"`
 }
 
 func (r *Rename) SampleConfig() string {
@@ -50,24 +29,32 @@ func (r *Rename) Description() string {
 
 func (r *Rename) Apply(in ...telegraf.Metric) []telegraf.Metric {
 	for _, point := range in {
-		for _, measurementRenamer := range r.Measurement {
-			if point.Name() == measurementRenamer.From {
-				point.SetName(measurementRenamer.To)
-				break
+		for _, replace := range r.Replaces {
+			if replace.Dest == "" {
+				continue
 			}
-		}
 
-		for _, tagRenamer := range r.Tag {
-			if value, ok := point.GetTag(tagRenamer.From); ok {
-				point.RemoveTag(tagRenamer.From)
-				point.AddTag(tagRenamer.To, value)
+			if replace.Measurement != "" {
+				if value := point.Name(); value == replace.Measurement {
+					point.SetName(replace.Dest)
+				}
+				continue
 			}
-		}
 
-		for _, fieldRenamer := range r.Field {
-			if value, ok := point.GetField(fieldRenamer.From); ok {
-				point.RemoveField(fieldRenamer.From)
-				point.AddField(fieldRenamer.To, value)
+			if replace.Tag != "" {
+				if value, ok := point.GetTag(replace.Tag); ok {
+					point.RemoveTag(replace.Tag)
+					point.AddTag(replace.Dest, value)
+				}
+				continue
+			}
+
+			if replace.Field != "" {
+				if value, ok := point.GetField(replace.Field); ok {
+					point.RemoveField(replace.Field)
+					point.AddField(replace.Dest, value)
+				}
+				continue
 			}
 		}
 	}

plugins/processors/rename/rename_test.go

@@ -21,10 +21,11 @@ func newMetric(name string, tags map[string]string, fields map[string]interface{
 }
 
 func TestMeasurementRename(t *testing.T) {
-	r := Rename{}
-	r.Measurement = []renamer{
-		{From: "foo", To: "bar"},
-		{From: "baz", To: "quux"},
+	r := Rename{
+		Replaces: []Replace{
+			{Measurement: "foo", Dest: "bar"},
+			{Measurement: "baz", Dest: "quux"},
+		},
 	}
 	m1 := newMetric("foo", nil, nil)
 	m2 := newMetric("bar", nil, nil)
@@ -36,9 +37,10 @@ func TestMeasurementRename(t *testing.T) {
 }
 
 func TestTagRename(t *testing.T) {
-	r := Rename{}
-	r.Tag = []renamer{
-		{From: "hostname", To: "host"},
+	r := Rename{
+		Replaces: []Replace{
+			{Tag: "hostname", Dest: "host"},
+		},
 	}
 	m := newMetric("foo", map[string]string{"hostname": "localhost", "region": "east-1"}, nil)
 	results := r.Apply(m)
@@ -47,9 +49,10 @@ func TestTagRename(t *testing.T) {
 }
 
 func TestFieldRename(t *testing.T) {
-	r := Rename{}
-	r.Field = []renamer{
-		{From: "time_msec", To: "time"},
+	r := Rename{
+		Replaces: []Replace{
+			{Field: "time_msec", Dest: "time"},
+		},
 	}
 	m := newMetric("foo", nil, map[string]interface{}{"time_msec": int64(1250), "snakes": true})
 	results := r.Apply(m)