add parse_multivalue config to collectd parser

docs/DATA_FORMATS_INPUT.md

@@ -479,6 +479,12 @@ You can also change the path to the typesdb or add additional typesdb using
   collectd_security_level = "encrypt"
   ## Path of to TypesDB specifications
   collectd_typesdb = ["/usr/share/collectd/types.db"]
+
+  # Multi-value plugins can be handled two ways.  
+  # "split" will parse and store the multi-value plugin data into separate measurements
+  # "join" will parse and store the multi-value plugin as a single multi-value measurement.  
+  # "split" is the default behavior for backward compatability with previous versions of influxdb.
+  collectd_parse_multivalue = "split"
 ```
 
 # Dropwizard:

internal/config/config.go

@@ -1285,6 +1285,14 @@ func buildParser(name string, tbl *ast.Table) (parsers.Parser, error) {
 		}
 	}
 
+	if node, ok := tbl.Fields["collectd_parse_multivalue"]; ok {
+		if kv, ok := node.(*ast.KeyValue); ok {
+			if str, ok := kv.Value.(*ast.String); ok {
+				c.CollectdSplit = str.Value
+			}
+		}
+	}
+
 	if node, ok := tbl.Fields["collectd_typesdb"]; ok {
 		if kv, ok := node.(*ast.KeyValue); ok {
 			if ary, ok := kv.Value.(*ast.Array); ok {
@@ -1348,6 +1356,7 @@ func buildParser(name string, tbl *ast.Table) (parsers.Parser, error) {
 	delete(tbl.Fields, "collectd_auth_file")
 	delete(tbl.Fields, "collectd_security_level")
 	delete(tbl.Fields, "collectd_typesdb")
+	delete(tbl.Fields, "collectd_parse_multivalue")
 	delete(tbl.Fields, "dropwizard_metric_registry_path")
 	delete(tbl.Fields, "dropwizard_time_path")
 	delete(tbl.Fields, "dropwizard_time_format")

plugins/parsers/collectd/parser.go

@@ -21,7 +21,10 @@ type CollectdParser struct {
 	// DefaultTags will be added to every parsed metric
 	DefaultTags map[string]string
 
-	popts network.ParseOpts
+	//whether or not to split multi value metric into multiple metrics
+	//default value is split
+	ParseMultiValue string
+	popts           network.ParseOpts
 }
 
 func (p *CollectdParser) SetParseOpts(popts *network.ParseOpts) {
@@ -32,6 +35,7 @@ func NewCollectdParser(
 	authFile string,
 	securityLevel string,
 	typesDB []string,
+	split string,
 ) (*CollectdParser, error) {
 	popts := network.ParseOpts{}
 
@@ -64,7 +68,8 @@ func NewCollectdParser(
 		}
 	}
 
-	parser := CollectdParser{popts: popts}
+	parser := CollectdParser{popts: popts,
+		ParseMultiValue: split}
 	return &parser, nil
 }
 
@@ -76,7 +81,7 @@ func (p *CollectdParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 
 	metrics := []telegraf.Metric{}
 	for _, valueList := range valueLists {
-		metrics = append(metrics, UnmarshalValueList(valueList)...)
+		metrics = append(metrics, UnmarshalValueList(valueList, p.ParseMultiValue)...)
 	}
 
 	if len(p.DefaultTags) > 0 {
@@ -111,47 +116,91 @@ func (p *CollectdParser) SetDefaultTags(tags map[string]string) {
 }
 
 // UnmarshalValueList translates a ValueList into a Telegraf metric.
-func UnmarshalValueList(vl *api.ValueList) []telegraf.Metric {
+func UnmarshalValueList(vl *api.ValueList, multiValue string) []telegraf.Metric {
 	timestamp := vl.Time.UTC()
 
 	var metrics []telegraf.Metric
-	for i := range vl.Values {
-		var name string
-		name = fmt.Sprintf("%s_%s", vl.Identifier.Plugin, vl.DSName(i))
-		tags := make(map[string]string)
-		fields := make(map[string]interface{})
 
-		// Convert interface back to actual type, then to float64
-		switch value := vl.Values[i].(type) {
-		case api.Gauge:
-			fields["value"] = float64(value)
-		case api.Derive:
-			fields["value"] = float64(value)
-		case api.Counter:
-			fields["value"] = float64(value)
-		}
+	//set multiValue to default "split" if nothing is specified
+	if multiValue == "" {
+		multiValue = "split"
+	}
+	switch multiValue {
+	case "split":
+		for i := range vl.Values {
+			var name string
+			name = fmt.Sprintf("%s_%s", vl.Identifier.Plugin, vl.DSName(i))
+			tags := make(map[string]string)
+			fields := make(map[string]interface{})
+
+			// Convert interface back to actual type, then to float64
+			switch value := vl.Values[i].(type) {
+			case api.Gauge:
+				fields["value"] = float64(value)
+			case api.Derive:
+				fields["value"] = float64(value)
+			case api.Counter:
+				fields["value"] = float64(value)
+			}
 
-		if vl.Identifier.Host != "" {
-			tags["host"] = vl.Identifier.Host
-		}
-		if vl.Identifier.PluginInstance != "" {
-			tags["instance"] = vl.Identifier.PluginInstance
-		}
-		if vl.Identifier.Type != "" {
-			tags["type"] = vl.Identifier.Type
+			if vl.Identifier.Host != "" {
+				tags["host"] = vl.Identifier.Host
+			}
+			if vl.Identifier.PluginInstance != "" {
+				tags["instance"] = vl.Identifier.PluginInstance
+			}
+			if vl.Identifier.Type != "" {
+				tags["type"] = vl.Identifier.Type
+			}
+			if vl.Identifier.TypeInstance != "" {
+				tags["type_instance"] = vl.Identifier.TypeInstance
+			}
+
+			// Drop invalid points
+			m, err := metric.New(name, tags, fields, timestamp)
+			if err != nil {
+				log.Printf("E! Dropping metric %v: %v", name, err)
+				continue
+			}
+
+			metrics = append(metrics, m)
 		}
-		if vl.Identifier.TypeInstance != "" {
-			tags["type_instance"] = vl.Identifier.TypeInstance
+	case "join":
+		name := vl.Identifier.Plugin
+		tags := make(map[string]string)
+		fields := make(map[string]interface{})
+		for i := range vl.Values {
+			switch value := vl.Values[i].(type) {
+			case api.Gauge:
+				fields[vl.DSName(i)] = float64(value)
+			case api.Derive:
+				fields[vl.DSName(i)] = float64(value)
+			case api.Counter:
+				fields[vl.DSName(i)] = float64(value)
+			}
+
+			if vl.Identifier.Host != "" {
+				tags["host"] = vl.Identifier.Host
+			}
+			if vl.Identifier.PluginInstance != "" {
+				tags["instance"] = vl.Identifier.PluginInstance
+			}
+			if vl.Identifier.Type != "" {
+				tags["type"] = vl.Identifier.Type
+			}
+			if vl.Identifier.TypeInstance != "" {
+				tags["type_instance"] = vl.Identifier.TypeInstance
+			}
 		}
 
-		// Drop invalid points
 		m, err := metric.New(name, tags, fields, timestamp)
 		if err != nil {
 			log.Printf("E! Dropping metric %v: %v", name, err)
-			continue
 		}
 
 		metrics = append(metrics, m)
+	default:
+		log.Printf("parse-multi-value config can only be 'split' or 'join'")
 	}
 	return metrics
 }

plugins/parsers/collectd/parser_test.go

@@ -6,6 +6,7 @@ import (
 
 	"collectd.org/api"
 	"collectd.org/network"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/influxdata/telegraf"
@@ -76,7 +77,7 @@ var multiMetric = testCase{
 				api.Derive(42),
 				api.Gauge(42),
 			},
-			DSNames: []string(nil),
+			DSNames: []string{"t1", "t2"},
 		},
 	},
 	[]metricData{
@@ -108,7 +109,7 @@ var multiMetric = testCase{
 }
 
 func TestNewCollectdParser(t *testing.T) {
-	parser, err := NewCollectdParser("", "", []string{})
+	parser, err := NewCollectdParser("", "", []string{}, "join")
 	require.Nil(t, err)
 	require.Equal(t, parser.popts.SecurityLevel, network.None)
 	require.NotNil(t, parser.popts.PasswordLookup)
@@ -133,6 +134,19 @@ func TestParse(t *testing.T) {
 	}
 }
 
+func TestParseMultiValueSplit(t *testing.T) {
+	buf, err := writeValueList(multiMetric.vl)
+	require.Nil(t, err)
+	bytes, err := buf.Bytes()
+	require.Nil(t, err)
+
+	parser := &CollectdParser{ParseMultiValue: "split"}
+	metrics, err := parser.Parse(bytes)
+	require.Nil(t, err)
+
+	assert.Equal(t, 2, len(metrics))
+}
+
 func TestParse_DefaultTags(t *testing.T) {
 	buf, err := writeValueList(singleMetric.vl)
 	require.Nil(t, err)
@@ -266,7 +280,7 @@ func TestParseLine(t *testing.T) {
 	bytes, err := buf.Bytes()
 	require.Nil(t, err)
 
-	parser, err := NewCollectdParser("", "", []string{})
+	parser, err := NewCollectdParser("", "", []string{}, "split")
 	require.Nil(t, err)
 	metric, err := parser.ParseLine(string(bytes))
 	require.Nil(t, err)

plugins/parsers/registry.go

@@ -66,6 +66,9 @@ type Config struct {
 	// Dataset specification for collectd
 	CollectdTypesDB []string
 
+	// whether to split or join multivalue metrics
+	CollectdSplit string
+
 	// DataType only applies to value, this will be the type to parse value to
 	DataType string
 
@@ -109,7 +112,7 @@ func NewParser(config *Config) (Parser, error) {
 			config.Templates, config.DefaultTags)
 	case "collectd":
 		parser, err = NewCollectdParser(config.CollectdAuthFile,
-			config.CollectdSecurityLevel, config.CollectdTypesDB)
+			config.CollectdSecurityLevel, config.CollectdTypesDB, config.CollectdSplit)
 	case "dropwizard":
 		parser, err = NewDropwizardParser(
 			config.DropwizardMetricRegistryPath,
@@ -172,8 +175,9 @@ func NewCollectdParser(
 	authFile string,
 	securityLevel string,
 	typesDB []string,
+	split string,
 ) (Parser, error) {
-	return collectd.NewCollectdParser(authFile, securityLevel, typesDB)
+	return collectd.NewCollectdParser(authFile, securityLevel, typesDB, split)
 }
 
 func NewDropwizardParser(