feat(parsers/logfmt): Add tag support (#11060)

plugins/parsers/logfmt/README.md

@@ -15,6 +15,9 @@ The `logfmt` data format parses data in [logfmt] format.
   ## more about them here:
   ##   https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
   data_format = "logfmt"
+
+  ## Array of key names which should be collected as tags. Globs accepted.
+  logfmt_tag_keys = ["method","host"]
 ```
 
 ## Metrics
@@ -26,5 +29,5 @@ of the field is automatically determined based on the contents of the value.
 
 ```text
 - method=GET host=example.org ts=2018-07-24T19:43:40.275Z connect=4ms service=8ms status=200 bytes=1653
-+ logfmt method="GET",host="example.org",ts="2018-07-24T19:43:40.275Z",connect="4ms",service="8ms",status=200i,bytes=1653i
++ logfmt,host=example.org,method=GET ts="2018-07-24T19:43:40.275Z",connect="4ms",service="8ms",status=200i,bytes=1653i
 ```

plugins/parsers/logfmt/parser.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/go-logfmt/logfmt"
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/filter"
 	"github.com/influxdata/telegraf/metric"
 )
 
@@ -17,17 +18,22 @@ var (
 
 // Parser decodes logfmt formatted messages into metrics.
 type Parser struct {
+	TagKeys []string `toml:"logfmt_tag_keys"`
+
 	MetricName  string
 	DefaultTags map[string]string
 	Now         func() time.Time
+
+	tagFilter filter.Filter
 }
 
 // NewParser creates a parser.
-func NewParser(metricName string, defaultTags map[string]string) *Parser {
+func NewParser(metricName string, defaultTags map[string]string, tagKeys []string) *Parser {
 	return &Parser{
 		MetricName:  metricName,
 		DefaultTags: defaultTags,
 		Now:         time.Now,
+		TagKeys:     tagKeys,
 	}
 }
 
@@ -46,14 +52,17 @@ func (p *Parser) Parse(b []byte) ([]telegraf.Metric, error) {
 			break
 		}
 		fields := make(map[string]interface{})
+		tags := make(map[string]string)
 		for decoder.ScanKeyval() {
 			if string(decoder.Value()) == "" {
 				continue
 			}
 
 			//type conversions
 			value := string(decoder.Value())
-			if iValue, err := strconv.ParseInt(value, 10, 64); err == nil {
+			if p.tagFilter != nil && p.tagFilter.Match(string(decoder.Key())) {
+				tags[string(decoder.Key())] = value
+			} else if iValue, err := strconv.ParseInt(value, 10, 64); err == nil {
 				fields[string(decoder.Key())] = iValue
 			} else if fValue, err := strconv.ParseFloat(value, 64); err == nil {
 				fields[string(decoder.Key())] = fValue
@@ -63,11 +72,11 @@ func (p *Parser) Parse(b []byte) ([]telegraf.Metric, error) {
 				fields[string(decoder.Key())] = value
 			}
 		}
-		if len(fields) == 0 {
+		if len(fields) == 0 && len(tags) == 0 {
 			continue
 		}
 
-		m := metric.New(p.MetricName, map[string]string{}, fields, p.Now())
+		m := metric.New(p.MetricName, tags, fields, p.Now())
 
 		metrics = append(metrics, m)
 	}
@@ -106,3 +115,14 @@ func (p *Parser) applyDefaultTags(metrics []telegraf.Metric) {
 		}
 	}
 }
+
+func (p *Parser) Init() error {
+	var err error
+
+	// Compile tag key patterns
+	if p.tagFilter, err = filter.Compile(p.TagKeys); err != nil {
+		return fmt.Errorf("error compiling tag pattern: %w", err)
+	}
+
+	return nil
+}

plugins/parsers/logfmt/parser_test.go

@@ -5,17 +5,10 @@ import (
 	"time"
 
 	"github.com/influxdata/telegraf"
-	"github.com/influxdata/telegraf/metric"
 	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
 )
 
-func MustMetric(t *testing.T, m *testutil.Metric) telegraf.Metric {
-	t.Helper()
-	v := metric.New(m.Measurement, m.Tags, m.Fields, m.Time)
-
-	return v
-}
-
 func TestParse(t *testing.T) {
 	tests := []struct {
 		name        string
@@ -222,3 +215,79 @@ func TestParseLine(t *testing.T) {
 		})
 	}
 }
+
+func TestTags(t *testing.T) {
+	tests := []struct {
+		name        string
+		measurement string
+		tagKeys     []string
+		s           string
+		want        telegraf.Metric
+		wantErr     bool
+	}{
+		{
+			name:        "logfmt parser returns tags and fields",
+			measurement: "testlog",
+			tagKeys:     []string{"lvl"},
+			s:           "ts=2018-07-24T19:43:40.275Z lvl=info msg=\"http request\" method=POST",
+			want: testutil.MustMetric(
+				"testlog",
+				map[string]string{
+					"lvl": "info",
+				},
+				map[string]interface{}{
+					"msg":    "http request",
+					"method": "POST",
+					"ts":     "2018-07-24T19:43:40.275Z",
+				},
+				time.Unix(0, 0),
+			),
+		},
+		{
+			name:        "logfmt parser returns no empty metrics",
+			measurement: "testlog",
+			tagKeys:     []string{"lvl"},
+			s:           "lvl=info",
+			want: testutil.MustMetric(
+				"testlog",
+				map[string]string{
+					"lvl": "info",
+				},
+				map[string]interface{}{},
+				time.Unix(0, 0),
+			),
+		},
+		{
+			name:        "logfmt parser returns all keys as tag",
+			measurement: "testlog",
+			tagKeys:     []string{"*"},
+			s:           "ts=2018-07-24T19:43:40.275Z lvl=info msg=\"http request\" method=POST",
+			want: testutil.MustMetric(
+				"testlog",
+				map[string]string{
+					"lvl":    "info",
+					"msg":    "http request",
+					"method": "POST",
+					"ts":     "2018-07-24T19:43:40.275Z",
+				},
+				map[string]interface{}{},
+				time.Unix(0, 0),
+			),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			l := NewParser(tt.measurement, map[string]string{}, tt.tagKeys)
+			assert.NoError(t, l.Init())
+
+			got, err := l.ParseLine(tt.s)
+
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+			testutil.RequireMetricEqual(t, tt.want, got, testutil.IgnoreTime())
+		})
+	}
+}

plugins/parsers/registry.go

@@ -195,6 +195,9 @@ type Config struct {
 
 	// Influx configuration
 	InfluxParserType string `toml:"influx_parser_type"`
+
+	// LogFmt configuration
+	LogFmtTagKeys []string `toml:"logfmt_tag_keys"`
 }
 
 type XPathConfig xpath.Config
@@ -262,7 +265,7 @@ func NewParser(config *Config) (Parser, error) {
 			config.GrokTimezone,
 			config.GrokUniqueTimestamp)
 	case "logfmt":
-		parser, err = NewLogFmtParser(config.MetricName, config.DefaultTags)
+		parser, err = NewLogFmtParser(config.MetricName, config.DefaultTags, config.LogFmtTagKeys)
 	case "form_urlencoded":
 		parser, err = NewFormUrlencodedParser(
 			config.MetricName,
@@ -389,8 +392,10 @@ func NewDropwizardParser(
 }
 
 // NewLogFmtParser returns a logfmt parser with the default options.
-func NewLogFmtParser(metricName string, defaultTags map[string]string) (Parser, error) {
-	return logfmt.NewParser(metricName, defaultTags), nil
+func NewLogFmtParser(metricName string, defaultTags map[string]string, tagKeys []string) (Parser, error) {
+	parser := logfmt.NewParser(metricName, defaultTags, tagKeys)
+	err := parser.Init()
+	return parser, err
 }
 
 func NewWavefrontParser(defaultTags map[string]string) (Parser, error) {