Introduce a dedicated parser for prometheus

docs/DATA_FORMATS_INPUT.md

@@ -16,6 +16,7 @@ Protocol or in JSON format.
 - [Nagios](/plugins/parsers/nagios)
 - [Value](/plugins/parsers/value), ie: 45 or "booyah"
 - [Wavefront](/plugins/parsers/wavefront)
+- [Prometheus](/plugins/parsers/prometheus)
 
 Any input plugin containing the `data_format` option can use it to select the
 desired parser:

plugins/inputs/prometheus/parser.go

@@ -1,8 +1,5 @@
 package prometheus
 
-// Parser inspired from
-// https://github.com/prometheus/prom2json/blob/master/main.go
-
 import (
 	"bufio"
 	"bytes"
@@ -15,169 +12,27 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/metric"
+	. "github.com/influxdata/telegraf/plugins/parsers/prometheus/common"
+
 	"github.com/matttproud/golang_protobuf_extensions/pbutil"
 	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 )
 
-// Parse returns a slice of Metrics from a text representation of a
-// metrics
-func ParseV2(buf []byte, header http.Header) ([]telegraf.Metric, error) {
-	var metrics []telegraf.Metric
-	var parser expfmt.TextParser
-	// parse even if the buffer begins with a newline
-	buf = bytes.TrimPrefix(buf, []byte("\n"))
-	// Read raw data
-	buffer := bytes.NewBuffer(buf)
-	reader := bufio.NewReader(buffer)
-
-	mediatype, params, err := mime.ParseMediaType(header.Get("Content-Type"))
-	// Prepare output
-	metricFamilies := make(map[string]*dto.MetricFamily)
-
-	if err == nil && mediatype == "application/vnd.google.protobuf" &&
-		params["encoding"] == "delimited" &&
-		params["proto"] == "io.prometheus.client.MetricFamily" {
-		for {
-			mf := &dto.MetricFamily{}
-			if _, ierr := pbutil.ReadDelimited(reader, mf); ierr != nil {
-				if ierr == io.EOF {
-					break
-				}
-				return nil, fmt.Errorf("reading metric family protocol buffer failed: %s", ierr)
-			}
-			metricFamilies[mf.GetName()] = mf
-		}
-	} else {
-		metricFamilies, err = parser.TextToMetricFamilies(reader)
-		if err != nil {
-			return nil, fmt.Errorf("reading text format failed: %s", err)
-		}
-	}
-
-	// make sure all metrics have a consistent timestamp so that metrics don't straddle two different seconds
-	now := time.Now()
-	// read metrics
-	for metricName, mf := range metricFamilies {
-		for _, m := range mf.Metric {
-			// reading tags
-			tags := makeLabels(m)
-
-			if mf.GetType() == dto.MetricType_SUMMARY {
-				// summary metric
-				telegrafMetrics := makeQuantilesV2(m, tags, metricName, mf.GetType(), now)
-				metrics = append(metrics, telegrafMetrics...)
-			} else if mf.GetType() == dto.MetricType_HISTOGRAM {
-				// histogram metric
-				telegrafMetrics := makeBucketsV2(m, tags, metricName, mf.GetType(), now)
-				metrics = append(metrics, telegrafMetrics...)
-			} else {
-				// standard metric
-				// reading fields
-				fields := make(map[string]interface{})
-				fields = getNameAndValueV2(m, metricName)
-				// converting to telegraf metric
-				if len(fields) > 0 {
-					var t time.Time
-					if m.TimestampMs != nil && *m.TimestampMs > 0 {
-						t = time.Unix(0, *m.TimestampMs*1000000)
-					} else {
-						t = now
-					}
-					metric, err := metric.New("prometheus", tags, fields, t, valueType(mf.GetType()))
-					if err == nil {
-						metrics = append(metrics, metric)
-					}
-				}
-			}
-		}
-	}
-
-	return metrics, err
-}
-
-// Get Quantiles for summary metric & Buckets for histogram
-func makeQuantilesV2(m *dto.Metric, tags map[string]string, metricName string, metricType dto.MetricType, now time.Time) []telegraf.Metric {
-	var metrics []telegraf.Metric
-	fields := make(map[string]interface{})
-	var t time.Time
-	if m.TimestampMs != nil && *m.TimestampMs > 0 {
-		t = time.Unix(0, *m.TimestampMs*1000000)
-	} else {
-		t = now
-	}
-	fields[metricName+"_count"] = float64(m.GetSummary().GetSampleCount())
-	fields[metricName+"_sum"] = float64(m.GetSummary().GetSampleSum())
-	met, err := metric.New("prometheus", tags, fields, t, valueType(metricType))
-	if err == nil {
-		metrics = append(metrics, met)
-	}
-
-	for _, q := range m.GetSummary().Quantile {
-		newTags := tags
-		fields = make(map[string]interface{})
-
-		newTags["quantile"] = fmt.Sprint(q.GetQuantile())
-		fields[metricName] = float64(q.GetValue())
-
-		quantileMetric, err := metric.New("prometheus", newTags, fields, t, valueType(metricType))
-		if err == nil {
-			metrics = append(metrics, quantileMetric)
-		}
-	}
-	return metrics
-}
-
-// Get Buckets  from histogram metric
-func makeBucketsV2(m *dto.Metric, tags map[string]string, metricName string, metricType dto.MetricType, now time.Time) []telegraf.Metric {
-	var metrics []telegraf.Metric
-	fields := make(map[string]interface{})
-	var t time.Time
-	if m.TimestampMs != nil && *m.TimestampMs > 0 {
-		t = time.Unix(0, *m.TimestampMs*1000000)
-	} else {
-		t = now
-	}
-	fields[metricName+"_count"] = float64(m.GetHistogram().GetSampleCount())
-	fields[metricName+"_sum"] = float64(m.GetHistogram().GetSampleSum())
-
-	met, err := metric.New("prometheus", tags, fields, t, valueType(metricType))
-	if err == nil {
-		metrics = append(metrics, met)
-	}
-
-	for _, b := range m.GetHistogram().Bucket {
-		newTags := tags
-		fields = make(map[string]interface{})
-		newTags["le"] = fmt.Sprint(b.GetUpperBound())
-		fields[metricName+"_bucket"] = float64(b.GetCumulativeCount())
-
-		histogramMetric, err := metric.New("prometheus", newTags, fields, t, valueType(metricType))
-		if err == nil {
-			metrics = append(metrics, histogramMetric)
-		}
-	}
-	return metrics
-}
-
-// Parse returns a slice of Metrics from a text representation of a
-// metrics
 func Parse(buf []byte, header http.Header) ([]telegraf.Metric, error) {
-	var metrics []telegraf.Metric
 	var parser expfmt.TextParser
+	var metrics []telegraf.Metric
+	var err error
 	// parse even if the buffer begins with a newline
 	buf = bytes.TrimPrefix(buf, []byte("\n"))
 	// Read raw data
 	buffer := bytes.NewBuffer(buf)
 	reader := bufio.NewReader(buffer)
 
-	mediatype, params, err := mime.ParseMediaType(header.Get("Content-Type"))
 	// Prepare output
 	metricFamilies := make(map[string]*dto.MetricFamily)
 
-	if err == nil && mediatype == "application/vnd.google.protobuf" &&
-		params["encoding"] == "delimited" &&
-		params["proto"] == "io.prometheus.client.MetricFamily" {
+	if isProtobuf(header) {
 		for {
 			mf := &dto.MetricFamily{}
 			if _, ierr := pbutil.ReadDelimited(reader, mf); ierr != nil {
@@ -195,13 +50,13 @@ func Parse(buf []byte, header http.Header) ([]telegraf.Metric, error) {
 		}
 	}
 
-	// make sure all metrics have a consistent timestamp so that metrics don't straddle two different seconds
 	now := time.Now()
 	// read metrics
 	for metricName, mf := range metricFamilies {
 		for _, m := range mf.Metric {
 			// reading tags
-			tags := makeLabels(m)
+			tags := MakeLabels(m, nil)
+
 			// reading fields
 			fields := make(map[string]interface{})
 			if mf.GetType() == dto.MetricType_SUMMARY {
@@ -227,7 +82,7 @@ func Parse(buf []byte, header http.Header) ([]telegraf.Metric, error) {
 				} else {
 					t = now
 				}
-				metric, err := metric.New(metricName, tags, fields, t, valueType(mf.GetType()))
+				metric, err := metric.New(metricName, tags, fields, t, ValueType(mf.GetType()))
 				if err == nil {
 					metrics = append(metrics, metric)
 				}
@@ -238,19 +93,16 @@ func Parse(buf []byte, header http.Header) ([]telegraf.Metric, error) {
 	return metrics, err
 }
 
-func valueType(mt dto.MetricType) telegraf.ValueType {
-	switch mt {
-	case dto.MetricType_COUNTER:
-		return telegraf.Counter
-	case dto.MetricType_GAUGE:
-		return telegraf.Gauge
-	case dto.MetricType_SUMMARY:
-		return telegraf.Summary
-	case dto.MetricType_HISTOGRAM:
-		return telegraf.Histogram
-	default:
-		return telegraf.Untyped
+func isProtobuf(header http.Header) bool {
+	mediatype, params, error := mime.ParseMediaType(header.Get("Content-Type"))
+
+	if error != nil {
+		return false
 	}
+
+	return mediatype == "application/vnd.google.protobuf" &&
+		params["encoding"] == "delimited" &&
+		params["proto"] == "io.prometheus.client.MetricFamily"
 }
 
 // Get Quantiles from summary metric
@@ -273,15 +125,6 @@ func makeBuckets(m *dto.Metric) map[string]interface{} {
 	return fields
 }
 
-// Get labels from metric
-func makeLabels(m *dto.Metric) map[string]string {
-	result := map[string]string{}
-	for _, lp := range m.Label {
-		result[lp.GetName()] = lp.GetValue()
-	}
-	return result
-}
-
 // Get name and value from metric
 func getNameAndValue(m *dto.Metric) map[string]interface{} {
 	fields := make(map[string]interface{})
@@ -300,22 +143,3 @@ func getNameAndValue(m *dto.Metric) map[string]interface{} {
 	}
 	return fields
 }
-
-// Get name and value from metric
-func getNameAndValueV2(m *dto.Metric, metricName string) map[string]interface{} {
-	fields := make(map[string]interface{})
-	if m.Gauge != nil {
-		if !math.IsNaN(m.GetGauge().GetValue()) {
-			fields[metricName] = float64(m.GetGauge().GetValue())
-		}
-	} else if m.Counter != nil {
-		if !math.IsNaN(m.GetCounter().GetValue()) {
-			fields[metricName] = float64(m.GetCounter().GetValue())
-		}
-	} else if m.Untyped != nil {
-		if !math.IsNaN(m.GetUntyped().GetValue()) {
-			fields[metricName] = float64(m.GetUntyped().GetValue())
-		}
-	}
-	return fields
-}

plugins/inputs/prometheus/prometheus.go

@@ -15,6 +15,7 @@ import (
 	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/plugins/common/tls"
 	"github.com/influxdata/telegraf/plugins/inputs"
+	parser_v2 "github.com/influxdata/telegraf/plugins/parsers/prometheus"
 )
 
 const acceptHeader = `application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.7,text/plain;version=0.0.4;q=0.3,*/*;q=0.1`
@@ -322,7 +323,8 @@ func (p *Prometheus) gatherURL(u URLAndAddress, acc telegraf.Accumulator) error
 	}
 
 	if p.MetricVersion == 2 {
-		metrics, err = ParseV2(body, resp.Header)
+		parser := parser_v2.Parser{}
+		metrics, err = parser.Parse(body)
 	} else {
 		metrics, err = Parse(body, resp.Header)
 	}

plugins/parsers/prometheus/README.md

@@ -0,0 +1,17 @@
+# Prometheus Text-Based Format
+
+There are no additional configuration options for [Prometheus Text-Based Format][]. The metrics are parsed directly into Telegraf metrics. It is used internally in [prometheus input](/plugins/inputs/prometheus) or can be used in [http_listener_v2](/plugins/inputs/http_listener_v2) to simulate Pushgateway
+
+[Prometheus Text-Based Format]: https://prometheus.io/docs/instrumenting/exposition_formats/#text-based-format
+
+```toml
+[[inputs.file]]
+  files = ["example"]
+
+  ## Data format to consume.
+  ## Each data format has its own unique set of configuration options, read
+  ## more about them here:
+  ##   https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
+  data_format = "prometheus"
+
+```

plugins/parsers/prometheus/common/helpers.go

@@ -0,0 +1,39 @@
+package common
+
+import (
+	"github.com/influxdata/telegraf"
+	dto "github.com/prometheus/client_model/go"
+)
+
+func ValueType(mt dto.MetricType) telegraf.ValueType {
+	switch mt {
+	case dto.MetricType_COUNTER:
+		return telegraf.Counter
+	case dto.MetricType_GAUGE:
+		return telegraf.Gauge
+	case dto.MetricType_SUMMARY:
+		return telegraf.Summary
+	case dto.MetricType_HISTOGRAM:
+		return telegraf.Histogram
+	default:
+		return telegraf.Untyped
+	}
+}
+
+// Get labels from metric
+func MakeLabels(m *dto.Metric, defaultTags map[string]string) map[string]string {
+	result := map[string]string{}
+	for _, lp := range m.Label {
+		result[lp.GetName()] = lp.GetValue()
+	}
+
+	if defaultTags != nil {
+		for k, v := range defaultTags {
+			if _, exists := result[k]; exists {
+				result[k] = v
+			}
+		}
+	}
+
+	return result
+}