Prometheus parser fix, parse headers properly

closes #1458

plugins/inputs/prometheus/parser.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"math"
 	"mime"
+	"net/http"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -19,17 +20,9 @@ import (
 	"github.com/prometheus/common/expfmt"
 )
 
-// PrometheusParser is an object for Parsing incoming metrics.
-type PrometheusParser struct {
-	// PromFormat
-	PromFormat map[string]string
-	// DefaultTags will be added to every parsed metric
-	//	DefaultTags map[string]string
-}
-
 // Parse returns a slice of Metrics from a text representation of a
 // metrics
-func (p *PrometheusParser) Parse(buf []byte) ([]telegraf.Metric, error) {
+func Parse(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
@@ -38,97 +31,71 @@ func (p *PrometheusParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 	buffer := bytes.NewBuffer(buf)
 	reader := bufio.NewReader(buffer)
 
-	// Get format
-	mediatype, params, err := mime.ParseMediaType(p.PromFormat["Content-Type"])
+	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 {
-			metricFamily := &dto.MetricFamily{}
-			if _, err = pbutil.ReadDelimited(reader, metricFamily); err != nil {
-				if err == io.EOF {
+			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", err)
+				return nil, fmt.Errorf("reading metric family protocol buffer failed: %s", ierr)
 			}
-			metricFamilies[metricFamily.GetName()] = metricFamily
+			metricFamilies[mf.GetName()] = mf
 		}
 	} else {
 		metricFamilies, err = parser.TextToMetricFamilies(reader)
 		if err != nil {
 			return nil, fmt.Errorf("reading text format failed: %s", err)
 		}
-		// read metrics
-		for metricName, mf := range metricFamilies {
-			for _, m := range mf.Metric {
-				// reading tags
-				tags := makeLabels(m)
-				/*
-					for key, value := range p.DefaultTags {
-						tags[key] = value
-					}
-				*/
-				// reading fields
-				fields := make(map[string]interface{})
-				if mf.GetType() == dto.MetricType_SUMMARY {
-					// summary metric
-					fields = makeQuantiles(m)
-					fields["count"] = float64(m.GetSummary().GetSampleCount())
-					fields["sum"] = float64(m.GetSummary().GetSampleSum())
-				} else if mf.GetType() == dto.MetricType_HISTOGRAM {
-					// historgram metric
-					fields = makeBuckets(m)
-					fields["count"] = float64(m.GetHistogram().GetSampleCount())
-					fields["sum"] = float64(m.GetHistogram().GetSampleSum())
+	}
 
+	// read metrics
+	for metricName, mf := range metricFamilies {
+		for _, m := range mf.Metric {
+			// reading tags
+			tags := makeLabels(m)
+			// reading fields
+			fields := make(map[string]interface{})
+			if mf.GetType() == dto.MetricType_SUMMARY {
+				// summary metric
+				fields = makeQuantiles(m)
+				fields["count"] = float64(m.GetSummary().GetSampleCount())
+				fields["sum"] = float64(m.GetSummary().GetSampleSum())
+			} else if mf.GetType() == dto.MetricType_HISTOGRAM {
+				// historgram metric
+				fields = makeBuckets(m)
+				fields["count"] = float64(m.GetHistogram().GetSampleCount())
+				fields["sum"] = float64(m.GetHistogram().GetSampleSum())
+
+			} else {
+				// standard metric
+				fields = getNameAndValue(m)
+			}
+			// 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 {
-					// standard metric
-					fields = getNameAndValue(m)
+					t = time.Now()
 				}
-				// 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 = time.Now()
-					}
-					metric, err := telegraf.NewMetric(metricName, tags, fields, t)
-					if err == nil {
-						metrics = append(metrics, metric)
-					}
+				metric, err := telegraf.NewMetric(metricName, tags, fields, t)
+				if err == nil {
+					metrics = append(metrics, metric)
 				}
 			}
 		}
 	}
+
 	return metrics, err
 }
 
-// Parse one line
-func (p *PrometheusParser) ParseLine(line string) (telegraf.Metric, error) {
-	metrics, err := p.Parse([]byte(line + "\n"))
-
-	if err != nil {
-		return nil, err
-	}
-
-	if len(metrics) < 1 {
-		return nil, fmt.Errorf(
-			"Can not parse the line: %s, for data format: prometheus", line)
-	}
-
-	return metrics[0], nil
-}
-
-/*
-// Set default tags
-func (p *PrometheusParser) SetDefaultTags(tags map[string]string) {
-	p.DefaultTags = tags
-}
-*/
-
 // Get Quantiles from summary metric
 func makeQuantiles(m *dto.Metric) map[string]interface{} {
 	fields := make(map[string]interface{})