Add Prometheus Remote Write Exporter supporting Cortex - helper (#1555)

* add helper for Prometheus remote write exporter

* remove copyright year

* test coverage 100%

* test coverage 100%

exporter/prometheusremotewriteexporter/config.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

exporter/prometheusremotewriteexporter/config_test.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

exporter/prometheusremotewriteexporter/exporter.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

exporter/prometheusremotewriteexporter/exporter_test.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

exporter/prometheusremotewriteexporter/factory.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -66,11 +66,7 @@ func createMetricsExporter(_ context.Context, _ component.ExporterCreateParams,
 		exporterhelper.WithShutdown(prwe.shutdown),
 	)
 
-	if err != nil {
-		return nil, err
-	}
-
-	return prwexp, nil
+	return prwexp, err
 }
 
 func createDefaultConfig() configmodels.Exporter {

exporter/prometheusremotewriteexporter/factory_test.go

@@ -1,4 +1,4 @@
-// Copyright 2020 The OpenTelemetry Authors
+// Copyright The OpenTelemetry Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

exporter/prometheusremotewriteexporter/helper.go

@@ -0,0 +1,210 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheusremotewriteexporter
+
+import (
+	"log"
+	"sort"
+	"strings"
+	"unicode"
+
+	"github.com/prometheus/prometheus/prompb"
+
+	common "go.opentelemetry.io/collector/internal/data/opentelemetry-proto-gen/common/v1"
+	otlp "go.opentelemetry.io/collector/internal/data/opentelemetry-proto-gen/metrics/v1"
+)
+
+const (
+	totalStr  = "total"
+	delimeter = "_"
+	keyStr    = "key"
+)
+
+// ByLabelName enables the usage of sort.Sort() with a slice of labels
+type ByLabelName []prompb.Label
+
+func (a ByLabelName) Len() int           { return len(a) }
+func (a ByLabelName) Less(i, j int) bool { return a[i].Name < a[j].Name }
+func (a ByLabelName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// validateMetrics returns a bool representing whether the metric has a valid type and temporality combination.
+func validateMetrics(desc *otlp.MetricDescriptor) bool {
+
+	if desc == nil {
+		return false
+	}
+
+	switch desc.GetType() {
+	case otlp.MetricDescriptor_MONOTONIC_DOUBLE, otlp.MetricDescriptor_MONOTONIC_INT64,
+		otlp.MetricDescriptor_HISTOGRAM, otlp.MetricDescriptor_SUMMARY:
+		return desc.GetTemporality() == otlp.MetricDescriptor_CUMULATIVE
+	case otlp.MetricDescriptor_INT64, otlp.MetricDescriptor_DOUBLE:
+		return true
+	}
+
+	return false
+}
+
+// addSample finds a TimeSeries in tsMap that corresponds to the label set labels, and add sample to the TimeSeries; it
+// creates a new TimeSeries in the map if not found. tsMap is unmodified if either of its parameters is nil.
+func addSample(tsMap map[string]*prompb.TimeSeries, sample *prompb.Sample, labels []prompb.Label,
+	ty otlp.MetricDescriptor_Type) {
+
+	if sample == nil || labels == nil || tsMap == nil {
+		return
+	}
+
+	sig := timeSeriesSignature(ty, &labels)
+	ts, ok := tsMap[sig]
+
+	if ok {
+		ts.Samples = append(ts.Samples, *sample)
+	} else {
+		newTs := &prompb.TimeSeries{
+			Labels:  labels,
+			Samples: []prompb.Sample{*sample},
+		}
+		tsMap[sig] = newTs
+	}
+}
+
+// timeSeries return a string signature in the form of:
+// 		TYPE-label1-value1- ...  -labelN-valueN
+// the label slice should not contain duplicate label names; this method sorts the slice by label name before creating
+// the signature.
+func timeSeriesSignature(t otlp.MetricDescriptor_Type, labels *[]prompb.Label) string {
+	b := strings.Builder{}
+	b.WriteString(t.String())
+
+	sort.Sort(ByLabelName(*labels))
+
+	for _, lb := range *labels {
+		b.WriteString("-")
+		b.WriteString(lb.GetName())
+		b.WriteString("-")
+		b.WriteString(lb.GetValue())
+	}
+
+	return b.String()
+}
+
+// createLabelSet creates a slice of Cortex Label with OTLP labels and paris of string values.
+// Unpaired string value is ignored. String pairs overwrites OTLP labels if collision happens, and the overwrite is
+// logged. Resultant label names are sanitized.
+func createLabelSet(labels []*common.StringKeyValue, extras ...string) []prompb.Label {
+
+	// map ensures no duplicate label name
+	l := map[string]prompb.Label{}
+
+	for _, lb := range labels {
+		l[lb.Key] = prompb.Label{
+			Name:  sanitize(lb.Key),
+			Value: lb.Value,
+		}
+	}
+
+	for i := 0; i < len(extras); i += 2 {
+		if i+1 >= len(extras) {
+			break
+		}
+		_, found := l[extras[i]]
+		if found {
+			log.Println("label " + extras[i] + " is overwritten. Check if Prometheus reserved labels are used.")
+		}
+		// internal labels should be maintained
+		name := extras[i]
+		if !(len(name) > 4 && name[:2] == "__" && name[len(name)-2:] == "__") {
+			name = sanitize(name)
+		}
+		l[extras[i]] = prompb.Label{
+			Name:  name,
+			Value: extras[i+1],
+		}
+	}
+
+	s := make([]prompb.Label, 0, len(l))
+
+	for _, lb := range l {
+		s = append(s, lb)
+	}
+
+	return s
+}
+
+// getPromMetricName creates a Prometheus metric name by attaching namespace prefix, and _total suffix for Monotonic
+// metrics.
+func getPromMetricName(desc *otlp.MetricDescriptor, ns string) string {
+
+	if desc == nil {
+		return ""
+	}
+	// whether _total suffix should be applied
+	isCounter := desc.Type == otlp.MetricDescriptor_MONOTONIC_INT64 ||
+		desc.Type == otlp.MetricDescriptor_MONOTONIC_DOUBLE
+
+	b := strings.Builder{}
+
+	b.WriteString(ns)
+
+	if b.Len() > 0 {
+		b.WriteString(delimeter)
+	}
+	b.WriteString(desc.GetName())
+
+	// Including units makes two metrics with the same name and label set belong to two different TimeSeries if the
+	// units are different.
+	/*
+		if b.Len() > 0 && len(desc.GetUnit()) > 0{
+			fmt.Fprintf(&b, delimeter)
+			fmt.Fprintf(&b, desc.GetUnit())
+		}
+	*/
+
+	if b.Len() > 0 && isCounter {
+		b.WriteString(delimeter)
+		b.WriteString(totalStr)
+	}
+	return sanitize(b.String())
+}
+
+// copied from prometheus-go-metric-exporter
+// sanitize replaces non-alphanumeric characters with underscores in s.
+func sanitize(s string) string {
+	if len(s) == 0 {
+		return s
+	}
+
+	// Note: No length limit for label keys because Prometheus doesn't
+	// define a length limit, thus we should NOT be truncating label keys.
+	// See https://github.com/orijtech/prometheus-go-metrics-exporter/issues/4.
+	s = strings.Map(sanitizeRune, s)
+	if unicode.IsDigit(rune(s[0])) {
+		s = keyStr + delimeter + s
+	}
+	if s[0] == '_' {
+		s = keyStr + s
+	}
+	return s
+}
+
+// copied from prometheus-go-metric-exporter
+// sanitizeRune converts anything that is not a letter or digit to an underscore
+func sanitizeRune(r rune) rune {
+	if unicode.IsLetter(r) || unicode.IsDigit(r) {
+		return r
+	}
+	// Everything else turns into an underscore
+	return '_'
+}