Adds a new config StartTimeMetricRegex

Previously the prometheus receiver only accepts
`process_start_time_metric` as the start time when UseStartTimeMetric is
set. For applications that export similar metrics but with a prefix,
e.g., via NewProcessCollector(namespace), the receiver would drop such
metrics.
By adding StartTimeMetricRegex, at least we will be able to cover such
use cases.

receiver/prometheusreceiver/config.go

@@ -29,6 +29,7 @@ type Config struct {
 	BufferPeriod                  time.Duration  `mapstructure:"buffer_period"`
 	BufferCount                   int            `mapstructure:"buffer_count"`
 	UseStartTimeMetric            bool           `mapstructure:"use_start_time_metric"`
+	StartTimeMetricRegex          string         `mapstructure:"start_time_metric_regex"`
 
 	// ConfigPlaceholder is just an entry to make the configuration pass a check
 	// that requires that all keys present in the config actually exist on the

receiver/prometheusreceiver/config_test.go

@@ -54,6 +54,7 @@ func TestLoadConfig(t *testing.T) {
 	assert.Equal(t, r1.PrometheusConfig.ScrapeConfigs[0].JobName, "demo")
 	assert.Equal(t, time.Duration(r1.PrometheusConfig.ScrapeConfigs[0].ScrapeInterval), 5*time.Second)
 	assert.Equal(t, r1.UseStartTimeMetric, true)
+	assert.Equal(t, r1.StartTimeMetricRegex, "^(.+_)*process_start_time_seconds$")
 }
 
 func TestLoadConfigWithEnvVar(t *testing.T) {

receiver/prometheusreceiver/internal/metricsbuilder.go

@@ -17,6 +17,7 @@ package internal
 import (
 	"errors"
 	"fmt"
+	"regexp"
 	"strconv"
 	"strings"
 
@@ -51,33 +52,46 @@ var (
 )
 
 type metricBuilder struct {
-	hasData            bool
-	hasInternalMetric  bool
-	mc                 MetadataCache
-	metrics            []*metricspb.Metric
-	numTimeseries      int
-	droppedTimeseries  int
-	useStartTimeMetric bool
-	startTime          float64
-	scrapeLatencyMs    float64
-	scrapeStatus       string
-	logger             *zap.Logger
-	currentMf          MetricFamily
+	hasData              bool
+	hasInternalMetric    bool
+	mc                   MetadataCache
+	metrics              []*metricspb.Metric
+	numTimeseries        int
+	droppedTimeseries    int
+	useStartTimeMetric   bool
+	startTimeMetricRegex *regexp.Regexp
+	startTime            float64
+	scrapeLatencyMs      float64
+	scrapeStatus         string
+	logger               *zap.Logger
+	currentMf            MetricFamily
 }
 
 // newMetricBuilder creates a MetricBuilder which is allowed to feed all the datapoints from a single prometheus
 // scraped page by calling its AddDataPoint function, and turn them into an opencensus data.MetricsData object
 // by calling its Build function
-func newMetricBuilder(mc MetadataCache, useStartTimeMetric bool, logger *zap.Logger) *metricBuilder {
-
+func newMetricBuilder(mc MetadataCache, useStartTimeMetric bool, startTimeMetricRegex string, logger *zap.Logger) *metricBuilder {
+	var regex *regexp.Regexp
+	if startTimeMetricRegex != "" {
+		regex, _ = regexp.Compile(startTimeMetricRegex)
+	}
 	return &metricBuilder{
-		mc:                 mc,
-		metrics:            make([]*metricspb.Metric, 0),
-		logger:             logger,
-		numTimeseries:      0,
-		droppedTimeseries:  0,
-		useStartTimeMetric: useStartTimeMetric,
+		mc:                   mc,
+		metrics:              make([]*metricspb.Metric, 0),
+		logger:               logger,
+		numTimeseries:        0,
+		droppedTimeseries:    0,
+		useStartTimeMetric:   useStartTimeMetric,
+		startTimeMetricRegex: regex,
+	}
+}
+
+func (b *metricBuilder) matchStartTimeMetric(metricName string) bool {
+	if b.startTimeMetricRegex != nil {
+		return b.startTimeMetricRegex.MatchString(metricName)
 	}
+
+	return metricName == startTimeMetricName
 }
 
 // AddDataPoint is for feeding prometheus data complexValue in its processing order
@@ -104,7 +118,7 @@ func (b *metricBuilder) AddDataPoint(ls labels.Labels, t int64, v float64) error
 			b.scrapeLatencyMs = v * 1000
 		}
 		return nil
-	case b.useStartTimeMetric && metricName == startTimeMetricName:
+	case b.useStartTimeMetric && b.matchStartTimeMetric(metricName):
 		b.startTime = v
 	}
 

receiver/prometheusreceiver/internal/metricsbuilder_test.go

@@ -29,6 +29,7 @@ import (
 
 const startTs = int64(1555366610000)
 const interval = int64(15 * 1000)
+const defaultBuilderStartTime = float64(1.0)
 
 var testMetadata = map[string]scrape.MetricMetadata{
 	"counter_test":    {Metric: "counter_test", Type: textparse.MetricTypeCounter, Help: "", Unit: ""},
@@ -44,6 +45,12 @@ var testMetadata = map[string]scrape.MetricMetadata{
 	"poor_name_count": {Metric: "poor_name_count", Type: textparse.MetricTypeCounter, Help: "", Unit: ""},
 	"up":              {Metric: "up", Type: textparse.MetricTypeCounter, Help: "", Unit: ""},
 	"scrape_foo":      {Metric: "scrape_foo", Type: textparse.MetricTypeCounter, Help: "", Unit: ""},
+	"example_process_start_time_seconds": {Metric: "example_process_start_time_seconds",
+		Type: textparse.MetricTypeGauge, Help: "", Unit: ""},
+	"process_start_time_seconds": {Metric: "process_start_time_seconds",
+		Type: textparse.MetricTypeGauge, Help: "", Unit: ""},
+	"badprocess_start_time_seconds": {Metric: "badprocess_start_time_seconds",
+		Type: textparse.MetricTypeGauge, Help: "", Unit: ""},
 }
 
 type testDataPoint struct {
@@ -90,8 +97,8 @@ func runBuilderTests(t *testing.T, tests []buildTestData) {
 			mc := newMockMetadataCache(testMetadata)
 			st := startTs
 			for i, page := range tt.inputs {
-				b := newMetricBuilder(mc, true, testLogger)
-				b.startTime = 1.0 // set to a non-zero value
+				b := newMetricBuilder(mc, true, "", testLogger)
+				b.startTime = defaultBuilderStartTime // set to a non-zero value
 				for _, pt := range page.pts {
 					// set ts for testing
 					pt.t = st
@@ -106,6 +113,85 @@ func runBuilderTests(t *testing.T, tests []buildTestData) {
 	}
 }
 
+func runBuilderStartTimeTests(t *testing.T, tests []buildTestData,
+	startTimeMetricRegex string, expectedBuilderStartTime float64) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mc := newMockMetadataCache(testMetadata)
+			st := startTs
+			for _, page := range tt.inputs {
+				b := newMetricBuilder(mc, true, startTimeMetricRegex,
+					testLogger)
+				b.startTime = defaultBuilderStartTime // set to a non-zero value
+				for _, pt := range page.pts {
+					// set ts for testing
+					pt.t = st
+					assert.NoError(t, b.AddDataPoint(pt.lb, pt.t, pt.v))
+				}
+				_, _, _, err := b.Build()
+				assert.NoError(t, err)
+				assert.EqualValues(t, b.startTime, expectedBuilderStartTime)
+				st += interval
+			}
+		})
+	}
+}
+
+func Test_startTimeMetricMatch(t *testing.T) {
+	matchBuilderStartTime := float64(123.456)
+	matchTests := []buildTestData{
+		{
+			name: "prefix_match",
+			inputs: []*testScrapedPage{
+				{
+					pts: []*testDataPoint{
+						createDataPoint("example_process_start_time_seconds",
+							matchBuilderStartTime, "foo", "bar"),
+					},
+				},
+			},
+		},
+		{
+			name: "match",
+			inputs: []*testScrapedPage{
+				{
+					pts: []*testDataPoint{
+						createDataPoint("process_start_time_seconds",
+							matchBuilderStartTime, "foo", "bar"),
+					},
+				},
+			},
+		},
+	}
+	nomatchTests := []buildTestData{
+		{
+			name: "nomatch1",
+			inputs: []*testScrapedPage{
+				{
+					pts: []*testDataPoint{
+						createDataPoint("_process_start_time_seconds",
+							matchBuilderStartTime, "foo", "bar"),
+					},
+				},
+			},
+		},
+		{
+			name: "nomatch2",
+			inputs: []*testScrapedPage{
+				{
+					pts: []*testDataPoint{
+						createDataPoint("subprocess_start_time_seconds",
+							matchBuilderStartTime, "foo", "bar"),
+					},
+				},
+			},
+		},
+	}
+
+	runBuilderStartTimeTests(t, matchTests, "^(.+_)*process_start_time_seconds$", matchBuilderStartTime)
+	runBuilderStartTimeTests(t, nomatchTests, "^(.+_)*process_start_time_seconds$", defaultBuilderStartTime)
+}
+
 func Test_metricBuilder_counters(t *testing.T) {
 	tests := []buildTestData{
 		{
@@ -1055,7 +1141,7 @@ func Test_metricBuilder_skipped(t *testing.T) {
 func Test_metricBuilder_baddata(t *testing.T) {
 	t.Run("empty-metric-name", func(t *testing.T) {
 		mc := newMockMetadataCache(testMetadata)
-		b := newMetricBuilder(mc, true, testLogger)
+		b := newMetricBuilder(mc, true, "", testLogger)
 		b.startTime = 1.0 // set to a non-zero value
 		if err := b.AddDataPoint(labels.FromStrings("a", "b"), startTs, 123); err != errMetricNameNotFound {
 			t.Error("expecting errMetricNameNotFound error, but get nil")
@@ -1069,7 +1155,7 @@ func Test_metricBuilder_baddata(t *testing.T) {
 
 	t.Run("histogram-datapoint-no-bucket-label", func(t *testing.T) {
 		mc := newMockMetadataCache(testMetadata)
-		b := newMetricBuilder(mc, true, testLogger)
+		b := newMetricBuilder(mc, true, "", testLogger)
 		b.startTime = 1.0 // set to a non-zero value
 		if err := b.AddDataPoint(createLabels("hist_test", "k", "v"), startTs, 123); err != errEmptyBoundaryLabel {
 			t.Error("expecting errEmptyBoundaryLabel error, but get nil")
@@ -1078,7 +1164,7 @@ func Test_metricBuilder_baddata(t *testing.T) {
 
 	t.Run("summary-datapoint-no-quantile-label", func(t *testing.T) {
 		mc := newMockMetadataCache(testMetadata)
-		b := newMetricBuilder(mc, true, testLogger)
+		b := newMetricBuilder(mc, true, "", testLogger)
 		b.startTime = 1.0 // set to a non-zero value
 		if err := b.AddDataPoint(createLabels("summary_test", "k", "v"), startTs, 123); err != errEmptyBoundaryLabel {
 			t.Error("expecting errEmptyBoundaryLabel error, but get nil")

receiver/prometheusreceiver/internal/ocastore.go

@@ -47,28 +47,30 @@ type OcaStore interface {
 
 // OpenCensus Store for prometheus
 type ocaStore struct {
-	running            int32
-	logger             *zap.Logger
-	sink               consumer.MetricsConsumer
-	mc                 *mService
-	once               *sync.Once
-	ctx                context.Context
-	jobsMap            *JobsMap
-	useStartTimeMetric bool
-	receiverName       string
+	running              int32
+	logger               *zap.Logger
+	sink                 consumer.MetricsConsumer
+	mc                   *mService
+	once                 *sync.Once
+	ctx                  context.Context
+	jobsMap              *JobsMap
+	useStartTimeMetric   bool
+	startTimeMetricRegex string
+	receiverName         string
 }
 
 // NewOcaStore returns an ocaStore instance, which can be acted as prometheus' scrape.Appendable
-func NewOcaStore(ctx context.Context, sink consumer.MetricsConsumer, logger *zap.Logger, jobsMap *JobsMap, useStartTimeMetric bool, receiverName string) OcaStore {
+func NewOcaStore(ctx context.Context, sink consumer.MetricsConsumer, logger *zap.Logger, jobsMap *JobsMap, useStartTimeMetric bool, startTimeMetricRegex string, receiverName string) OcaStore {
 	return &ocaStore{
-		running:            runningStateInit,
-		ctx:                ctx,
-		sink:               sink,
-		logger:             logger,
-		once:               &sync.Once{},
-		jobsMap:            jobsMap,
-		useStartTimeMetric: useStartTimeMetric,
-		receiverName:       receiverName,
+		running:              runningStateInit,
+		ctx:                  ctx,
+		sink:                 sink,
+		logger:               logger,
+		once:                 &sync.Once{},
+		jobsMap:              jobsMap,
+		useStartTimeMetric:   useStartTimeMetric,
+		startTimeMetricRegex: startTimeMetricRegex,
+		receiverName:         receiverName,
 	}
 }
 
@@ -83,7 +85,7 @@ func (o *ocaStore) SetScrapeManager(scrapeManager *scrape.Manager) {
 func (o *ocaStore) Appender() storage.Appender {
 	state := atomic.LoadInt32(&o.running)
 	if state == runningStateReady {
-		return newTransaction(o.ctx, o.jobsMap, o.useStartTimeMetric, o.receiverName, o.mc, o.sink, o.logger)
+		return newTransaction(o.ctx, o.jobsMap, o.useStartTimeMetric, o.startTimeMetricRegex, o.receiverName, o.mc, o.sink, o.logger)
 	} else if state == runningStateInit {
 		panic("ScrapeManager is not set")
 	}

receiver/prometheusreceiver/internal/ocastore_test.go

@@ -26,7 +26,7 @@ import (
 
 func TestOcaStore(t *testing.T) {
 
-	o := NewOcaStore(context.Background(), nil, nil, nil, false, "prometheus")
+	o := NewOcaStore(context.Background(), nil, nil, nil, false, "", "prometheus")
 	o.SetScrapeManager(&scrape.Manager{})
 
 	app := o.Appender()

receiver/prometheusreceiver/internal/transaction.go

@@ -57,32 +57,34 @@ var errNoJobInstance = errors.New("job or instance cannot be found from labels")
 // will be flush to the downstream consumer, or Rollback, which means discard all the data, is called and all data
 // points are discarded.
 type transaction struct {
-	id                 int64
-	ctx                context.Context
-	isNew              bool
-	sink               consumer.MetricsConsumer
-	job                string
-	instance           string
-	jobsMap            *JobsMap
-	useStartTimeMetric bool
-	receiverName       string
-	ms                 MetadataService
-	node               *commonpb.Node
-	metricBuilder      *metricBuilder
-	logger             *zap.Logger
+	id                   int64
+	ctx                  context.Context
+	isNew                bool
+	sink                 consumer.MetricsConsumer
+	job                  string
+	instance             string
+	jobsMap              *JobsMap
+	useStartTimeMetric   bool
+	startTimeMetricRegex string
+	receiverName         string
+	ms                   MetadataService
+	node                 *commonpb.Node
+	metricBuilder        *metricBuilder
+	logger               *zap.Logger
 }
 
-func newTransaction(ctx context.Context, jobsMap *JobsMap, useStartTimeMetric bool, receiverName string, ms MetadataService, sink consumer.MetricsConsumer, logger *zap.Logger) *transaction {
+func newTransaction(ctx context.Context, jobsMap *JobsMap, useStartTimeMetric bool, startTimeMetricRegex string, receiverName string, ms MetadataService, sink consumer.MetricsConsumer, logger *zap.Logger) *transaction {
 	return &transaction{
-		id:                 atomic.AddInt64(&idSeq, 1),
-		ctx:                ctx,
-		isNew:              true,
-		sink:               sink,
-		jobsMap:            jobsMap,
-		useStartTimeMetric: useStartTimeMetric,
-		receiverName:       receiverName,
-		ms:                 ms,
-		logger:             logger,
+		id:                   atomic.AddInt64(&idSeq, 1),
+		ctx:                  ctx,
+		isNew:                true,
+		sink:                 sink,
+		jobsMap:              jobsMap,
+		useStartTimeMetric:   useStartTimeMetric,
+		startTimeMetricRegex: startTimeMetricRegex,
+		receiverName:         receiverName,
+		ms:                   ms,
+		logger:               logger,
 	}
 }
 
@@ -133,7 +135,7 @@ func (tr *transaction) initTransaction(ls labels.Labels) error {
 		tr.instance = instance
 	}
 	tr.node = createNode(job, instance, mc.SharedLabels().Get(model.SchemeLabel))
-	tr.metricBuilder = newMetricBuilder(mc, tr.useStartTimeMetric, tr.logger)
+	tr.metricBuilder = newMetricBuilder(mc, tr.useStartTimeMetric, tr.startTimeMetricRegex, tr.logger)
 	tr.isNew = false
 	return nil
 }