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Prometheus exporter: omit empty otel_scope_info and otel_target_info metrics #6816

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Prometheus exporter: omit empty otel_scope_info and otel_target_info metrics #6816

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20 changes: 14 additions & 6 deletions exporters/prometheus/exporter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,9 @@ const (
)

var (
errScopeInvalid = errors.New("invalid scope")
errScopeInvalid = errors.New("invalid scope")
errEmptyOtelScopeInfo = errors.New("empty otel_scope_info")
errEmptyOtelTargetInfo = errors.New("empty otel_target_info")

metricsPool = sync.Pool{
New: func() interface{} {
Expand Down Expand Up @@ -176,7 +178,7 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
if c.targetInfo == nil && !c.disableTargetInfo {
targetInfo, err := createInfoMetric(targetInfoMetricName, targetInfoDescription, metrics.Resource)
if err != nil {
// If the target info metric is invalid, disable sending it.
// If the target info metric is invalid or empty, disable sending it.
c.disableTargetInfo = true
otel.Handle(err)
return
Expand All @@ -186,7 +188,7 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
}
}()

if !c.disableTargetInfo {
if !c.disableTargetInfo && c.targetInfo != nil {
ch <- c.targetInfo
}

Expand All @@ -203,8 +205,8 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {

if !c.disableScopeInfo {
scopeInfo, err := c.scopeInfo(scopeMetrics.Scope)
if errors.Is(err, errScopeInvalid) {
// Do not report the same error multiple times.
if errors.Is(err, errScopeInvalid) || scopeInfo == nil {
// Do not report the same error multiple times or if scopeInfo is nil.
continue
}
if err != nil {
Expand Down Expand Up @@ -435,13 +437,19 @@ func getAttrs(attrs attribute.Set) ([]string, []string) {
}

func createInfoMetric(name, description string, res *resource.Resource) (prometheus.Metric, error) {
if res.Set().Len() == 0 {
return nil, errEmptyOtelTargetInfo
}
keys, values := getAttrs(*res.Set())
desc := prometheus.NewDesc(name, description, keys, nil)
return prometheus.NewConstMetric(desc, prometheus.GaugeValue, float64(1), values...)
}

func createScopeInfoMetric(scope instrumentation.Scope) (prometheus.Metric, error) {
attrs := make([]attribute.KeyValue, 0, scope.Attributes.Len()+2) // resource attrs + scope name + scope version
if scope.Attributes.Len() == 0 {
return nil, errEmptyOtelScopeInfo
}
attrs := make([]attribute.KeyValue, 0, scope.Attributes.Len()+2)
attrs = append(attrs, scope.Attributes.ToSlice()...)
attrs = append(attrs, attribute.String(scopeNameLabel, scope.Name))
attrs = append(attrs, attribute.String(scopeVersionLabel, scope.Version))
Expand Down
4 changes: 3 additions & 1 deletion exporters/prometheus/exporter_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -305,7 +305,9 @@ func TestPrometheusExporter(t *testing.T) {
name: "empty resource",
emptyResource: true,
expectedFile: "testdata/empty_resource.txt",
recordMetrics: func(ctx context.Context, meter otelmetric.Meter) {
recordMetrics: func(ctx context.Context, _ otelmetric.Meter) {
// No instrumentation name/version/attributes
meter := metric.NewMeterProvider().Meter("")
opt := otelmetric.WithAttributes(
attribute.Key("A").String("B"),
attribute.Key("C").String("D"),
Expand Down
9 changes: 0 additions & 9 deletions exporters/prometheus/testdata/empty_resource.txt
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Original file line number Diff line number Diff line change
@@ -1,9 +0,0 @@
# HELP foo_total a simple counter
# TYPE foo_total counter
foo_total{A="B",C="D",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 24.3
# HELP otel_scope_info Instrumentation Scope metadata
# TYPE otel_scope_info gauge
otel_scope_info{fizz="buzz",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 1
# HELP target_info Target metadata
# TYPE target_info gauge
target_info 1
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