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fix: drop invalid OpenMetrics 2.0 exemplars instead of failing exposition #970

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Merged
bwplotka merged 2 commits into from
Aug 25, 2026
+104 −32
Merged

fix: drop invalid OpenMetrics 2.0 exemplars instead of failing exposition #970

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5c73e4b
fix: drop invalid OpenMetrics 2.0 exemplars instead of failing exposi…
dashpole Aug 24, 2026
223e26b
expfmt: add comment explaining why invalid OpenMetrics 2.0 exemplars …
dashpole Aug 24, 2026
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16 changes: 8 additions & 8 deletions expfmt/openmetrics_2_0_create.go
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Original file line number Diff line number Diff line change
Expand Up @@ -263,7 +263,7 @@ func writeOpenMetrics20Sample(w enhancedWriter, name string, metric *dto.Metric,
}
}

if exemplar != nil && exemplar.Timestamp != nil {
if exemplar != nil {
n, err = writeExemplar20(w, exemplar)
written += n
if err != nil {
Expand All @@ -280,13 +280,14 @@ func writeOpenMetrics20Sample(w enhancedWriter, name string, metric *dto.Metric,
}

// writeExemplar20 writes the provided exemplar in OpenMetrics 2.0 format to w.
// In OpenMetrics 2.0, exemplars without a timestamp are dropped.
// In OpenMetrics 2.0, invalid exemplars or exemplars without a timestamp are dropped.
func writeExemplar20(w enhancedWriter, e *dto.Exemplar) (int, error) {
if e == nil || e.Timestamp == nil {
if e == nil {
return 0, nil
}
// In OpenMetrics 2.0, invalid exemplars are dropped rather than failing the entire exposition.
if err := validateExemplar20(e); err != nil {
return 0, err
return 0, nil
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bwplotka marked this conversation as resolved.
}
written := 0
n, err := w.WriteString(" # ")
Expand Down Expand Up @@ -318,10 +319,6 @@ func writeExemplar20(w enhancedWriter, e *dto.Exemplar) (int, error) {
if err != nil {
return written, err
}
err = e.Timestamp.CheckValid()
if err != nil {
return written, err
}
ts := e.Timestamp
n, err = writeProtoTimestamp(w, ts)
written += n
Expand Down Expand Up @@ -387,6 +384,9 @@ func containsRawNewline(s string) bool {
}

func validateExemplar20(e *dto.Exemplar) error {
if e.Timestamp == nil {
return errors.New("exemplar timestamp is required")
}
if err := e.Timestamp.CheckValid(); err != nil {
return err
}
Expand Down
120 changes: 96 additions & 24 deletions expfmt/openmetrics_2_0_create_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -205,6 +205,102 @@ http_requests_total 1027.0 # {} 1.0 1234567890.5
},
out: `# TYPE http_requests_total counter
http_requests_total 1027.0
`,
},
{
name: "CounterWithInvalidExemplarTimestamp",
in: &dto.MetricFamily{
Name: proto.String("http_requests_total"),
Type: dto.MetricType_COUNTER.Enum(),
Metric: []*dto.Metric{
{
Counter: &dto.Counter{
Value: proto.Float64(1027),
Exemplar: &dto.Exemplar{
Label: []*dto.LabelPair{
{Name: proto.String("trace_id"), Value: proto.String("1234")},
},
Value: proto.Float64(1),
Timestamp: &timestamppb.Timestamp{
Nanos: -1,
},
},
},
},
},
},
out: `# TYPE http_requests_total counter
http_requests_total 1027.0
`,
},
{
name: "CounterWithInvalidExemplarLabel",
in: &dto.MetricFamily{
Name: proto.String("http_requests_total"),
Type: dto.MetricType_COUNTER.Enum(),
Metric: []*dto.Metric{
{
Counter: &dto.Counter{
Value: proto.Float64(1027),
Exemplar: &dto.Exemplar{
Label: []*dto.LabelPair{
{Name: proto.String(""), Value: proto.String("1234")},
},
Value: proto.Float64(1),
Timestamp: &timestamppb.Timestamp{Seconds: 1234567890},
},
},
},
},
},
out: `# TYPE http_requests_total counter
http_requests_total 1027.0
`,
},
{
name: "CounterWithNewlineInExemplarLabelName",
in: &dto.MetricFamily{
Name: proto.String("http_requests_total"),
Type: dto.MetricType_COUNTER.Enum(),
Metric: []*dto.Metric{
{
Counter: &dto.Counter{
Value: proto.Float64(1027),
Exemplar: &dto.Exemplar{
Label: []*dto.LabelPair{
{Name: proto.String("trace\nid"), Value: proto.String("1234")},
},
Value: proto.Float64(1),
Timestamp: &timestamppb.Timestamp{Seconds: 1234567890},
},
},
},
},
},
out: `# TYPE http_requests_total counter
http_requests_total 1027.0
`,
},
{
name: "CounterWithNilExemplarLabelPair",
in: &dto.MetricFamily{
Name: proto.String("http_requests_total"),
Type: dto.MetricType_COUNTER.Enum(),
Metric: []*dto.Metric{
{
Counter: &dto.Counter{
Value: proto.Float64(1027),
Exemplar: &dto.Exemplar{
Label: []*dto.LabelPair{nil},
Value: proto.Float64(1),
Timestamp: &timestamppb.Timestamp{Seconds: 1234567890},
},
},
},
},
},
out: `# TYPE http_requests_total counter
http_requests_total 1027.0
`,
},
{
Expand Down Expand Up @@ -556,30 +652,6 @@ func TestCreateOpenMetrics20_Errors(t *testing.T) {
},
expectedErr: "invalid created timestamp in metric test_counter_total",
},
{
name: "ExemplarInvalidTimestamp",
in: &dto.MetricFamily{
Name: proto.String("test_counter_total"),
Type: dto.MetricType_COUNTER.Enum(),
Metric: []*dto.Metric{
{
Counter: &dto.Counter{
Value: proto.Float64(1.0),
Exemplar: &dto.Exemplar{
Label: []*dto.LabelPair{
{Name: proto.String("trace_id"), Value: proto.String("1234")},
},
Value: proto.Float64(1.0),
Timestamp: &timestamppb.Timestamp{
Nanos: -1,
},
},
},
},
},
},
expectedErr: "has out-of-range nanos",
},
}

for _, tc := range tests {
Expand Down
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