feat: implement gauge and counter support for OpenMetrics 2.0 #894
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,285 @@ | ||
| // Copyright The Prometheus 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. | ||
|
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||
| package expfmt | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "errors" | ||
| "fmt" | ||
| "io" | ||
| "math" | ||
| "strconv" | ||
|
|
||
| dto "github.com/prometheus/client_model/go" | ||
| ) | ||
|
|
||
| // MetricFamilyToOpenMetrics20 converts a MetricFamily proto message into the | ||
| // OpenMetrics text format version 2.0.0 and writes the resulting lines to 'out'. | ||
| // It returns the number of bytes written and any error encountered. | ||
| func MetricFamilyToOpenMetrics20(out io.Writer, in *dto.MetricFamily, options ...EncoderOption) (written int, err error) { | ||
| _ = options | ||
| name := in.GetName() | ||
| if name == "" { | ||
| return 0, fmt.Errorf("MetricFamily has no name: %s", in) | ||
| } | ||
|
|
||
| // Try the interface upgrade. If it doesn't work, we'll use a | ||
| // bufio.Writer from the sync.Pool. | ||
| w, ok := out.(enhancedWriter) | ||
| if !ok { | ||
| b := bufPool.Get().(*bufio.Writer) | ||
| b.Reset(out) | ||
| w = b | ||
| defer func() { | ||
| bErr := b.Flush() | ||
| if err == nil { | ||
| err = bErr | ||
| } | ||
| bufPool.Put(b) | ||
| }() | ||
| } | ||
|
|
||
| var ( | ||
| n int | ||
| metricType = in.GetType() | ||
| ) | ||
|
|
||
| // Comments, first HELP, then TYPE. | ||
| if in.Help != nil { | ||
| n, err = w.WriteString("# HELP ") | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeName(w, name) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| err = w.WriteByte(' ') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeEscapedString(w, *in.Help, true) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| err = w.WriteByte('\n') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
| n, err = w.WriteString("# TYPE ") | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeName(w, name) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| switch metricType { | ||
| case dto.MetricType_COUNTER: | ||
| n, err = w.WriteString(" counter\n") | ||
| case dto.MetricType_GAUGE: | ||
| n, err = w.WriteString(" gauge\n") | ||
| case dto.MetricType_SUMMARY: | ||
| n, err = w.WriteString(" summary\n") | ||
| case dto.MetricType_UNTYPED: | ||
| n, err = w.WriteString(" unknown\n") | ||
| case dto.MetricType_HISTOGRAM: | ||
| n, err = w.WriteString(" histogram\n") | ||
| case dto.MetricType_GAUGE_HISTOGRAM: | ||
| n, err = w.WriteString(" gaugehistogram\n") | ||
| default: | ||
|
dashpole marked this conversation as resolved.
|
||
| return written, fmt.Errorf("unknown metric type %s", metricType.String()) | ||
| } | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| if in.Unit != nil { | ||
| n, err = w.WriteString("# UNIT ") | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeName(w, name) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
|
|
||
| err = w.WriteByte(' ') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeEscapedString(w, *in.Unit, true) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| err = w.WriteByte('\n') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
|
|
||
| // Finally the samples, one line for each. | ||
| for _, metric := range in.Metric { | ||
| switch metricType { | ||
| case dto.MetricType_COUNTER: | ||
| if metric.Counter == nil { | ||
| return written, fmt.Errorf("expected counter in metric %s %s", name, metric) | ||
| } | ||
| n, err = writeOpenMetrics20Sample(w, name, metric, metric.Counter.GetValue(), 0, false, metric.Counter.Exemplar) | ||
| case dto.MetricType_GAUGE: | ||
| if metric.Gauge == nil { | ||
| return written, fmt.Errorf("expected gauge in metric %s %s", name, metric) | ||
| } | ||
| n, err = writeOpenMetrics20Sample(w, name, metric, metric.Gauge.GetValue(), 0, false, nil) | ||
| case dto.MetricType_UNTYPED: | ||
| if metric.Untyped == nil { | ||
| return written, fmt.Errorf("expected untyped in metric %s %s", name, metric) | ||
| } | ||
| n, err = writeOpenMetrics20Sample(w, name, metric, metric.Untyped.GetValue(), 0, false, nil) | ||
| case dto.MetricType_SUMMARY: | ||
| if metric.Summary == nil { | ||
| return written, fmt.Errorf("expected summary in metric %s %s", name, metric) | ||
| } | ||
| n, err = writeCompositeSummary(w, name, metric) | ||
| case dto.MetricType_HISTOGRAM, dto.MetricType_GAUGE_HISTOGRAM: | ||
| if metric.Histogram == nil { | ||
| return written, fmt.Errorf("expected histogram in metric %s %s", name, metric) | ||
| } | ||
| n, err = writeCompositeHistogram(w, name, metric, metricType == dto.MetricType_GAUGE_HISTOGRAM) | ||
|
dashpole marked this conversation as resolved.
|
||
| default: | ||
| return written, fmt.Errorf("unexpected type in metric %s %s", name, metric) | ||
| } | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
| return written, nil | ||
| } | ||
|
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| // writeOpenMetrics20Sample writes a single sample for simple types (Counter, Gauge, Untyped). | ||
| func writeOpenMetrics20Sample(w enhancedWriter, name string, metric *dto.Metric, floatValue float64, intValue uint64, useIntValue bool, exemplar *dto.Exemplar) (int, error) { | ||
| written := 0 | ||
| n, err := writeOpenMetricsNameAndLabelPairs(w, name, metric.Label, "", 0) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| err = w.WriteByte(' ') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
|
|
||
| if useIntValue { | ||
| n, err = writeUint(w, intValue) | ||
| } else { | ||
| n, err = writeFloat(w, floatValue) | ||
| } | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
|
|
||
| if metric.TimestampMs != nil { | ||
| err = w.WriteByte(' ') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| n, err = writeOpenMetrics20Timestamp(w, float64(*metric.TimestampMs)/1000) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
|
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||
| // Start Timestamp for Counter | ||
| if metric.Counter != nil && metric.Counter.CreatedTimestamp != nil { | ||
| n, err = w.WriteString(" st@") | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| ts := metric.Counter.CreatedTimestamp | ||
| n, err = writeOpenMetrics20Timestamp(w, float64(ts.GetSeconds())+float64(ts.GetNanos())/1e9) | ||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
|
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| if exemplar != nil && len(exemplar.Label) > 0 { | ||
| n, err = writeExemplar(w, exemplar) | ||
|
Member
There was a problem hiding this comment. I don't think we can call this function as is. It treats the exemplar timestamp as optional. I think we need to drop exemplars without timestamp for om2.0. https://prometheus.io/docs/specs/om/open_metrics_spec_2_0/#exemplars
Member
There was a problem hiding this comment. According to LLM, client_golang at least always sets the timestamp, so it will not be breaking to do this, i.e. drop exemplars without timestamp. |
||
| written += n | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| } | ||
|
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| err = w.WriteByte('\n') | ||
| written++ | ||
| if err != nil { | ||
| return written, err | ||
| } | ||
| return written, nil | ||
| } | ||
|
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| // writeOpenMetrics20Timestamp writes a float64 as a timestamp without scientific notation. | ||
| func writeOpenMetrics20Timestamp(w enhancedWriter, f float64) (int, error) { | ||
| switch { | ||
| case math.IsNaN(f): | ||
| return w.WriteString("NaN") | ||
| case math.IsInf(f, +1): | ||
| return w.WriteString("+Inf") | ||
| case math.IsInf(f, -1): | ||
| return w.WriteString("-Inf") | ||
| default: | ||
| bp := numBufPool.Get().(*[]byte) | ||
| *bp = strconv.AppendFloat((*bp)[:0], f, 'f', -1, 64) | ||
| written, err := w.Write(*bp) | ||
| numBufPool.Put(bp) | ||
| return written, err | ||
| } | ||
| } | ||
|
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| // Stubs for Summary and Histogram | ||
|
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| func writeCompositeSummary(w enhancedWriter, name string, metric *dto.Metric) (int, error) { | ||
| _ = w | ||
|
dashpole marked this conversation as resolved.
|
||
| _ = name | ||
| _ = metric | ||
| return 0, errors.New("summary not implemented yet") | ||
| } | ||
|
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| func writeCompositeHistogram(w enhancedWriter, name string, metric *dto.Metric, isGauge bool) (int, error) { | ||
| _ = w | ||
| _ = name | ||
| _ = metric | ||
| _ = isGauge | ||
| return 0, errors.New("histogram not implemented yet") | ||
| } | ||
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