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- // Copyright 2020 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.
- package expfmt
- import (
- "bufio"
- "bytes"
- "fmt"
- "io"
- "math"
- "strconv"
- "strings"
- "github.com/golang/protobuf/ptypes"
- "github.com/prometheus/common/model"
- dto "github.com/prometheus/client_model/go"
- )
- // MetricFamilyToOpenMetrics converts a MetricFamily proto message into the
- // OpenMetrics text format and writes the resulting lines to 'out'. It returns
- // the number of bytes written and any error encountered. The output will have
- // the same order as the input, no further sorting is performed. Furthermore,
- // this function assumes the input is already sanitized and does not perform any
- // sanity checks. If the input contains duplicate metrics or invalid metric or
- // label names, the conversion will result in invalid text format output.
- //
- // This function fulfills the type 'expfmt.encoder'.
- //
- // Note that OpenMetrics requires a final `# EOF` line. Since this function acts
- // on individual metric families, it is the responsibility of the caller to
- // append this line to 'out' once all metric families have been written.
- // Conveniently, this can be done by calling FinalizeOpenMetrics.
- //
- // The output should be fully OpenMetrics compliant. However, there are a few
- // missing features and peculiarities to avoid complications when switching from
- // Prometheus to OpenMetrics or vice versa:
- //
- // - Counters are expected to have the `_total` suffix in their metric name. In
- // the output, the suffix will be truncated from the `# TYPE` and `# HELP`
- // line. A counter with a missing `_total` suffix is not an error. However,
- // its type will be set to `unknown` in that case to avoid invalid OpenMetrics
- // output.
- //
- // - No support for the following (optional) features: `# UNIT` line, `_created`
- // line, info type, stateset type, gaugehistogram type.
- //
- // - The size of exemplar labels is not checked (i.e. it's possible to create
- // exemplars that are larger than allowed by the OpenMetrics specification).
- //
- // - The value of Counters is not checked. (OpenMetrics doesn't allow counters
- // with a `NaN` value.)
- func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int, err error) {
- 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()
- shortName = name
- )
- if metricType == dto.MetricType_COUNTER && strings.HasSuffix(shortName, "_total") {
- shortName = name[:len(name)-6]
- }
- // Comments, first HELP, then TYPE.
- if in.Help != nil {
- n, err = w.WriteString("# HELP ")
- written += n
- if err != nil {
- return
- }
- n, err = w.WriteString(shortName)
- written += n
- if err != nil {
- return
- }
- err = w.WriteByte(' ')
- written++
- if err != nil {
- return
- }
- n, err = writeEscapedString(w, *in.Help, true)
- written += n
- if err != nil {
- return
- }
- err = w.WriteByte('\n')
- written++
- if err != nil {
- return
- }
- }
- n, err = w.WriteString("# TYPE ")
- written += n
- if err != nil {
- return
- }
- n, err = w.WriteString(shortName)
- written += n
- if err != nil {
- return
- }
- switch metricType {
- case dto.MetricType_COUNTER:
- if strings.HasSuffix(name, "_total") {
- n, err = w.WriteString(" counter\n")
- } else {
- n, err = w.WriteString(" unknown\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")
- default:
- return written, fmt.Errorf("unknown metric type %s", metricType.String())
- }
- written += n
- if err != nil {
- return
- }
- // 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,
- )
- }
- // Note that we have ensured above that either the name
- // ends on `_total` or that the rendered type is
- // `unknown`. Therefore, no `_total` must be added here.
- n, err = writeOpenMetricsSample(
- w, name, "", metric, "", 0,
- 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 = writeOpenMetricsSample(
- w, name, "", metric, "", 0,
- 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 = writeOpenMetricsSample(
- w, name, "", metric, "", 0,
- 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,
- )
- }
- for _, q := range metric.Summary.Quantile {
- n, err = writeOpenMetricsSample(
- w, name, "", metric,
- model.QuantileLabel, q.GetQuantile(),
- q.GetValue(), 0, false,
- nil,
- )
- written += n
- if err != nil {
- return
- }
- }
- n, err = writeOpenMetricsSample(
- w, name, "_sum", metric, "", 0,
- metric.Summary.GetSampleSum(), 0, false,
- nil,
- )
- written += n
- if err != nil {
- return
- }
- n, err = writeOpenMetricsSample(
- w, name, "_count", metric, "", 0,
- 0, metric.Summary.GetSampleCount(), true,
- nil,
- )
- case dto.MetricType_HISTOGRAM:
- if metric.Histogram == nil {
- return written, fmt.Errorf(
- "expected histogram in metric %s %s", name, metric,
- )
- }
- infSeen := false
- for _, b := range metric.Histogram.Bucket {
- n, err = writeOpenMetricsSample(
- w, name, "_bucket", metric,
- model.BucketLabel, b.GetUpperBound(),
- 0, b.GetCumulativeCount(), true,
- b.Exemplar,
- )
- written += n
- if err != nil {
- return
- }
- if math.IsInf(b.GetUpperBound(), +1) {
- infSeen = true
- }
- }
- if !infSeen {
- n, err = writeOpenMetricsSample(
- w, name, "_bucket", metric,
- model.BucketLabel, math.Inf(+1),
- 0, metric.Histogram.GetSampleCount(), true,
- nil,
- )
- written += n
- if err != nil {
- return
- }
- }
- n, err = writeOpenMetricsSample(
- w, name, "_sum", metric, "", 0,
- metric.Histogram.GetSampleSum(), 0, false,
- nil,
- )
- written += n
- if err != nil {
- return
- }
- n, err = writeOpenMetricsSample(
- w, name, "_count", metric, "", 0,
- 0, metric.Histogram.GetSampleCount(), true,
- nil,
- )
- default:
- return written, fmt.Errorf(
- "unexpected type in metric %s %s", name, metric,
- )
- }
- written += n
- if err != nil {
- return
- }
- }
- return
- }
- // FinalizeOpenMetrics writes the final `# EOF\n` line required by OpenMetrics.
- func FinalizeOpenMetrics(w io.Writer) (written int, err error) {
- return w.Write([]byte("# EOF\n"))
- }
- // writeOpenMetricsSample writes a single sample in OpenMetrics text format to
- // w, given the metric name, the metric proto message itself, optionally an
- // additional label name with a float64 value (use empty string as label name if
- // not required), the value (optionally as float64 or uint64, determined by
- // useIntValue), and optionally an exemplar (use nil if not required). The
- // function returns the number of bytes written and any error encountered.
- func writeOpenMetricsSample(
- w enhancedWriter,
- name, suffix string,
- metric *dto.Metric,
- additionalLabelName string, additionalLabelValue float64,
- floatValue float64, intValue uint64, useIntValue bool,
- exemplar *dto.Exemplar,
- ) (int, error) {
- var written int
- n, err := w.WriteString(name)
- written += n
- if err != nil {
- return written, err
- }
- if suffix != "" {
- n, err = w.WriteString(suffix)
- written += n
- if err != nil {
- return written, err
- }
- }
- n, err = writeOpenMetricsLabelPairs(
- w, metric.Label, additionalLabelName, additionalLabelValue,
- )
- 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 = writeOpenMetricsFloat(w, floatValue)
- }
- written += n
- if err != nil {
- return written, err
- }
- if metric.TimestampMs != nil {
- err = w.WriteByte(' ')
- written++
- if err != nil {
- return written, err
- }
- // TODO(beorn7): Format this directly without converting to a float first.
- n, err = writeOpenMetricsFloat(w, float64(*metric.TimestampMs)/1000)
- written += n
- if err != nil {
- return written, err
- }
- }
- if exemplar != nil {
- n, err = writeExemplar(w, exemplar)
- written += n
- if err != nil {
- return written, err
- }
- }
- err = w.WriteByte('\n')
- written++
- if err != nil {
- return written, err
- }
- return written, nil
- }
- // writeOpenMetricsLabelPairs works like writeOpenMetrics but formats the float
- // in OpenMetrics style.
- func writeOpenMetricsLabelPairs(
- w enhancedWriter,
- in []*dto.LabelPair,
- additionalLabelName string, additionalLabelValue float64,
- ) (int, error) {
- if len(in) == 0 && additionalLabelName == "" {
- return 0, nil
- }
- var (
- written int
- separator byte = '{'
- )
- for _, lp := range in {
- err := w.WriteByte(separator)
- written++
- if err != nil {
- return written, err
- }
- n, err := w.WriteString(lp.GetName())
- written += n
- if err != nil {
- return written, err
- }
- n, err = w.WriteString(`="`)
- written += n
- if err != nil {
- return written, err
- }
- n, err = writeEscapedString(w, lp.GetValue(), true)
- written += n
- if err != nil {
- return written, err
- }
- err = w.WriteByte('"')
- written++
- if err != nil {
- return written, err
- }
- separator = ','
- }
- if additionalLabelName != "" {
- err := w.WriteByte(separator)
- written++
- if err != nil {
- return written, err
- }
- n, err := w.WriteString(additionalLabelName)
- written += n
- if err != nil {
- return written, err
- }
- n, err = w.WriteString(`="`)
- written += n
- if err != nil {
- return written, err
- }
- n, err = writeOpenMetricsFloat(w, additionalLabelValue)
- written += n
- if err != nil {
- return written, err
- }
- err = w.WriteByte('"')
- written++
- if err != nil {
- return written, err
- }
- }
- err := w.WriteByte('}')
- written++
- if err != nil {
- return written, err
- }
- return written, nil
- }
- // writeExemplar writes the provided exemplar in OpenMetrics format to w. The
- // function returns the number of bytes written and any error encountered.
- func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
- written := 0
- n, err := w.WriteString(" # ")
- written += n
- if err != nil {
- return written, err
- }
- n, err = writeOpenMetricsLabelPairs(w, e.Label, "", 0)
- written += n
- if err != nil {
- return written, err
- }
- err = w.WriteByte(' ')
- written++
- if err != nil {
- return written, err
- }
- n, err = writeOpenMetricsFloat(w, e.GetValue())
- written += n
- if err != nil {
- return written, err
- }
- if e.Timestamp != nil {
- err = w.WriteByte(' ')
- written++
- if err != nil {
- return written, err
- }
- ts, err := ptypes.Timestamp((*e).Timestamp)
- if err != nil {
- return written, err
- }
- // TODO(beorn7): Format this directly from components of ts to
- // avoid overflow/underflow and precision issues of the float
- // conversion.
- n, err = writeOpenMetricsFloat(w, float64(ts.UnixNano())/1e9)
- written += n
- if err != nil {
- return written, err
- }
- }
- return written, nil
- }
- // writeOpenMetricsFloat works like writeFloat but appends ".0" if the resulting
- // number would otherwise contain neither a "." nor an "e".
- func writeOpenMetricsFloat(w enhancedWriter, f float64) (int, error) {
- switch {
- case f == 1:
- return w.WriteString("1.0")
- case f == 0:
- return w.WriteString("0.0")
- case f == -1:
- return w.WriteString("-1.0")
- 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, 'g', -1, 64)
- if !bytes.ContainsAny(*bp, "e.") {
- *bp = append(*bp, '.', '0')
- }
- written, err := w.Write(*bp)
- numBufPool.Put(bp)
- return written, err
- }
- }
- // writeUint is like writeInt just for uint64.
- func writeUint(w enhancedWriter, u uint64) (int, error) {
- bp := numBufPool.Get().(*[]byte)
- *bp = strconv.AppendUint((*bp)[:0], u, 10)
- written, err := w.Write(*bp)
- numBufPool.Put(bp)
- return written, err
- }
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