prometheus/model/textparse/interface.go
beorn7 9e500345f3 textparse/scrape: Add option to scrape both classic and native histograms
So far, if a target exposes a histogram with both classic and native
buckets, a native-histogram enabled Prometheus would ignore the
classic buckets. With the new scrape config option
`scrape_classic_histograms` set, both buckets will be ingested,
creating all the series of a classic histogram in parallel to the
native histogram series. For example, a histogram `foo` would create a
native histogram series `foo` and classic series called `foo_sum`,
`foo_count`, and `foo_bucket`.

This feature can be used in a migration strategy from classic to
native histograms, where it is desired to have a transition period
during which both native and classic histograms are present.

Note that two bugs in classic histogram parsing were found and fixed
as a byproduct of testing the new feature:

1. Series created from classic _gauge_ histograms didn't get the
   _sum/_count/_bucket prefix set.
2. Values of classic _float_ histograms weren't parsed properly.

Signed-off-by: beorn7 <beorn@grafana.com>
2023-05-13 01:32:25 +02:00

119 lines
4.3 KiB
Go

// Copyright 2018 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 textparse
import (
"mime"
"github.com/prometheus/prometheus/model/exemplar"
"github.com/prometheus/prometheus/model/histogram"
"github.com/prometheus/prometheus/model/labels"
)
// Parser parses samples from a byte slice of samples in the official
// Prometheus and OpenMetrics text exposition formats.
type Parser interface {
// Series returns the bytes of a series with a simple float64 as a
// value, the timestamp if set, and the value of the current sample.
Series() ([]byte, *int64, float64)
// Histogram returns the bytes of a series with a sparse histogram as a
// value, the timestamp if set, and the histogram in the current sample.
// Depending on the parsed input, the function returns an (integer) Histogram
// or a FloatHistogram, with the respective other return value being nil.
Histogram() ([]byte, *int64, *histogram.Histogram, *histogram.FloatHistogram)
// Help returns the metric name and help text in the current entry.
// Must only be called after Next returned a help entry.
// The returned byte slices become invalid after the next call to Next.
Help() ([]byte, []byte)
// Type returns the metric name and type in the current entry.
// Must only be called after Next returned a type entry.
// The returned byte slices become invalid after the next call to Next.
Type() ([]byte, MetricType)
// Unit returns the metric name and unit in the current entry.
// Must only be called after Next returned a unit entry.
// The returned byte slices become invalid after the next call to Next.
Unit() ([]byte, []byte)
// Comment returns the text of the current comment.
// Must only be called after Next returned a comment entry.
// The returned byte slice becomes invalid after the next call to Next.
Comment() []byte
// Metric writes the labels of the current sample into the passed labels.
// It returns the string from which the metric was parsed.
Metric(l *labels.Labels) string
// Exemplar writes the exemplar of the current sample into the passed
// exemplar. It returns if an exemplar exists or not.
Exemplar(l *exemplar.Exemplar) bool
// Next advances the parser to the next sample. It returns false if no
// more samples were read or an error occurred.
Next() (Entry, error)
}
// New returns a new parser of the byte slice.
//
// This function always returns a valid parser, but might additionally
// return an error if the content type cannot be parsed.
func New(b []byte, contentType string, parseClassicHistograms bool) (Parser, error) {
if contentType == "" {
return NewPromParser(b), nil
}
mediaType, _, err := mime.ParseMediaType(contentType)
if err != nil {
return NewPromParser(b), err
}
switch mediaType {
case "application/openmetrics-text":
return NewOpenMetricsParser(b), nil
case "application/vnd.google.protobuf":
return NewProtobufParser(b, parseClassicHistograms), nil
default:
return NewPromParser(b), nil
}
}
// Entry represents the type of a parsed entry.
type Entry int
const (
EntryInvalid Entry = -1
EntryType Entry = 0
EntryHelp Entry = 1
EntrySeries Entry = 2 // A series with a simple float64 as value.
EntryComment Entry = 3
EntryUnit Entry = 4
EntryHistogram Entry = 5 // A series with a native histogram as a value.
)
// MetricType represents metric type values.
type MetricType string
const (
MetricTypeCounter = MetricType("counter")
MetricTypeGauge = MetricType("gauge")
MetricTypeHistogram = MetricType("histogram")
MetricTypeGaugeHistogram = MetricType("gaugehistogram")
MetricTypeSummary = MetricType("summary")
MetricTypeInfo = MetricType("info")
MetricTypeStateset = MetricType("stateset")
MetricTypeUnknown = MetricType("unknown")
)