VictoriaMetrics/vendor/github.com/prometheus/common/expfmt/expfmt.go
2024-03-01 00:55:54 +02:00

167 lines
5 KiB
Go

// Copyright 2015 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 contains tools for reading and writing Prometheus metrics.
package expfmt
import (
"strings"
"github.com/prometheus/common/model"
)
// Format specifies the HTTP content type of the different wire protocols.
type Format string
// Constants to assemble the Content-Type values for the different wire
// protocols. The Content-Type strings here are all for the legacy exposition
// formats, where valid characters for metric names and label names are limited.
// Support for arbitrary UTF-8 characters in those names is already partially
// implemented in this module (see model.ValidationScheme), but to actually use
// it on the wire, new content-type strings will have to be agreed upon and
// added here.
const (
TextVersion = "0.0.4"
ProtoType = `application/vnd.google.protobuf`
ProtoProtocol = `io.prometheus.client.MetricFamily`
protoFmt = ProtoType + "; proto=" + ProtoProtocol + ";"
OpenMetricsType = `application/openmetrics-text`
OpenMetricsVersion_0_0_1 = "0.0.1"
OpenMetricsVersion_1_0_0 = "1.0.0"
// The Content-Type values for the different wire protocols. Note that these
// values are now unexported. If code was relying on comparisons to these
// constants, instead use FormatType().
fmtUnknown Format = `<unknown>`
fmtText Format = `text/plain; version=` + TextVersion + `; charset=utf-8`
fmtProtoDelim Format = protoFmt + ` encoding=delimited`
fmtProtoText Format = protoFmt + ` encoding=text`
fmtProtoCompact Format = protoFmt + ` encoding=compact-text`
fmtOpenMetrics_1_0_0 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_1_0_0 + `; charset=utf-8`
fmtOpenMetrics_0_0_1 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_0_0_1 + `; charset=utf-8`
)
const (
hdrContentType = "Content-Type"
hdrAccept = "Accept"
)
// FormatType is a Go enum representing the overall category for the given
// Format. As the number of Format permutations increases, doing basic string
// comparisons are not feasible, so this enum captures the most useful
// high-level attribute of the Format string.
type FormatType int
const (
TypeUnknown = iota
TypeProtoCompact
TypeProtoDelim
TypeProtoText
TypeTextPlain
TypeOpenMetrics
)
// NewFormat generates a new Format from the type provided. Mostly used for
// tests, most Formats should be generated as part of content negotiation in
// encode.go.
func NewFormat(t FormatType) Format {
switch t {
case TypeProtoCompact:
return fmtProtoCompact
case TypeProtoDelim:
return fmtProtoDelim
case TypeProtoText:
return fmtProtoText
case TypeTextPlain:
return fmtText
case TypeOpenMetrics:
return fmtOpenMetrics_1_0_0
default:
return fmtUnknown
}
}
// FormatType deduces an overall FormatType for the given format.
func (f Format) FormatType() FormatType {
toks := strings.Split(string(f), ";")
if len(toks) < 2 {
return TypeUnknown
}
params := make(map[string]string)
for i, t := range toks {
if i == 0 {
continue
}
args := strings.Split(t, "=")
if len(args) != 2 {
continue
}
params[strings.TrimSpace(args[0])] = strings.TrimSpace(args[1])
}
switch strings.TrimSpace(toks[0]) {
case ProtoType:
if params["proto"] != ProtoProtocol {
return TypeUnknown
}
switch params["encoding"] {
case "delimited":
return TypeProtoDelim
case "text":
return TypeProtoText
case "compact-text":
return TypeProtoCompact
default:
return TypeUnknown
}
case OpenMetricsType:
if params["charset"] != "utf-8" {
return TypeUnknown
}
return TypeOpenMetrics
case "text/plain":
v, ok := params["version"]
if !ok {
return TypeTextPlain
}
if v == TextVersion {
return TypeTextPlain
}
return TypeUnknown
default:
return TypeUnknown
}
}
// ToEscapingScheme returns an EscapingScheme depending on the Format. Iff the
// Format contains a escaping=allow-utf-8 term, it will select NoEscaping. If a valid
// "escaping" term exists, that will be used. Otherwise, the global default will
// be returned.
func (format Format) ToEscapingScheme() model.EscapingScheme {
for _, p := range strings.Split(string(format), ";") {
toks := strings.Split(p, "=")
if len(toks) != 2 {
continue
}
key, value := strings.TrimSpace(toks[0]), strings.TrimSpace(toks[1])
if key == model.EscapingKey {
scheme, err := model.ToEscapingScheme(value)
if err != nil {
return model.NameEscapingScheme
}
return scheme
}
}
return model.NameEscapingScheme
}