Source: labels.go in package github.com/prometheus/common/model

Copyright 2013 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 model

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
	"unicode/utf8"
)

AlertNameLabel is the name of the label containing the an alert's name.

	AlertNameLabel = "alertname"

ExportedLabelPrefix is the prefix to prepend to the label names present in exported metrics if a label of the same name is added by the server.

	ExportedLabelPrefix = "exported_"

MetricNameLabel is the label name indicating the metric name of a timeseries.

	MetricNameLabel = "__name__"

SchemeLabel is the name of the label that holds the scheme on which to scrape a target.

	SchemeLabel = "__scheme__"

AddressLabel is the name of the label that holds the address of a scrape target.

	AddressLabel = "__address__"

MetricsPathLabel is the name of the label that holds the path on which to scrape a target.

	MetricsPathLabel = "__metrics_path__"

ReservedLabelPrefix is a prefix which is not legal in user-supplied label names.

	ReservedLabelPrefix = "__"

MetaLabelPrefix is a prefix for labels that provide meta information. Labels with this prefix are used for intermediate label processing and will not be attached to time series.

	MetaLabelPrefix = "__meta_"

TmpLabelPrefix is a prefix for temporary labels as part of relabelling. Labels with this prefix are used for intermediate label processing and will not be attached to time series. This is reserved for use in Prometheus configuration files by users.

	TmpLabelPrefix = "__tmp_"

ParamLabelPrefix is a prefix for labels that provide URL parameters used to scrape a target.

	ParamLabelPrefix = "__param_"

JobLabel is the label name indicating the job from which a timeseries was scraped.

	JobLabel = "job"

InstanceLabel is the label name used for the instance label.

	InstanceLabel = "instance"

BucketLabel is used for the label that defines the upper bound of a bucket of a histogram ("le" -> "less or equal").

	BucketLabel = "le"

QuantileLabel is used for the label that defines the quantile in a summary.

	QuantileLabel = "quantile"
)

LabelNameRE is a regular expression matching valid label names. Note that the IsValid method of LabelName performs the same check but faster than a match with this regular expression.

var LabelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")

A LabelName is a key for a LabelSet or Metric. It has a value associated therewith.

type LabelName string

IsValid is true iff the label name matches the pattern of LabelNameRE. This method, however, does not use LabelNameRE for the check but a much faster hardcoded implementation.

func (ln LabelName) IsValid() bool {
	if len(ln) == 0 {
		return false
	}
	for i, b := range ln {
		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
			return false
		}
	}
	return true
}

UnmarshalYAML implements the yaml.Unmarshaler interface.

func (ln *LabelName) UnmarshalYAML(unmarshal func(interface{}) error) error {
	var s string
	if err := unmarshal(&s); err != nil {
		return err
	}
	if !LabelName(s).IsValid() {
		return fmt.Errorf("%q is not a valid label name", s)
	}
	*ln = LabelName(s)
	return nil
}

UnmarshalJSON implements the json.Unmarshaler interface.

func (ln *LabelName) UnmarshalJSON(b []byte) error {
	var s string
	if err := json.Unmarshal(b, &s); err != nil {
		return err
	}
	if !LabelName(s).IsValid() {
		return fmt.Errorf("%q is not a valid label name", s)
	}
	*ln = LabelName(s)
	return nil
}

LabelNames is a sortable LabelName slice. In implements sort.Interface.

type LabelNames []LabelName

func (l LabelNames) Len() int {
	return len(l)
}

func (l LabelNames) Less(i, j int) bool {
	return l[i] < l[j]
}

func (l LabelNames) Swap(i, j int) {
	l[i], l[j] = l[j], l[i]
}

func (l LabelNames) String() string {
	labelStrings := make([]string, 0, len(l))
	for _, label := range l {
		labelStrings = append(labelStrings, string(label))
	}
	return strings.Join(labelStrings, ", ")
}

A LabelValue is an associated value for a LabelName.

type LabelValue string

IsValid returns true iff the string is a valid UTF8.

func (lv LabelValue) IsValid() bool {
	return utf8.ValidString(string(lv))
}

LabelValues is a sortable LabelValue slice. It implements sort.Interface.

type LabelValues []LabelValue

func (l LabelValues) Len() int {
	return len(l)
}

func (l LabelValues) Less(i, j int) bool {
	return string(l[i]) < string(l[j])
}

func (l LabelValues) Swap(i, j int) {
	l[i], l[j] = l[j], l[i]
}

LabelPair pairs a name with a value.

type LabelPair struct {
	Name  LabelName
	Value LabelValue
}

LabelPairs is a sortable slice of LabelPair pointers. It implements sort.Interface.

type LabelPairs []*LabelPair

func (l LabelPairs) Len() int {
	return len(l)
}

func (l LabelPairs) Less(i, j int) bool {
	switch {
	case l[i].Name > l[j].Name:
		return false
	case l[i].Name < l[j].Name:
		return true
	case l[i].Value > l[j].Value:
		return false
	case l[i].Value < l[j].Value:
		return true
	default:
		return false
	}
}

func (l LabelPairs) Swap(i, j int) {
	l[i], l[j] = l[j], l[i]