2019-05-31 09:45:11 +00:00
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// Copyright 2018 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package prometheus
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import (
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"errors"
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"fmt"
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"strings"
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"unicode/utf8"
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"github.com/prometheus/common/model"
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)
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// Labels represents a collection of label name -> value mappings. This type is
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// commonly used with the With(Labels) and GetMetricWith(Labels) methods of
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// metric vector Collectors, e.g.:
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//
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// myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
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//
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// The other use-case is the specification of constant label pairs in Opts or to
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// create a Desc.
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type Labels map[string]string
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2023-05-03 14:53:36 +00:00
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// ConstrainedLabels represents a label name and its constrain function
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// to normalize label values. This type is commonly used when constructing
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// metric vector Collectors.
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type ConstrainedLabel struct {
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Name string
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Constraint func(string) string
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}
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func (cl ConstrainedLabel) Constrain(v string) string {
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if cl.Constraint == nil {
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return v
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}
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return cl.Constraint(v)
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}
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// ConstrainableLabels is an interface that allows creating of labels that can
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// be optionally constrained.
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//
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// prometheus.V2().NewCounterVec(CounterVecOpts{
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// CounterOpts: {...}, // Usual CounterOpts fields
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// VariableLabels: []ConstrainedLabels{
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// {Name: "A"},
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// {Name: "B", Constraint: func(v string) string { ... }},
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// },
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// })
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type ConstrainableLabels interface {
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constrainedLabels() ConstrainedLabels
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labelNames() []string
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}
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// ConstrainedLabels represents a collection of label name -> constrain function
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// to normalize label values. This type is commonly used when constructing
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// metric vector Collectors.
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type ConstrainedLabels []ConstrainedLabel
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func (cls ConstrainedLabels) constrainedLabels() ConstrainedLabels {
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return cls
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}
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func (cls ConstrainedLabels) labelNames() []string {
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names := make([]string, len(cls))
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for i, label := range cls {
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names[i] = label.Name
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}
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return names
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}
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// UnconstrainedLabels represents collection of label without any constraint on
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// their value. Thus, it is simply a collection of label names.
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//
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// UnconstrainedLabels([]string{ "A", "B" })
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//
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// is equivalent to
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//
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// ConstrainedLabels {
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// { Name: "A" },
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// { Name: "B" },
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// }
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type UnconstrainedLabels []string
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func (uls UnconstrainedLabels) constrainedLabels() ConstrainedLabels {
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constrainedLabels := make([]ConstrainedLabel, len(uls))
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for i, l := range uls {
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constrainedLabels[i] = ConstrainedLabel{Name: l}
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}
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return constrainedLabels
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}
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func (uls UnconstrainedLabels) labelNames() []string {
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return uls
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}
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2019-05-31 09:45:11 +00:00
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// reservedLabelPrefix is a prefix which is not legal in user-supplied
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// label names.
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const reservedLabelPrefix = "__"
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var errInconsistentCardinality = errors.New("inconsistent label cardinality")
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func makeInconsistentCardinalityError(fqName string, labels, labelValues []string) error {
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return fmt.Errorf(
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"%w: %q has %d variable labels named %q but %d values %q were provided",
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2019-05-31 09:45:11 +00:00
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errInconsistentCardinality, fqName,
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len(labels), labels,
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len(labelValues), labelValues,
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)
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}
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func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
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if len(labels) != expectedNumberOfValues {
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return fmt.Errorf(
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2022-11-28 20:03:09 +00:00
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"%w: expected %d label values but got %d in %#v",
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2019-05-31 09:45:11 +00:00
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errInconsistentCardinality, expectedNumberOfValues,
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len(labels), labels,
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)
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}
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for name, val := range labels {
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if !utf8.ValidString(val) {
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return fmt.Errorf("label %s: value %q is not valid UTF-8", name, val)
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}
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}
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return nil
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}
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func validateLabelValues(vals []string, expectedNumberOfValues int) error {
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if len(vals) != expectedNumberOfValues {
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return fmt.Errorf(
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2022-11-28 20:03:09 +00:00
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"%w: expected %d label values but got %d in %#v",
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2019-05-31 09:45:11 +00:00
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errInconsistentCardinality, expectedNumberOfValues,
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len(vals), vals,
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)
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}
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for _, val := range vals {
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if !utf8.ValidString(val) {
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return fmt.Errorf("label value %q is not valid UTF-8", val)
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}
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}
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return nil
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}
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func checkLabelName(l string) bool {
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return model.LabelName(l).IsValid() && !strings.HasPrefix(l, reservedLabelPrefix)
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}
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