132 lines
4.0 KiB
Go
132 lines
4.0 KiB
Go
// Copyright 2020 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_test
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import (
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"google.golang.org/protobuf/proto"
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dto "github.com/prometheus/client_model/go"
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"github.com/prometheus/client_golang/prometheus"
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)
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// Info implements an info pseudo-metric, which is modeled as a Gauge that
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// always has a value of 1. In practice, you would just use a Gauge directly,
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// but for this example, we pretend it would be useful to have a “native”
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// implementation.
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type Info struct {
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desc *prometheus.Desc
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labelPairs []*dto.LabelPair
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}
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func (i Info) Desc() *prometheus.Desc {
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return i.desc
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}
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func (i Info) Write(out *dto.Metric) error {
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out.Label = i.labelPairs
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out.Gauge = &dto.Gauge{Value: proto.Float64(1)}
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return nil
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}
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// InfoVec is the vector version for Info. As an info metric never changes, we
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// wouldn't really need to wrap GetMetricWithLabelValues and GetMetricWith
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// because Info has no additional methods compared to the vanilla Metric that
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// the unwrapped MetricVec methods return. However, to demonstrate all there is
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// to do to fully implement a vector for a custom Metric implementation, we do
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// it in this example anyway.
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type InfoVec struct {
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*prometheus.MetricVec
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}
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func NewInfoVec(name, help string, labelNames []string) *InfoVec {
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desc := prometheus.NewDesc(name, help, labelNames, nil)
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return &InfoVec{
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MetricVec: prometheus.NewMetricVec(desc, func(lvs ...string) prometheus.Metric {
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if len(lvs) != len(labelNames) {
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panic("inconsistent label cardinality")
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}
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return Info{desc: desc, labelPairs: prometheus.MakeLabelPairs(desc, lvs)}
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}),
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}
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}
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func (v *InfoVec) GetMetricWithLabelValues(lvs ...string) (Info, error) {
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metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
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return metric.(Info), err
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}
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func (v *InfoVec) GetMetricWith(labels prometheus.Labels) (Info, error) {
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metric, err := v.MetricVec.GetMetricWith(labels)
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return metric.(Info), err
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}
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func (v *InfoVec) WithLabelValues(lvs ...string) Info {
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i, err := v.GetMetricWithLabelValues(lvs...)
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if err != nil {
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panic(err)
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}
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return i
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}
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func (v *InfoVec) With(labels prometheus.Labels) Info {
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i, err := v.GetMetricWith(labels)
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if err != nil {
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panic(err)
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}
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return i
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}
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func (v *InfoVec) CurryWith(labels prometheus.Labels) (*InfoVec, error) {
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vec, err := v.MetricVec.CurryWith(labels)
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if vec != nil {
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return &InfoVec{vec}, err
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}
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return nil, err
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}
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func (v *InfoVec) MustCurryWith(labels prometheus.Labels) *InfoVec {
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vec, err := v.CurryWith(labels)
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if err != nil {
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panic(err)
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}
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return vec
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}
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func ExampleMetricVec() {
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infoVec := NewInfoVec(
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"library_version_info",
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"Versions of the libraries used in this binary.",
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[]string{"library", "version"},
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)
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infoVec.WithLabelValues("prometheus/client_golang", "1.7.1")
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infoVec.WithLabelValues("k8s.io/client-go", "0.18.8")
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// Just for demonstration, let's check the state of the InfoVec by
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// registering it with a custom registry and then let it collect the
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// metrics.
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reg := prometheus.NewRegistry()
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reg.MustRegister(infoVec)
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metricFamilies, err := reg.Gather()
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if err != nil || len(metricFamilies) != 1 {
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panic("unexpected behavior of custom test registry")
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}
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printlnNormalized(metricFamilies[0])
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// Output:
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// {"name":"library_version_info","help":"Versions of the libraries used in this binary.","type":"GAUGE","metric":[{"label":[{"name":"library","value":"k8s.io/client-go"},{"name":"version","value":"0.18.8"}],"gauge":{"value":1}},{"label":[{"name":"library","value":"prometheus/client_golang"},{"name":"version","value":"1.7.1"}],"gauge":{"value":1}}]}
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}
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