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Merge pull request #803 from prometheus/beorn7/vec
Export MetricVec (again)
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| Original file line number | Diff line number | Diff line change |
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| // Copyright 2020 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. | ||
|
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| package prometheus_test | ||
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| import ( | ||
| //lint:ignore SA1019 Need to keep deprecated package for compatibility. | ||
| "fmt" | ||
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| "github.com/golang/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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| // Info implements an info pseudo-metric, which is modeled as a Gauge that | ||
| // always has a value of 1. In practice, you would just use a Gauge directly, | ||
| // but for this example, we pretend it would be useful to have a “native” | ||
| // implementation. | ||
| type Info struct { | ||
| desc *prometheus.Desc | ||
| labelPairs []*dto.LabelPair | ||
| } | ||
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| func (i Info) Desc() *prometheus.Desc { | ||
| return i.desc | ||
| } | ||
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| func (i Info) Write(out *dto.Metric) error { | ||
| out.Label = i.labelPairs | ||
| out.Gauge = &dto.Gauge{Value: proto.Float64(1)} | ||
| return nil | ||
| } | ||
|
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| // InfoVec is the vector version for Info. As an info metric never changes, we | ||
| // wouldn't really need to wrap GetMetricWithLabelValues and GetMetricWith | ||
| // because Info has no additional methods compared to the vanilla Metric that | ||
| // the unwrapped MetricVec methods return. However, to demonstrate all there is | ||
| // to do to fully implement a vector for a custom Metric implementation, we do | ||
| // it in this example anyway. | ||
| type InfoVec struct { | ||
| *prometheus.MetricVec | ||
| } | ||
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| func NewInfoVec(name, help string, labelNames []string) *InfoVec { | ||
| desc := prometheus.NewDesc(name, help, labelNames, nil) | ||
| return &InfoVec{ | ||
| MetricVec: prometheus.NewMetricVec(desc, func(lvs ...string) prometheus.Metric { | ||
| if len(lvs) != len(labelNames) { | ||
| panic("inconsistent label cardinality") | ||
| } | ||
| return Info{desc: desc, labelPairs: prometheus.MakeLabelPairs(desc, lvs)} | ||
| }), | ||
| } | ||
| } | ||
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| func (v *InfoVec) GetMetricWithLabelValues(lvs ...string) (Info, error) { | ||
| metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...) | ||
| return metric.(Info), err | ||
| } | ||
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| func (v *InfoVec) GetMetricWith(labels prometheus.Labels) (Info, error) { | ||
| metric, err := v.MetricVec.GetMetricWith(labels) | ||
| return metric.(Info), err | ||
| } | ||
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| func (v *InfoVec) WithLabelValues(lvs ...string) Info { | ||
| i, err := v.GetMetricWithLabelValues(lvs...) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| return i | ||
| } | ||
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| func (v *InfoVec) With(labels prometheus.Labels) Info { | ||
| i, err := v.GetMetricWith(labels) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| return i | ||
| } | ||
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| func (v *InfoVec) CurryWith(labels prometheus.Labels) (*InfoVec, error) { | ||
| vec, err := v.MetricVec.CurryWith(labels) | ||
| if vec != nil { | ||
| return &InfoVec{vec}, err | ||
| } | ||
| return nil, err | ||
| } | ||
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| func (v *InfoVec) MustCurryWith(labels prometheus.Labels) *InfoVec { | ||
| vec, err := v.CurryWith(labels) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| return vec | ||
| } | ||
|
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| func ExampleMetricVec() { | ||
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| infoVec := NewInfoVec( | ||
| "library_version_info", | ||
| "Versions of the libraries used in this binary.", | ||
| []string{"library", "version"}, | ||
| ) | ||
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| infoVec.WithLabelValues("prometheus/client_golang", "1.7.1") | ||
| 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 | ||
| // registering it with a custom registry and then let it collect the | ||
| // metrics. | ||
| reg := prometheus.NewRegistry() | ||
| reg.MustRegister(infoVec) | ||
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| metricFamilies, err := reg.Gather() | ||
| if err != nil || len(metricFamilies) != 1 { | ||
| panic("unexpected behavior of custom test registry") | ||
| } | ||
| fmt.Println(proto.MarshalTextString(metricFamilies[0])) | ||
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| // Output: | ||
| // name: "library_version_info" | ||
| // help: "Versions of the libraries used in this binary." | ||
| // type: GAUGE | ||
| // metric: < | ||
| // label: < | ||
| // name: "library" | ||
| // value: "k8s.io/client-go" | ||
| // > | ||
| // label: < | ||
| // name: "version" | ||
| // value: "0.18.8" | ||
| // > | ||
| // gauge: < | ||
| // value: 1 | ||
| // > | ||
| // > | ||
| // metric: < | ||
| // label: < | ||
| // name: "library" | ||
| // value: "prometheus/client_golang" | ||
| // > | ||
| // label: < | ||
| // name: "version" | ||
| // value: "1.7.1" | ||
| // > | ||
| // gauge: < | ||
| // value: 1 | ||
| // > | ||
| // > | ||
| } |
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