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scrape.go
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scrape.go
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// Adapted by Miek Gieben for CoreDNS testing.
//
// License from prom2json
// Copyright 2014 Prometheus Team
// 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 test will scrape a target and you can inspect the variables.
// Basic usage:
//
// result := Scrape("http://localhost:9153/metrics")
// v := MetricValue("coredns_cache_capacity", result)
//
package test
import (
"fmt"
"io"
"mime"
"net/http"
"testing"
"github.com/matttproud/golang_protobuf_extensions/pbutil"
"github.com/prometheus/common/expfmt"
dto "github.com/prometheus/client_model/go"
)
type (
// MetricFamily holds a prometheus metric.
MetricFamily struct {
Name string `json:"name"`
Help string `json:"help"`
Type string `json:"type"`
Metrics []interface{} `json:"metrics,omitempty"` // Either metric or summary.
}
// metric is for all "single value" metrics.
metric struct {
Labels map[string]string `json:"labels,omitempty"`
Value string `json:"value"`
}
summary struct {
Labels map[string]string `json:"labels,omitempty"`
Quantiles map[string]string `json:"quantiles,omitempty"`
Count string `json:"count"`
Sum string `json:"sum"`
}
histogram struct {
Labels map[string]string `json:"labels,omitempty"`
Buckets map[string]string `json:"buckets,omitempty"`
Count string `json:"count"`
Sum string `json:"sum"`
}
)
// Scrape returns the all the vars a []*metricFamily.
func Scrape(t *testing.T, url string) []*MetricFamily {
mfChan := make(chan *dto.MetricFamily, 1024)
go fetchMetricFamilies(t, url, mfChan)
result := []*MetricFamily{}
for mf := range mfChan {
result = append(result, newMetricFamily(mf))
}
return result
}
// MetricValue returns the value associated with name as a string as well as the labels.
// It only returns the first metrics of the slice.
func MetricValue(name string, mfs []*MetricFamily) (string, map[string]string) {
for _, mf := range mfs {
if mf.Name == name {
// Only works with Gauge and Counter...
return mf.Metrics[0].(metric).Value, mf.Metrics[0].(metric).Labels
}
}
return "", nil
}
// MetricValueLabel returns the value for name *and* label *value*.
func MetricValueLabel(name, label string, mfs []*MetricFamily) (string, map[string]string) {
// bit hacky is this really handy...?
for _, mf := range mfs {
if mf.Name == name {
for _, m := range mf.Metrics {
for _, v := range m.(metric).Labels {
if v == label {
return m.(metric).Value, m.(metric).Labels
}
}
}
}
}
return "", nil
}
func newMetricFamily(dtoMF *dto.MetricFamily) *MetricFamily {
mf := &MetricFamily{
Name: dtoMF.GetName(),
Help: dtoMF.GetHelp(),
Type: dtoMF.GetType().String(),
Metrics: make([]interface{}, len(dtoMF.Metric)),
}
for i, m := range dtoMF.Metric {
if dtoMF.GetType() == dto.MetricType_SUMMARY {
mf.Metrics[i] = summary{
Labels: makeLabels(m),
Quantiles: makeQuantiles(m),
Count: fmt.Sprint(m.GetSummary().GetSampleCount()),
Sum: fmt.Sprint(m.GetSummary().GetSampleSum()),
}
} else if dtoMF.GetType() == dto.MetricType_HISTOGRAM {
mf.Metrics[i] = histogram{
Labels: makeLabels(m),
Buckets: makeBuckets(m),
Count: fmt.Sprint(m.GetHistogram().GetSampleCount()),
Sum: fmt.Sprint(m.GetSummary().GetSampleSum()),
}
} else {
mf.Metrics[i] = metric{
Labels: makeLabels(m),
Value: fmt.Sprint(value(m)),
}
}
}
return mf
}
func value(m *dto.Metric) float64 {
if m.Gauge != nil {
return m.GetGauge().GetValue()
}
if m.Counter != nil {
return m.GetCounter().GetValue()
}
if m.Untyped != nil {
return m.GetUntyped().GetValue()
}
return 0.
}
func makeLabels(m *dto.Metric) map[string]string {
result := map[string]string{}
for _, lp := range m.Label {
result[lp.GetName()] = lp.GetValue()
}
return result
}
func makeQuantiles(m *dto.Metric) map[string]string {
result := map[string]string{}
for _, q := range m.GetSummary().Quantile {
result[fmt.Sprint(q.GetQuantile())] = fmt.Sprint(q.GetValue())
}
return result
}
func makeBuckets(m *dto.Metric) map[string]string {
result := map[string]string{}
for _, b := range m.GetHistogram().Bucket {
result[fmt.Sprint(b.GetUpperBound())] = fmt.Sprint(b.GetCumulativeCount())
}
return result
}
func fetchMetricFamilies(t *testing.T, url string, ch chan<- *dto.MetricFamily) {
defer close(ch)
req, err := http.NewRequest("GET", url, nil)
if err != nil {
t.Fatalf("creating GET request for URL %q failed: %s", url, err)
}
req.Header.Add("Accept", acceptHeader)
resp, err := http.DefaultClient.Do(req)
if err != nil {
t.Fatalf("executing GET request for URL %q failed: %s", url, err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
t.Fatalf("GET request for URL %q returned HTTP status %s", url, resp.Status)
}
mediatype, params, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
if err == nil && mediatype == "application/vnd.google.protobuf" &&
params["encoding"] == "delimited" &&
params["proto"] == "io.prometheus.client.MetricFamily" {
for {
mf := &dto.MetricFamily{}
if _, err = pbutil.ReadDelimited(resp.Body, mf); err != nil {
if err == io.EOF {
break
}
t.Fatalf("reading metric family protocol buffer failed: %s", err)
}
ch <- mf
}
} else {
// We could do further content-type checks here, but the
// fallback for now will anyway be the text format
// version 0.0.4, so just go for it and see if it works.
var parser expfmt.TextParser
metricFamilies, err := parser.TextToMetricFamilies(resp.Body)
if err != nil {
t.Fatal("reading text format failed:", err)
}
for _, mf := range metricFamilies {
ch <- mf
}
}
}
const acceptHeader = `application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.7,text/plain;version=0.0.4;q=0.3`