client_golang/prometheus/testutil/testutil.go

157 lines
4.5 KiB
Go

// Copyright 2018 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 testutil
import (
"bytes"
"fmt"
"reflect"
"sort"
"github.com/prometheus/client_golang/prometheus"
dto "github.com/prometheus/client_model/go"
"github.com/prometheus/common/expfmt"
)
// GatherAndCompare retrieves all metrics exposed by a collector and compares it
// to an expected output in the Prometheus text exposition format.
// metricNames allows only comparing the given metrics. All are compared if it's nil.
func GatherAndCompare(c prometheus.Collector, expected string, metricNames ...string) error {
reg := prometheus.NewPedanticRegistry()
if err := reg.Register(c); err != nil {
return fmt.Errorf("registering collector failed: %s", err)
}
metrics, err := reg.Gather()
if err != nil {
return fmt.Errorf("gathering metrics failed: %s", err)
}
if metricNames != nil {
metrics = filterMetrics(metrics, metricNames)
}
var tp expfmt.TextParser
expectedMetrics, err := tp.TextToMetricFamilies(bytes.NewReader([]byte(expected)))
if err != nil {
return fmt.Errorf("parsing expected metrics failed: %s", err)
}
if !reflect.DeepEqual(metrics, normalizeMetricFamilies(expectedMetrics)) {
// Encode the gathered output to the readbale text format for comparison.
var buf1 bytes.Buffer
enc := expfmt.NewEncoder(&buf1, expfmt.FmtText)
for _, mf := range metrics {
if err := enc.Encode(mf); err != nil {
return fmt.Errorf("encoding result failed: %s", err)
}
}
// Encode normalized expected metrics again to generate them in the same ordering
// the registry does to spot differences more easily.
var buf2 bytes.Buffer
enc = expfmt.NewEncoder(&buf2, expfmt.FmtText)
for _, mf := range normalizeMetricFamilies(expectedMetrics) {
if err := enc.Encode(mf); err != nil {
return fmt.Errorf("encoding result failed: %s", err)
}
}
return fmt.Errorf(`
metric output does not match expectation; want:
%s
got:
%s
`, buf2.String(), buf1.String())
}
return nil
}
func filterMetrics(metrics []*dto.MetricFamily, names []string) []*dto.MetricFamily {
var filtered []*dto.MetricFamily
for _, m := range metrics {
drop := true
for _, name := range names {
if m.GetName() == name {
drop = false
break
}
}
if !drop {
filtered = append(filtered, m)
}
}
return filtered
}
// The below sorting code is copied form the Prometheus client library modulo the added
// label pair sorting.
// https://github.com/prometheus/client_golang/blob/ea6e1db4cb8127eeb0b6954f7320363e5451820f/prometheus/registry.go#L642-L684
// metricSorter is a sortable slice of *dto.Metric.
type metricSorter []*dto.Metric
func (s metricSorter) Len() int {
return len(s)
}
func (s metricSorter) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
func (s metricSorter) Less(i, j int) bool {
sort.Sort(prometheus.LabelPairSorter(s[i].Label))
sort.Sort(prometheus.LabelPairSorter(s[j].Label))
if len(s[i].Label) != len(s[j].Label) {
return len(s[i].Label) < len(s[j].Label)
}
for n, lp := range s[i].Label {
vi := lp.GetValue()
vj := s[j].Label[n].GetValue()
if vi != vj {
return vi < vj
}
}
if s[i].TimestampMs == nil {
return false
}
if s[j].TimestampMs == nil {
return true
}
return s[i].GetTimestampMs() < s[j].GetTimestampMs()
}
// normalizeMetricFamilies returns a MetricFamily slice with empty
// MetricFamilies pruned and the remaining MetricFamilies sorted by name within
// the slice, with the contained Metrics sorted within each MetricFamily.
func normalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
for _, mf := range metricFamiliesByName {
sort.Sort(metricSorter(mf.Metric))
}
names := make([]string, 0, len(metricFamiliesByName))
for name, mf := range metricFamiliesByName {
if len(mf.Metric) > 0 {
names = append(names, name)
}
}
sort.Strings(names)
result := make([]*dto.MetricFamily, 0, len(names))
for _, name := range names {
result = append(result, metricFamiliesByName[name])
}
return result
}