/
metadata.go
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/
metadata.go
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// Copyright 2019, OpenTelemetry 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 internal
import (
"errors"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/pkg/labels"
"github.com/prometheus/prometheus/scrape"
)
// MetadataService is an adapter to scrapeManager and provide only the functionality which is needed
type MetadataService interface {
Get(job, instance string) (MetadataCache, error)
}
// MetadataCache is an adapter to prometheus' scrape.Target and provide only the functionality which is needed
type MetadataCache interface {
Metadata(metricName string) (scrape.MetricMetadata, bool)
SharedLabels() labels.Labels
}
type mService struct {
sm *scrape.Manager
}
func (t *mService) Get(job, instance string) (MetadataCache, error) {
targetGroup, ok := t.sm.TargetsAll()[job]
if !ok {
return nil, errors.New("unable to find a target group with job=" + job)
}
// from the same targetGroup, instance is not going to be duplicated
for _, target := range targetGroup {
if target.DiscoveredLabels().Get(model.AddressLabel) == instance {
return &mCache{target}, nil
}
}
return nil, errors.New("unable to find a target with job=" + job + ", and instance=" + instance)
}
// adapter to get metadata from scrape.Target
type mCache struct {
t *scrape.Target
}
func (m *mCache) Metadata(metricName string) (scrape.MetricMetadata, bool) {
return m.t.Metadata(metricName)
}
func (m *mCache) SharedLabels() labels.Labels {
return m.t.DiscoveredLabels()
}