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relabel.go
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relabel.go
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// Copyright 2015 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 relabel
import (
"crypto/md5"
"fmt"
"strings"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/pkg/labels"
)
// Process returns a relabeled copy of the given label set. The relabel configurations
// are applied in order of input.
// If a label set is dropped, nil is returned.
// May return the input labelSet modified.
func Process(labels labels.Labels, cfgs ...*config.RelabelConfig) labels.Labels {
for _, cfg := range cfgs {
labels = relabel(labels, cfg)
if labels == nil {
return nil
}
}
return labels
}
func relabel(lset labels.Labels, cfg *config.RelabelConfig) labels.Labels {
values := make([]string, 0, len(cfg.SourceLabels))
for _, ln := range cfg.SourceLabels {
values = append(values, lset.Get(string(ln)))
}
val := strings.Join(values, cfg.Separator)
lb := labels.NewBuilder(lset)
switch cfg.Action {
case config.RelabelDrop:
if cfg.Regex.MatchString(val) {
return nil
}
case config.RelabelKeep:
if !cfg.Regex.MatchString(val) {
return nil
}
case config.RelabelReplace:
indexes := cfg.Regex.FindStringSubmatchIndex(val)
// If there is no match no replacement must take place.
if indexes == nil {
break
}
target := model.LabelName(cfg.Regex.ExpandString([]byte{}, cfg.TargetLabel, val, indexes))
if !target.IsValid() {
lb.Del(cfg.TargetLabel)
break
}
res := cfg.Regex.ExpandString([]byte{}, cfg.Replacement, val, indexes)
if len(res) == 0 {
lb.Del(cfg.TargetLabel)
break
}
lb.Set(string(target), string(res))
case config.RelabelHashMod:
mod := sum64(md5.Sum([]byte(val))) % cfg.Modulus
lb.Set(cfg.TargetLabel, fmt.Sprintf("%d", mod))
case config.RelabelLabelMap:
for _, l := range lset {
if cfg.Regex.MatchString(l.Name) {
res := cfg.Regex.ReplaceAllString(l.Name, cfg.Replacement)
lb.Set(res, l.Value)
}
}
case config.RelabelLabelDrop:
for _, l := range lset {
if cfg.Regex.MatchString(l.Name) {
lb.Del(l.Name)
}
}
case config.RelabelLabelKeep:
for _, l := range lset {
if !cfg.Regex.MatchString(l.Name) {
lb.Del(l.Name)
}
}
default:
panic(fmt.Errorf("relabel: unknown relabel action type %q", cfg.Action))
}
return lb.Labels()
}
// sum64 sums the md5 hash to an uint64.
func sum64(hash [md5.Size]byte) uint64 {
var s uint64
for i, b := range hash {
shift := uint64((md5.Size - i - 1) * 8)
s |= uint64(b) << shift
}
return s
}