prometheus/pkg/relabel/relabel.go

271 lines
7.8 KiB
Go

// 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"
"regexp"
"strings"
"github.com/pkg/errors"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/pkg/labels"
)
var (
relabelTarget = regexp.MustCompile(`^(?:(?:[a-zA-Z_]|\$(?:\{\w+\}|\w+))+\w*)+$`)
DefaultRelabelConfig = Config{
Action: Replace,
Separator: ";",
Regex: MustNewRegexp("(.*)"),
Replacement: "$1",
}
)
// Action is the action to be performed on relabeling.
type Action string
const (
// Replace performs a regex replacement.
Replace Action = "replace"
// Keep drops targets for which the input does not match the regex.
Keep Action = "keep"
// Drop drops targets for which the input does match the regex.
Drop Action = "drop"
// HashMod sets a label to the modulus of a hash of labels.
HashMod Action = "hashmod"
// LabelMap copies labels to other labelnames based on a regex.
LabelMap Action = "labelmap"
// LabelDrop drops any label matching the regex.
LabelDrop Action = "labeldrop"
// LabelKeep drops any label not matching the regex.
LabelKeep Action = "labelkeep"
)
// UnmarshalYAML implements the yaml.Unmarshaler interface.
func (a *Action) UnmarshalYAML(unmarshal func(interface{}) error) error {
var s string
if err := unmarshal(&s); err != nil {
return err
}
switch act := Action(strings.ToLower(s)); act {
case Replace, Keep, Drop, HashMod, LabelMap, LabelDrop, LabelKeep:
*a = act
return nil
}
return errors.Errorf("unknown relabel action %q", s)
}
// Config is the configuration for relabeling of target label sets.
type Config struct {
// A list of labels from which values are taken and concatenated
// with the configured separator in order.
SourceLabels model.LabelNames `yaml:"source_labels,flow,omitempty"`
// Separator is the string between concatenated values from the source labels.
Separator string `yaml:"separator,omitempty"`
// Regex against which the concatenation is matched.
Regex Regexp `yaml:"regex,omitempty"`
// Modulus to take of the hash of concatenated values from the source labels.
Modulus uint64 `yaml:"modulus,omitempty"`
// TargetLabel is the label to which the resulting string is written in a replacement.
// Regexp interpolation is allowed for the replace action.
TargetLabel string `yaml:"target_label,omitempty"`
// Replacement is the regex replacement pattern to be used.
Replacement string `yaml:"replacement,omitempty"`
// Action is the action to be performed for the relabeling.
Action Action `yaml:"action,omitempty"`
}
// UnmarshalYAML implements the yaml.Unmarshaler interface.
func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
*c = DefaultRelabelConfig
type plain Config
if err := unmarshal((*plain)(c)); err != nil {
return err
}
if c.Regex.Regexp == nil {
c.Regex = MustNewRegexp("")
}
if c.Action == "" {
return errors.Errorf("relabel action cannot be empty")
}
if c.Modulus == 0 && c.Action == HashMod {
return errors.Errorf("relabel configuration for hashmod requires non-zero modulus")
}
if (c.Action == Replace || c.Action == HashMod) && c.TargetLabel == "" {
return errors.Errorf("relabel configuration for %s action requires 'target_label' value", c.Action)
}
if c.Action == Replace && !relabelTarget.MatchString(c.TargetLabel) {
return errors.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
}
if c.Action == LabelMap && !relabelTarget.MatchString(c.Replacement) {
return errors.Errorf("%q is invalid 'replacement' for %s action", c.Replacement, c.Action)
}
if c.Action == HashMod && !model.LabelName(c.TargetLabel).IsValid() {
return errors.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
}
if c.Action == LabelDrop || c.Action == LabelKeep {
if c.SourceLabels != nil ||
c.TargetLabel != DefaultRelabelConfig.TargetLabel ||
c.Modulus != DefaultRelabelConfig.Modulus ||
c.Separator != DefaultRelabelConfig.Separator ||
c.Replacement != DefaultRelabelConfig.Replacement {
return errors.Errorf("%s action requires only 'regex', and no other fields", c.Action)
}
}
return nil
}
// Regexp encapsulates a regexp.Regexp and makes it YAML marshalable.
type Regexp struct {
*regexp.Regexp
original string
}
// NewRegexp creates a new anchored Regexp and returns an error if the
// passed-in regular expression does not compile.
func NewRegexp(s string) (Regexp, error) {
regex, err := regexp.Compile("^(?:" + s + ")$")
return Regexp{
Regexp: regex,
original: s,
}, err
}
// MustNewRegexp works like NewRegexp, but panics if the regular expression does not compile.
func MustNewRegexp(s string) Regexp {
re, err := NewRegexp(s)
if err != nil {
panic(err)
}
return re
}
// UnmarshalYAML implements the yaml.Unmarshaler interface.
func (re *Regexp) UnmarshalYAML(unmarshal func(interface{}) error) error {
var s string
if err := unmarshal(&s); err != nil {
return err
}
r, err := NewRegexp(s)
if err != nil {
return err
}
*re = r
return nil
}
// MarshalYAML implements the yaml.Marshaler interface.
func (re Regexp) MarshalYAML() (interface{}, error) {
if re.original != "" {
return re.original, nil
}
return nil, nil
}
// 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) labels.Labels {
for _, cfg := range cfgs {
labels = relabel(labels, cfg)
if labels == nil {
return nil
}
}
return labels
}
func relabel(lset labels.Labels, cfg *Config) 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 Drop:
if cfg.Regex.MatchString(val) {
return nil
}
case Keep:
if !cfg.Regex.MatchString(val) {
return nil
}
case Replace:
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 HashMod:
mod := sum64(md5.Sum([]byte(val))) % cfg.Modulus
lb.Set(cfg.TargetLabel, fmt.Sprintf("%d", mod))
case LabelMap:
for _, l := range lset {
if cfg.Regex.MatchString(l.Name) {
res := cfg.Regex.ReplaceAllString(l.Name, cfg.Replacement)
lb.Set(res, l.Value)
}
}
case LabelDrop:
for _, l := range lset {
if cfg.Regex.MatchString(l.Name) {
lb.Del(l.Name)
}
}
case LabelKeep:
for _, l := range lset {
if !cfg.Regex.MatchString(l.Name) {
lb.Del(l.Name)
}
}
default:
panic(errors.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
}