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lib/promrelabel: allows regex capture groups in target_label like Pro…
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…metheus does

Updates #569
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@valyala
valyala committed Jun 18, 2020
1 parent ac3700e commit 5820c0f
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Showing 5 changed files with 160 additions and 103 deletions.
4 changes: 4 additions & 0 deletions lib/promrelabel/config.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"fmt"
"io/ioutil"
"regexp"
"strings"

"gopkg.in/yaml.v2"
)
Expand Down Expand Up @@ -124,6 +125,9 @@ func parseRelabelConfig(dst []ParsedRelabelConfig, rc *RelabelConfig) ([]ParsedR
Modulus: modulus,
Replacement: replacement,
Action: action,

hasCaptureGroupInTargetLabel: strings.Contains(targetLabel, "$"),
hasCaptureGroupInReplacement: strings.Contains(replacement, "$"),
})
return dst, nil
}
2 changes: 2 additions & 0 deletions lib/promrelabel/config_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,8 @@ func TestParseRelabelConfigsSuccess(t *testing.T) {
Regex: defaultRegexForRelabelConfig,
Replacement: "$1",
Action: "replace",

hasCaptureGroupInReplacement: true,
},
})
}
Expand Down
76 changes: 44 additions & 32 deletions lib/promrelabel/relabel.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,9 @@ type ParsedRelabelConfig struct {
Modulus uint64
Replacement string
Action string

hasCaptureGroupInTargetLabel bool
hasCaptureGroupInReplacement bool
}

// String returns human-readable representation for prc.
Expand Down Expand Up @@ -103,98 +106,99 @@ func FinalizeLabels(dst, src []prompbmarshal.Label) []prompbmarshal.Label {
return dst
}

// applyRelabelConfig applies relabeling according to cfg.
// applyRelabelConfig applies relabeling according to prc.
//
// See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config
func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, cfg *ParsedRelabelConfig) []prompbmarshal.Label {
func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *ParsedRelabelConfig) []prompbmarshal.Label {
src := labels[labelsOffset:]
switch cfg.Action {
switch prc.Action {
case "replace":
bb := relabelBufPool.Get()
bb.B = concatLabelValues(bb.B[:0], src, cfg.SourceLabels, cfg.Separator)
if len(bb.B) == 0 && cfg.Regex == defaultRegexForRelabelConfig && !strings.Contains(cfg.Replacement, "$") {
bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
if len(bb.B) == 0 && prc.Regex == defaultRegexForRelabelConfig && !prc.hasCaptureGroupInReplacement && !prc.hasCaptureGroupInTargetLabel {
// Fast path for the following rule that just sets label value:
// - target_label: foobar
// replacement: something-here
relabelBufPool.Put(bb)
return setLabelValue(labels, labelsOffset, cfg.TargetLabel, cfg.Replacement)
return setLabelValue(labels, labelsOffset, prc.TargetLabel, prc.Replacement)
}
match := cfg.Regex.FindSubmatchIndex(bb.B)
match := prc.Regex.FindSubmatchIndex(bb.B)
if match == nil {
// Fast path - nothing to replace.
relabelBufPool.Put(bb)
return labels
}
sourceStr := bytesutil.ToUnsafeString(bb.B)
value := relabelBufPool.Get()
value.B = cfg.Regex.ExpandString(value.B[:0], cfg.Replacement, sourceStr, match)
nameStr := prc.TargetLabel
if prc.hasCaptureGroupInTargetLabel {
nameStr = prc.expandCaptureGroups(nameStr, sourceStr, match)
}
valueStr := prc.expandCaptureGroups(prc.Replacement, sourceStr, match)
relabelBufPool.Put(bb)
valueStr := string(value.B)
relabelBufPool.Put(value)
return setLabelValue(labels, labelsOffset, cfg.TargetLabel, valueStr)
return setLabelValue(labels, labelsOffset, nameStr, valueStr)
case "replace_all":
bb := relabelBufPool.Get()
bb.B = concatLabelValues(bb.B[:0], src, cfg.SourceLabels, cfg.Separator)
if !cfg.Regex.Match(bb.B) {
bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
if !prc.Regex.Match(bb.B) {
// Fast path - nothing to replace.
relabelBufPool.Put(bb)
return labels
}
sourceStr := string(bb.B) // Make a copy of bb, since it can be returned from ReplaceAllString
relabelBufPool.Put(bb)
valueStr := cfg.Regex.ReplaceAllString(sourceStr, cfg.Replacement)
return setLabelValue(labels, labelsOffset, cfg.TargetLabel, valueStr)
valueStr := prc.Regex.ReplaceAllString(sourceStr, prc.Replacement)
return setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
case "keep":
bb := relabelBufPool.Get()
bb.B = concatLabelValues(bb.B[:0], src, cfg.SourceLabels, cfg.Separator)
keep := cfg.Regex.Match(bb.B)
bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
keep := prc.Regex.Match(bb.B)
relabelBufPool.Put(bb)
if !keep {
return labels[:labelsOffset]
}
return labels
case "drop":
bb := relabelBufPool.Get()
bb.B = concatLabelValues(bb.B[:0], src, cfg.SourceLabels, cfg.Separator)
drop := cfg.Regex.Match(bb.B)
bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
drop := prc.Regex.Match(bb.B)
relabelBufPool.Put(bb)
if drop {
return labels[:labelsOffset]
}
return labels
case "hashmod":
bb := relabelBufPool.Get()
bb.B = concatLabelValues(bb.B[:0], src, cfg.SourceLabels, cfg.Separator)
h := xxhash.Sum64(bb.B) % cfg.Modulus
bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
h := xxhash.Sum64(bb.B) % prc.Modulus
value := strconv.Itoa(int(h))
relabelBufPool.Put(bb)
return setLabelValue(labels, labelsOffset, cfg.TargetLabel, value)
return setLabelValue(labels, labelsOffset, prc.TargetLabel, value)
case "labelmap":
for i := range src {
label := &src[i]
match := cfg.Regex.FindStringSubmatchIndex(label.Name)
match := prc.Regex.FindStringSubmatchIndex(label.Name)
if match == nil {
continue
}
value := relabelBufPool.Get()
value.B = cfg.Regex.ExpandString(value.B[:0], cfg.Replacement, label.Name, match)
value.B = prc.Regex.ExpandString(value.B[:0], prc.Replacement, label.Name, match)
label.Name = string(value.B)
relabelBufPool.Put(value)
}
return labels
case "labelmap_all":
for i := range src {
label := &src[i]
if !cfg.Regex.MatchString(label.Name) {
if !prc.Regex.MatchString(label.Name) {
continue
}
label.Name = cfg.Regex.ReplaceAllString(label.Name, cfg.Replacement)
label.Name = prc.Regex.ReplaceAllString(label.Name, prc.Replacement)
}
return labels
case "labeldrop":
keepSrc := true
for i := range src {
if cfg.Regex.MatchString(src[i].Name) {
if prc.Regex.MatchString(src[i].Name) {
keepSrc = false
break
}
Expand All @@ -205,15 +209,15 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, cfg *Par
dst := labels[:labelsOffset]
for i := range src {
label := &src[i]
if !cfg.Regex.MatchString(label.Name) {
if !prc.Regex.MatchString(label.Name) {
dst = append(dst, *label)
}
}
return dst
case "labelkeep":
keepSrc := true
for i := range src {
if !cfg.Regex.MatchString(src[i].Name) {
if !prc.Regex.MatchString(src[i].Name) {
keepSrc = false
break
}
Expand All @@ -224,17 +228,25 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, cfg *Par
dst := labels[:labelsOffset]
for i := range src {
label := &src[i]
if cfg.Regex.MatchString(label.Name) {
if prc.Regex.MatchString(label.Name) {
dst = append(dst, *label)
}
}
return dst
default:
logger.Panicf("BUG: unknown `action`: %q", cfg.Action)
logger.Panicf("BUG: unknown `action`: %q", prc.Action)
return labels
}
}

func (prc *ParsedRelabelConfig) expandCaptureGroups(template, source string, match []int) string {
bb := relabelBufPool.Get()
bb.B = prc.Regex.ExpandString(bb.B[:0], template, source, match)
s := string(bb.B)
relabelBufPool.Put(bb)
return s
}

var relabelBufPool bytesutil.ByteBufferPool

func concatLabelValues(dst []byte, labels []prompbmarshal.Label, labelNames []string, separator string) []byte {
Expand Down

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