94 lines
2.3 KiB
Go
94 lines
2.3 KiB
Go
package retrieval
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import (
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"crypto/md5"
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"fmt"
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"strings"
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clientmodel "github.com/prometheus/client_golang/model"
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"github.com/prometheus/prometheus/config"
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)
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// Relabel returns a relabeled copy of the given label set. The relabel configurations
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// are applied in order of input.
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// If a label set is dropped, nil is returned.
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func Relabel(labels clientmodel.LabelSet, cfgs ...*config.RelabelConfig) (clientmodel.LabelSet, error) {
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out := clientmodel.LabelSet{}
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for ln, lv := range labels {
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out[ln] = lv
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}
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var err error
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for _, cfg := range cfgs {
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if out, err = relabel(out, cfg); err != nil {
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return nil, err
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}
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if out == nil {
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return nil, nil
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}
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}
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return out, nil
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}
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func relabel(labels clientmodel.LabelSet, cfg *config.RelabelConfig) (clientmodel.LabelSet, error) {
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values := make([]string, 0, len(cfg.SourceLabels))
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for _, ln := range cfg.SourceLabels {
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values = append(values, string(labels[ln]))
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}
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val := strings.Join(values, cfg.Separator)
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switch cfg.Action {
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case config.RelabelDrop:
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if cfg.Regex.MatchString(val) {
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return nil, nil
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}
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case config.RelabelKeep:
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if !cfg.Regex.MatchString(val) {
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return nil, nil
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}
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case config.RelabelReplace:
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indexes := cfg.Regex.FindStringSubmatchIndex(val)
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// If there is no match no replacement must take place.
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if indexes == nil {
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break
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}
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res := cfg.Regex.ExpandString([]byte{}, cfg.Replacement, val, indexes)
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if len(res) == 0 {
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delete(labels, cfg.TargetLabel)
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} else {
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labels[cfg.TargetLabel] = clientmodel.LabelValue(res)
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}
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case config.RelabelHashMod:
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mod := sum64(md5.Sum([]byte(val))) % cfg.Modulus
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labels[cfg.TargetLabel] = clientmodel.LabelValue(fmt.Sprintf("%d", mod))
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case config.RelabelLabelMap:
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out := make(clientmodel.LabelSet, len(labels))
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// Take a copy to avoid infinite loops.
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for ln, lv := range labels {
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out[ln] = lv
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}
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for ln, lv := range labels {
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if cfg.Regex.MatchString(string(ln)) {
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res := cfg.Regex.ReplaceAllString(string(ln), cfg.Replacement)
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out[clientmodel.LabelName(res)] = lv
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}
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}
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labels = out
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default:
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panic(fmt.Errorf("retrieval.relabel: unknown relabel action type %q", cfg.Action))
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}
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return labels, nil
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}
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// sum64 sums the md5 hash to an uint64.
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func sum64(hash [md5.Size]byte) uint64 {
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var s uint64
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for i, b := range hash {
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shift := uint64((md5.Size - i - 1) * 8)
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s |= uint64(b) << shift
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}
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return s
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}
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