mirror of
https://github.com/kubernetes-sigs/prometheus-adapter.git
synced 2026-04-05 17:27:51 +00:00
100 lines
3 KiB
Go
100 lines
3 KiB
Go
/*
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Copyright 2019 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package naming
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import (
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"bytes"
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"fmt"
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"regexp"
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"text/template"
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"k8s.io/apimachinery/pkg/runtime/schema"
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pmodel "github.com/prometheus/common/model"
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)
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// labelGroupResExtractor extracts schema.GroupResources from series labels.
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type labelGroupResExtractor struct {
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regex *regexp.Regexp
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resourceInd int
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groupInd *int
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}
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// newLabelGroupResExtractor creates a new labelGroupResExtractor for labels whose form
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// matches the given template. It does so by creating a regular expression from the template,
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// so anything in the template which limits resource or group name length will cause issues.
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func newLabelGroupResExtractor(labelTemplate *template.Template) (*labelGroupResExtractor, error) {
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labelRegexBuff := new(bytes.Buffer)
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if err := labelTemplate.Execute(labelRegexBuff, schema.GroupResource{
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Group: "(?P<group>.+?)",
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Resource: "(?P<resource>.+?)"},
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); err != nil {
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return nil, fmt.Errorf("unable to convert label template to matcher: %v", err)
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}
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if labelRegexBuff.Len() == 0 {
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return nil, fmt.Errorf("unable to convert label template to matcher: empty template")
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}
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labelRegexRaw := "^" + labelRegexBuff.String() + "$"
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labelRegex, err := regexp.Compile(labelRegexRaw)
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if err != nil {
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return nil, fmt.Errorf("unable to convert label template to matcher: %v", err)
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}
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var groupInd *int
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var resInd *int
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for i, name := range labelRegex.SubexpNames() {
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switch name {
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case "group":
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ind := i // copy to avoid iteration variable reference
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groupInd = &ind
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case "resource":
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ind := i // copy to avoid iteration variable reference
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resInd = &ind
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}
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}
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if resInd == nil {
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return nil, fmt.Errorf("must include at least `{{.Resource}}` in the label template")
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}
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return &labelGroupResExtractor{
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regex: labelRegex,
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resourceInd: *resInd,
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groupInd: groupInd,
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}, nil
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}
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// GroupResourceForLabel extracts a schema.GroupResource from the given label, if possible.
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// The second return value indicates whether or not a potential group-resource was found in this label.
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func (e *labelGroupResExtractor) GroupResourceForLabel(lbl pmodel.LabelName) (schema.GroupResource, bool) {
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matchGroups := e.regex.FindStringSubmatch(string(lbl))
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if matchGroups != nil {
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group := ""
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if e.groupInd != nil {
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group = matchGroups[*e.groupInd]
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}
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return schema.GroupResource{
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Group: group,
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Resource: matchGroups[e.resourceInd],
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}, true
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}
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return schema.GroupResource{}, false
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}
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