func relabelingsForSelector()

in pkg/operator/apis/monitoring/v1/common_types.go [38:111]
67 lines of code
13 McCabe index (conditional complexity)

func relabelingsForSelector(selector metav1.LabelSelector, crd interface{}) ([]*relabel.Config, error) {
	// Pick the correct labels based on the CRD type.
	var objectLabelPresent, objectLabel prommodel.LabelName
	switch crd.(type) {
	case *PodMonitoring, *ClusterPodMonitoring:
		objectLabel = "__meta_kubernetes_pod_label_"
		objectLabelPresent = "__meta_kubernetes_pod_labelpresent_"
	case *ClusterNodeMonitoring:
		objectLabel = "__meta_kubernetes_node_label_"
		objectLabelPresent = "__meta_kubernetes_node_labelpresent_"
	default:
		return nil, fmt.Errorf("invalid CRD type %T", crd)
	}
	// Simple equal matchers. Sort by keys first to ensure that generated configs are reproducible.
	// (Go map iteration is non-deterministic.)
	var selectorKeys []string
	for k := range selector.MatchLabels {
		selectorKeys = append(selectorKeys, k)
	}
	sort.Strings(selectorKeys)

	var relabelCfgs []*relabel.Config

	for _, k := range selectorKeys {
		re, err := relabel.NewRegexp(selector.MatchLabels[k])
		if err != nil {
			return nil, err
		}
		relabelCfgs = append(relabelCfgs, &relabel.Config{
			Action:       relabel.Keep,
			SourceLabels: prommodel.LabelNames{objectLabel + sanitizeLabelName(k)},
			Regex:        re,
		})
	}
	// Expression matchers are mapped to relabeling rules with the same behavior.
	for _, exp := range selector.MatchExpressions {
		switch exp.Operator {
		case metav1.LabelSelectorOpIn:
			re, err := relabel.NewRegexp(strings.Join(exp.Values, "|"))
			if err != nil {
				return nil, err
			}
			relabelCfgs = append(relabelCfgs, &relabel.Config{
				Action:       relabel.Keep,
				SourceLabels: prommodel.LabelNames{objectLabel + sanitizeLabelName(exp.Key)},
				Regex:        re,
			})
		case metav1.LabelSelectorOpNotIn:
			re, err := relabel.NewRegexp(strings.Join(exp.Values, "|"))
			if err != nil {
				return nil, err
			}
			relabelCfgs = append(relabelCfgs, &relabel.Config{
				Action:       relabel.Drop,
				SourceLabels: prommodel.LabelNames{objectLabel + sanitizeLabelName(exp.Key)},
				Regex:        re,
			})
		case metav1.LabelSelectorOpExists:
			relabelCfgs = append(relabelCfgs, &relabel.Config{
				Action:       relabel.Keep,
				SourceLabels: prommodel.LabelNames{objectLabelPresent + sanitizeLabelName(exp.Key)},
				Regex:        relabel.MustNewRegexp("true"),
			})
		case metav1.LabelSelectorOpDoesNotExist:
			relabelCfgs = append(relabelCfgs, &relabel.Config{
				Action:       relabel.Drop,
				SourceLabels: prommodel.LabelNames{objectLabelPresent + sanitizeLabelName(exp.Key)},
				Regex:        relabel.MustNewRegexp("true"),
			})
		}
	}

	return relabelCfgs, nil
}