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fetcher.go
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fetcher.go
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package target
import (
"context"
"fmt"
"strings"
appsv1 "k8s.io/api/apps/v1"
batchv1 "k8s.io/api/batch/v1"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/meta"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/client-go/scale"
"sigs.k8s.io/controller-runtime/pkg/client"
)
// SelectorFetcher gets a labelSelector used to gather Pods controlled by the given targetRef.
type SelectorFetcher interface {
// Fetch returns a labelSelector used to gather Pods controlled by the given targetRef.
Fetch(targetRef *corev1.ObjectReference) (labels.Selector, error)
}
const (
daemonSet string = "DaemonSet"
deployment string = "Deployment"
replicaSet string = "ReplicaSet"
statefulSet string = "StatefulSet"
replicationController string = "ReplicationController"
job string = "Job"
cronJob string = "CronJob"
)
var wellKnownControllers = sets.NewString(daemonSet, deployment, replicaSet, statefulSet, replicationController, job, cronJob)
// NewSelectorFetcher returns new instance of SelectorFetcher
func NewSelectorFetcher(scheme *runtime.Scheme, restMapper meta.RESTMapper, scaleClient scale.ScalesGetter, kubeClient client.Client) SelectorFetcher {
return &targetSelectorFetcher{
Scheme: scheme,
RestMapper: restMapper,
ScaleClient: scaleClient,
KubeClient: kubeClient,
}
}
type targetSelectorFetcher struct {
Scheme *runtime.Scheme
RestMapper meta.RESTMapper
ScaleClient scale.ScalesGetter
KubeClient client.Client
}
func (f *targetSelectorFetcher) Fetch(target *corev1.ObjectReference) (labels.Selector, error) {
if wellKnownControllers.Has(target.Kind) {
return f.getLabelSelector(target)
}
// not on a list of known controllers, use scale sub-resource
groupVersion, err := schema.ParseGroupVersion(target.APIVersion)
if err != nil {
return nil, err
}
groupKind := schema.GroupKind{
Group: groupVersion.Group,
Kind: target.Kind,
}
selector, err := f.getLabelSelectorFromScale(groupKind, target.Namespace, target.Name)
if err != nil {
return nil, fmt.Errorf("unhandled targetRef %+v, error: %v", *target, err)
}
return selector, nil
}
func (f *targetSelectorFetcher) getLabelSelector(target *corev1.ObjectReference) (labels.Selector, error) {
unstructured := &unstructured.Unstructured{}
unstructured.SetKind(target.Kind)
unstructured.SetAPIVersion(target.APIVersion)
if err := f.KubeClient.Get(context.TODO(), client.ObjectKey{Namespace: target.Namespace, Name: target.Name}, unstructured); err != nil {
return nil, err
}
switch strings.ToLower(target.Kind) {
case strings.ToLower(daemonSet):
var daemonset appsv1.DaemonSet
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &daemonset); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(daemonset.Spec.Selector)
case strings.ToLower(deployment):
var deployment appsv1.Deployment
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &deployment); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(deployment.Spec.Selector)
case strings.ToLower(statefulSet):
var sts appsv1.StatefulSet
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &sts); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(sts.Spec.Selector)
case strings.ToLower(replicaSet):
var rs appsv1.ReplicaSet
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &rs); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(rs.Spec.Selector)
case strings.ToLower(job):
var job batchv1.Job
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &job); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(job.Spec.Selector)
case strings.ToLower(cronJob):
var cjob batchv1.CronJob
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &cjob); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(metav1.SetAsLabelSelector(cjob.Spec.JobTemplate.Spec.Template.Labels))
case strings.ToLower(replicationController):
var rc corev1.ReplicationController
if err := runtime.DefaultUnstructuredConverter.FromUnstructured(unstructured.UnstructuredContent(), &rc); err != nil {
return nil, err
}
return metav1.LabelSelectorAsSelector(metav1.SetAsLabelSelector(rc.Spec.Selector))
}
return nil, fmt.Errorf("unable to fetch label seletor for %+v", *target)
}
func (f *targetSelectorFetcher) getLabelSelectorFromScale(groupKind schema.GroupKind, namespace, name string) (labels.Selector, error) {
mappings, err := f.RestMapper.RESTMappings(groupKind)
if err != nil {
return nil, err
}
var errs []error
for _, mapping := range mappings {
groupResource := mapping.Resource.GroupResource()
scale, err := f.ScaleClient.Scales(namespace).Get(context.TODO(), groupResource, name, metav1.GetOptions{})
if err == nil {
if scale.Status.Selector == "" {
return nil, fmt.Errorf("resource %s/%s has an empty selector for scale sub-resource", namespace, name)
}
selector, err := labels.Parse(scale.Status.Selector)
if err != nil {
return nil, err
}
return selector, nil
}
errs = append(errs, err)
}
return nil, fmt.Errorf("%+v", errs)
}