k8s: Support circular owner references (#6238)

Signed-off-by: Matthew Terwilliger <[email protected]>

internal/k8s/owner_fetcher.go

@@ -6,6 +6,7 @@ import (
  "strings"
  "sync"
 
+ "golang.org/x/exp/slices"
  v1 "k8s.io/api/core/v1"
  "k8s.io/apimachinery/pkg/api/errors"
  metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -147,6 +148,10 @@ func (v OwnerFetcher) getOrCreatePromise(id types.UID) (*objectTreePromise, bool
 }
 
 func (v OwnerFetcher) OwnerTreeOfRef(ctx context.Context, ref v1.ObjectReference) (result ObjectRefTree, err error) {
+ return v.ownerTreeOfRefHelper(ctx, ref, nil)
+}
+
+func (v OwnerFetcher) ownerTreeOfRefHelper(ctx context.Context, ref v1.ObjectReference, path []types.UID) (result ObjectRefTree, err error) {
  uid := ref.UID
  if uid == "" {
  return ObjectRefTree{}, fmt.Errorf("Can only get owners of deployed entities")
@@ -172,7 +177,7 @@ func (v OwnerFetcher) OwnerTreeOfRef(ctx context.Context, ref v1.ObjectReference
  }
  return ObjectRefTree{}, err
  }
- return v.ownerTreeOfHelper(ctx, ref, meta)
+ return v.ownerTreeOfHelper(ctx, ref, meta, path)
 }
 
 func (v OwnerFetcher) getMetaByReference(ctx context.Context, ref v1.ObjectReference) (metav1.Object, error) {
@@ -211,15 +216,20 @@ func (v OwnerFetcher) OwnerTreeOf(ctx context.Context, entity K8sEntity) (result
  }()
 
  ref := entity.ToObjectReference()
- return v.ownerTreeOfHelper(ctx, ref, meta)
+ return v.ownerTreeOfHelper(ctx, ref, meta, nil)
 }
 
-func (v OwnerFetcher) ownerTreeOfHelper(ctx context.Context, ref v1.ObjectReference, meta metav1.Object) (ObjectRefTree, error) {
+func (v OwnerFetcher) ownerTreeOfHelper(ctx context.Context, ref v1.ObjectReference, meta metav1.Object, path []types.UID) (ObjectRefTree, error) {
  tree := ObjectRefTree{Ref: ref, CreationTimestamp: meta.GetCreationTimestamp()}
  owners := meta.GetOwnerReferences()
  for _, owner := range owners {
+ // TODO: Owner references can also exist at cluster scope, for which this incorrectly propagates the parent ref's Namespace.
  ownerRef := OwnerRefToObjectRef(owner, meta.GetNamespace())
- ownerTree, err := v.OwnerTreeOfRef(ctx, ownerRef)
+ if slices.Contains(path, owner.UID) {
+ // break circular dependencies
+ continue
+ }
+ ownerTree, err := v.ownerTreeOfRefHelper(ctx, ownerRef, append(path, ref.UID))
  if err != nil {
  return ObjectRefTree{}, err
  }

internal/k8s/owner_fetcher_test.go

@@ -79,6 +79,21 @@ func TestOwnerFetcherParallelism(t *testing.T) {
  assert.Equal(t, 1, kCli.getByReferenceCallCount)
 }
 
+func TestCircular(t *testing.T) {
+ kCli := NewFakeK8sClient(t)
+ kCli.listReturnsEmpty = true
+ ov := NewOwnerFetcher(context.Background(), kCli)
+
+ pod1, pod2, pod3 := fakeCircularReference()
+ kCli.Inject(NewK8sEntity(pod2), NewK8sEntity(pod3))
+
+ tree, err := ov.OwnerTreeOf(context.Background(), NewK8sEntity(pod1))
+ assert.NoError(t, err)
+ assert.Equal(t, `Pod:pod-a
+ Pod:pod-b
+ Pod:pod-c`, tree.String())
+}
+
 func fakeOneParentChain() (*v1.Pod, *appsv1.ReplicaSet) {
  pod := &v1.Pod{
  ObjectMeta: metav1.ObjectMeta{
@@ -145,3 +160,53 @@ func fakeTwoParentChain() (*v1.Pod, *appsv1.ReplicaSet, *appsv1.Deployment) {
  }
  return pod, rs, dep
 }
+
+func fakeCircularReference() (*v1.Pod, *v1.Pod, *v1.Pod) {
+ pod1 := &v1.Pod{
+ ObjectMeta: metav1.ObjectMeta{
+ Name: "pod-a",
+ UID: "pod-a-uid",
+ Namespace: "default",
+ OwnerReferences: []metav1.OwnerReference{
+ {
+ APIVersion: "v1",
+ Kind: "Pod",
+ Name: "pod-b",
+ UID: "pod-b-uid",
+ },
+ },
+ },
+ }
+ pod2 := &v1.Pod{
+ ObjectMeta: metav1.ObjectMeta{
+ Name: "pod-b",
+ UID: "pod-b-uid",
+ Namespace: "default",
+ OwnerReferences: []metav1.OwnerReference{
+ {
+ APIVersion: "v1",
+ Kind: "Pod",
+ Name: "pod-c",
+ UID: "pod-c-uid",
+ },
+ },
+ },
+ }
+ pod3 := &v1.Pod{
+ ObjectMeta: metav1.ObjectMeta{
+ Name: "pod-c",
+ UID: "pod-c-uid",
+ Namespace: "default",
+ OwnerReferences: []metav1.OwnerReference{
+ {
+ APIVersion: "v1",
+ Kind: "Pod",
+ Name: "pod-a",
+ UID: "pod-a-uid",
+ },
+ },
+ },
+ }
+
+ return pod1, pod2, pod3
+}