Merge pull request #1520 from vrothberg/bz-2216700

layer tree: be more resilient

libimage/layer_tree.go

@@ -2,6 +2,7 @@ package libimage
 
 import (
  "context"
+ "errors"
 
  "github.com/containers/storage"
  ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
@@ -31,6 +32,9 @@ func (t *layerTree) node(layerID string) *layerNode {
 }
 
 // toOCI returns an OCI image for the specified image.
+//
+// WARNING: callers are responsible for handling cases where the target image
+// has been removed and need to check for `storage.ErrImageUnknown`.
 func (t *layerTree) toOCI(ctx context.Context, i *Image) (*ociv1.Image, error) {
  var err error
  oci, exists := t.ociCache[i.ID()]
@@ -155,6 +159,9 @@ func (t *layerTree) children(ctx context.Context, parent *Image, all bool) ([]*I
  parentID := parent.ID()
  parentOCI, err := t.toOCI(ctx, parent)
  if err != nil {
+ if errors.Is(err, storage.ErrImageUnknown) {
+ return nil, nil
+ }
  return nil, err
  }
 
@@ -165,6 +172,9 @@ func (t *layerTree) children(ctx context.Context, parent *Image, all bool) ([]*I
  }
  childOCI, err := t.toOCI(ctx, child)
  if err != nil {
+ if errors.Is(err, storage.ErrImageUnknown) {
+ return false, nil
+ }
  return false, err
  }
  // History check.
@@ -255,6 +265,9 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  childID := child.ID()
  childOCI, err := t.toOCI(ctx, child)
  if err != nil {
+ if errors.Is(err, storage.ErrImageUnknown) {
+ return nil, nil
+ }
  return nil, err
  }
 
@@ -268,6 +281,9 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  }
  emptyOCI, err := t.toOCI(ctx, empty)
  if err != nil {
+ if errors.Is(err, storage.ErrImageUnknown) {
+ return nil, nil
+ }
  return nil, err
  }
  // History check.
@@ -300,6 +316,9 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  }
  parentOCI, err := t.toOCI(ctx, parent)
  if err != nil {
+ if errors.Is(err, storage.ErrImageUnknown) {
+ return nil, nil
+ }
  return nil, err
  }
  // History check.