Allow patch removal of emptyDir {}

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go

@@ -32,45 +32,57 @@ func (p *plugin) Config(
 		return fmt.Errorf("empty file path and empty patch content")
 	}
 	if len(p.Paths) != 0 {
-		for _, onePath := range p.Paths {
-			// The following oddly attempts to interpret a path string as an
-			// actual patch (instead of as a path to a file containing a patch).
-			// All tests pass if this code is commented out.  This code should
-			// be deleted; the user should use the Patches field which
-			// exists for this purpose (inline patch declaration).
-			res, err := h.ResmapFactory().RF().SliceFromBytes([]byte(onePath))
-			if err == nil {
-				p.loadedPatches = append(p.loadedPatches, res...)
-				continue
-			}
-			res, err = h.ResmapFactory().RF().SliceFromPatches(
-				h.Loader(), []types.PatchStrategicMerge{onePath})
-			if err != nil {
-				return err
-			}
-			p.loadedPatches = append(p.loadedPatches, res...)
-		}
-	}
-	if p.Patches != "" {
-		res, err := h.ResmapFactory().RF().SliceFromBytes([]byte(p.Patches))
+		patches, err := loadFromPaths(h, p.Paths)
 		if err != nil {
 			return err
 		}
-		p.loadedPatches = append(p.loadedPatches, res...)
+		p.loadedPatches = append(p.loadedPatches, patches...)
+	}
+	if p.Patches != "" {
+		patches, err := h.ResmapFactory().RF().SliceFromBytes([]byte(p.Patches))
+		if err != nil {
+			return err
+		}
+		p.loadedPatches = append(p.loadedPatches, patches...)
 	}
-
 	if len(p.loadedPatches) == 0 {
 		return fmt.Errorf(
 			"patch appears to be empty; files=%v, Patch=%s", p.Paths, p.Patches)
 	}
-	// Merge the patches, looking for conflicts.
-	_, err = h.ResmapFactory().ConflatePatches(p.loadedPatches)
-	if err != nil {
-		return err
-	}
+	// TODO(#3723): Delete conflict detection.
+	// Since #1500 closed, the conflict detector in use doesn't do
+	// anything useful.  The resmap returned by this method hasn't
+	// been used for many releases.  Leaving code as a comment to
+	// aid in deletion (fixing #3723).
+	// _, err = h.ResmapFactory().ConflatePatches(p.loadedPatches)
+	// if err != nil {
+	// 	return err
+	// }
 	return nil
 }
 
+func loadFromPaths(
+	h *resmap.PluginHelpers,
+	paths []types.PatchStrategicMerge) (
+	result []*resource.Resource, err error) {
+	var patches []*resource.Resource
+	for _, path := range paths {
+		// For legacy reasons, attempt to treat the path string as
+		// actual patch content.
+		patches, err = h.ResmapFactory().RF().SliceFromBytes([]byte(path))
+		if err != nil {
+			// Failing that, treat it as a file path.
+			patches, err = h.ResmapFactory().RF().SliceFromPatches(
+				h.Loader(), []types.PatchStrategicMerge{path})
+			if err != nil {
+				return
+			}
+		}
+		result = append(result, patches...)
+	}
+	return
+}
+
 func (p *plugin) Transform(m resmap.ResMap) error {
 	for _, patch := range p.loadedPatches {
 		target, err := m.GetById(patch.OrgId())

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer_test.go

@@ -562,6 +562,7 @@ func TestStrategicMergeTransformerNoSchemaMultiPatchesNoConflict(t *testing.T) {
 	th := kusttest_test.MakeEnhancedHarness(t).
 		PrepBuiltin("PatchStrategicMergeTransformer")
 	defer th.Reset()
+	// This patch wants to delete "B".
 	th.WriteF("patch1.yaml", `
 apiVersion: example.com/v1
 kind: Foo
@@ -603,10 +604,6 @@ spec:
 `)
 	assert.NoError(t, err)
 	th.AssertActualEqualsExpectedNoIdAnnotations(
-		// In kyaml/yaml.merge2, the empty "B: " is dropped
-		// when patch1 and patch2 are merged, so the patch
-		// applied is effectively only patch2.yaml.
-		// So it cannot delete the "B: Y"
 		resMap, `
 apiVersion: example.com/v1
 kind: Foo
@@ -615,7 +612,6 @@ metadata:
 spec:
   bar:
     A: X
-    B: "Y"
     C: Z
     D: W
   baz:
@@ -639,8 +635,7 @@ spec:
 `)
 	assert.NoError(t, err)
 	th.AssertActualEqualsExpectedNoIdAnnotations(
-		// This time only patch2 was applied.  Same answer on the kyaml
-		// path, but different answer on apimachinery path (B becomes "true"?)
+		// This time only patch2 is applied.
 		resMap, `
 apiVersion: example.com/v1
 kind: Foo