add option to choose prepend/append in merge

api/filters/patchstrategicmerge/patchstrategicmerge.go

@@ -18,7 +18,12 @@ var _ kio.Filter = Filter{}
 func (pf Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
 	var result []*yaml.RNode
 	for i := range nodes {
-		r, err := merge2.Merge(pf.Patch, nodes[i])
+		r, err := merge2.Merge(
+			pf.Patch, nodes[i],
+			yaml.MergeOptions{
+				ListIncreaseDirection: yaml.MergeOptionsListPrepend,
+			},
+		)
 		if err != nil {
 			return nil, err
 		}

api/filters/patchstrategicmerge/patchstrategicmerge_test.go

@@ -67,10 +67,10 @@ spec:
   template:
     spec:
       containers:
+      - name: foo0
       - name: foo1
       - name: foo2
       - name: foo3
-      - name: foo0
 `,
 		},
 		"volumes patch": {
@@ -107,10 +107,10 @@ spec:
   template:
     spec:
       volumes:
+      - name: foo0
       - name: foo1
       - name: foo2
       - name: foo3
-      - name: foo0
 `,
 		},
 		"nested patch": {