Merge pull request #5302 from maboehm/fix-multiple-kustomizations

flux diff: Reset target struct before decoding

internal/build/build.go

@@ -464,6 +464,8 @@ func (b *Builder) unMarshallKustomization() (*kustomizev1.Kustomization, error)
 	decoder := k8syaml.NewYAMLOrJSONDecoder(bytes.NewBuffer(data), len(data))
 	// check for kustomization in yaml with the same name and namespace
 	for {
+		// ensure the target struct is emptied before decoding
+		k = &kustomizev1.Kustomization{}
 		err = decoder.Decode(k)
 		if err != nil {
 			if err == io.EOF {

internal/build/build_test.go

@@ -226,6 +226,16 @@ func Test_unMarshallKustomization(t *testing.T) {
 			}
 		})
 	}
+	t.Run("correct parsing of multiple documents", func(t *testing.T) {
+		b.kustomizationFile = "testdata/local-kustomization/multi-doc-reset.yaml"
+		ks, err := b.unMarshallKustomization()
+		if err != nil {
+			t.Errorf("unexpected err '%s'", err)
+		}
+		if len(ks.Spec.Components) > 0 {
+			t.Errorf("previous Kustomization in file leaked into subsequent Kustomizations")
+		}
+	})
 }
 
 func Test_ResolveKustomization(t *testing.T) {

internal/build/testdata/local-kustomization/multi-doc-reset.yaml

@@ -0,0 +1,18 @@
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: first
+  namespace: flux-system
+spec:
+  path: "./k8s/first"
+  components:
+  - foo
+---
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: podinfo
+  namespace: flux-system
+spec:
+  path: "./k8s/second"
+---