Fix selection of kustomization resource from multi doc yaml

Signed-off-by: Marcus Weiner <marcus.weiner@gmail.com>

internal/build/build.go

@@ -333,7 +333,7 @@ func (b *Builder) unMarshallKustomization() (*kustomizev1.Kustomization, error)
 	k := &kustomizev1.Kustomization{}
 	decoder := k8syaml.NewYAMLOrJSONDecoder(bytes.NewBuffer(data), len(data))
 	// check for kustomization in yaml with the same name and namespace
-	for !(k.Name == b.name && (k.Namespace == b.namespace || k.Namespace == "")) {
+	for {
 		err = decoder.Decode(k)
 		if err != nil {
 			if err == io.EOF {
@@ -343,6 +343,13 @@ func (b *Builder) unMarshallKustomization() (*kustomizev1.Kustomization, error)
 				return nil, fmt.Errorf("failed to unmarshall kustomization file %s: %w", b.kustomizationFile, err)
 			}
 		}
+
+		if strings.HasPrefix(k.APIVersion, kustomizev1.GroupVersion.Group+"/") &&
+			k.Kind == kustomizev1.KustomizationKind &&
+			k.Name == b.name &&
+			(k.Namespace == b.namespace || k.Namespace == "") {
+			break
+		}
 	}
 	return k, nil
 }

internal/build/build_test.go

@@ -189,6 +189,12 @@ func Test_unMarshallKustomization(t *testing.T) {
 			wantErr:     true,
 			errString:   "failed find kustomization with name",
 		},
+		{
+			name:        "yaml containing other resource with same name as kustomization",
+			localKsFile: "testdata/local-kustomization/invalid-resource.yaml",
+			wantErr:     true,
+			errString:   "failed find kustomization with name",
+		},
 	}
 
 	b := &Builder{
@@ -324,7 +330,10 @@ func Test_ResolveKustomization(t *testing.T) {
 		},
 	}
 
-	b := &Builder{}
+	b := &Builder{
+		name:      "podinfo",
+		namespace: "flux-system",
+	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			b.kustomizationFile = tt.localKsFile

internal/build/testdata/local-kustomization/invalid-resource.yaml

@@ -0,0 +1,4 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: podinfo