apiextensions: implement x-kubernetes-embedded-resource algorithm

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/algorithm.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package objectmeta
+
+import (
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+// Coerce checks types of embedded ObjectMeta and TypeMeta and prunes unknown fields inside the former.
+// It does coerce ObjectMeta and TypeMeta at the root if includeRoot is true.
+// If dropInvalidFields is true, fields of wrong type will be dropped.
+func Coerce(pth *field.Path, obj interface{}, s *structuralschema.Structural, includeRoot, dropInvalidFields bool) *field.Error {
+	if includeRoot {
+		if s == nil {
+			s = &structuralschema.Structural{}
+		}
+		clone := *s
+		clone.XEmbeddedResource = true
+		s = &clone
+	}
+	c := coercer{dropInvalidFields: dropInvalidFields}
+	return c.coerce(pth, obj, s)
+}
+
+type coercer struct {
+	dropInvalidFields bool
+}
+
+func (c *coercer) coerce(pth *field.Path, x interface{}, s *structuralschema.Structural) *field.Error {
+	if s == nil {
+		return nil
+	}
+	switch x := x.(type) {
+	case map[string]interface{}:
+		for k, v := range x {
+			if s.XEmbeddedResource {
+				switch k {
+				case "apiVersion", "kind":
+					if _, ok := v.(string); !ok && c.dropInvalidFields {
+						delete(x, k)
+					} else if !ok {
+						return field.Invalid(pth, v, "must be a string")
+					}
+				case "metadata":
+					meta, found, err := GetObjectMeta(x, c.dropInvalidFields)
+					if err != nil {
+						if !c.dropInvalidFields {
+							return field.Invalid(pth.Child("metadata"), v, err.Error())
+						}
+						// pass through on error if dropInvalidFields is true
+					} else if found {
+						if err := SetObjectMeta(x, meta); err != nil {
+							return field.Invalid(pth.Child("metadata"), v, err.Error())
+						}
+						if meta.CreationTimestamp.IsZero() {
+							unstructured.RemoveNestedField(x, "metadata", "creationTimestamp")
+						}
+					}
+				}
+			}
+			prop, ok := s.Properties[k]
+			if ok {
+				if err := c.coerce(pth.Child(k), v, &prop); err != nil {
+					return err
+				}
+			} else if s.AdditionalProperties != nil {
+				if err := c.coerce(pth.Key(k), v, s.AdditionalProperties.Structural); err != nil {
+					return err
+				}
+			}
+		}
+	case []interface{}:
+		for i, v := range x {
+			if err := c.coerce(pth.Index(i), v, s.Items); err != nil {
+				return err
+			}
+		}
+	default:
+		// scalars, do nothing
+	}
+
+	return nil
+}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/algorithm_test.go

@@ -0,0 +1,515 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package objectmeta
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	"k8s.io/apimachinery/pkg/util/diff"
+	"k8s.io/apimachinery/pkg/util/json"
+)
+
+func TestCoerce(t *testing.T) {
+	tests := []struct {
+		name              string
+		json              string
+		includeRoot       bool
+		dropInvalidFields bool
+		schema            *structuralschema.Structural
+		expected          string
+		expectedError     bool
+	}{
+		{name: "empty", json: "null", schema: nil, expected: "null"},
+		{name: "scalar", json: "4", schema: &structuralschema.Structural{}, expected: "4"},
+		{name: "scalar array", json: "[1,2]", schema: &structuralschema.Structural{
+			Items: &structuralschema.Structural{},
+		}, expected: "[1,2]"},
+		{name: "x-kubernetes-embedded-resource", json: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance",
+    "unspecified": "bar"
+  },
+  "unspecified":"bar",
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "preserving": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "nested": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar",
+      "embedded": {
+        "apiVersion": "foo/v1",
+        "kind": "Foo",
+        "unspecified": "bar",
+        "metadata": {
+          "name": "instance",
+          "unspecified": "bar"
+        },
+        "spec": {
+          "unspecified": "bar"
+        }
+      }
+    }
+  }
+}
+`, schema: &structuralschema.Structural{
+			Generic: structuralschema.Generic{Type: "object"},
+			Properties: map[string]structuralschema.Structural{
+				"pruned": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+					Properties: map[string]structuralschema.Structural{
+						"spec": {
+							Generic: structuralschema.Generic{Type: "object"},
+						},
+					},
+				},
+				"preserving": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource:      true,
+						XPreserveUnknownFields: true,
+					},
+				},
+				"nested": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+					Properties: map[string]structuralschema.Structural{
+						"spec": {
+							Generic: structuralschema.Generic{Type: "object"},
+							Properties: map[string]structuralschema.Structural{
+								"embedded": {
+									Generic: structuralschema.Generic{Type: "object"},
+									Extensions: structuralschema.Extensions{
+										XEmbeddedResource: true,
+									},
+									Properties: map[string]structuralschema.Structural{
+										"spec": {
+											Generic: structuralschema.Generic{Type: "object"},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		}, expected: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance",
+    "unspecified": "bar"
+  },
+  "unspecified":"bar",
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "preserving": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "nested": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar",
+      "embedded": {
+        "apiVersion": "foo/v1",
+        "kind": "Foo",
+        "unspecified": "bar",
+        "metadata": {
+          "name": "instance"
+        },
+        "spec": {
+          "unspecified": "bar"
+        }
+      }
+    }
+  }
+}
+`},
+		{name: "x-kubernetes-embedded-resource, with includeRoot=true", json: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance",
+    "unspecified": "bar"
+  },
+  "unspecified":"bar",
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "preserving": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "nested": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance",
+      "unspecified": "bar"
+    },
+    "spec": {
+      "unspecified": "bar",
+      "embedded": {
+        "apiVersion": "foo/v1",
+        "kind": "Foo",
+        "unspecified": "bar",
+        "metadata": {
+          "name": "instance",
+          "unspecified": "bar"
+        },
+        "spec": {
+          "unspecified": "bar"
+        }
+      }
+    }
+  }
+}
+`, includeRoot: true, schema: &structuralschema.Structural{
+			Generic: structuralschema.Generic{Type: "object"},
+			Properties: map[string]structuralschema.Structural{
+				"pruned": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+					Properties: map[string]structuralschema.Structural{
+						"spec": {
+							Generic: structuralschema.Generic{Type: "object"},
+						},
+					},
+				},
+				"preserving": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource:      true,
+						XPreserveUnknownFields: true,
+					},
+				},
+				"nested": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+					Properties: map[string]structuralschema.Structural{
+						"spec": {
+							Generic: structuralschema.Generic{Type: "object"},
+							Properties: map[string]structuralschema.Structural{
+								"embedded": {
+									Generic: structuralschema.Generic{Type: "object"},
+									Extensions: structuralschema.Extensions{
+										XEmbeddedResource: true,
+									},
+									Properties: map[string]structuralschema.Structural{
+										"spec": {
+											Generic: structuralschema.Generic{Type: "object"},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		}, expected: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "unspecified":"bar",
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "preserving": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar"
+    }
+  },
+  "nested": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "unspecified": "bar",
+    "metadata": {
+      "name": "instance"
+    },
+    "spec": {
+      "unspecified": "bar",
+      "embedded": {
+        "apiVersion": "foo/v1",
+        "kind": "Foo",
+        "unspecified": "bar",
+        "metadata": {
+          "name": "instance"
+        },
+        "spec": {
+          "unspecified": "bar"
+        }
+      }
+    }
+  }
+}
+`},
+		{name: "without name", json: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "metadata": {
+      "namespace": "kube-system"
+    }
+  }
+}
+`, schema: &structuralschema.Structural{
+			Generic: structuralschema.Generic{Type: "object"},
+			Properties: map[string]structuralschema.Structural{
+				"pruned": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+				},
+			},
+		}, expected: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "apiVersion": "foo/v1",
+    "kind": "Foo",
+    "metadata": {
+      "namespace": "kube-system"
+    }
+  }
+}
+`},
+		{name: "x-kubernetes-embedded-resource, with dropInvalidFields=true", json: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "apiVersion": 42,
+    "kind": 42,
+    "metadata": {
+      "name": "instance",
+	  "namespace": ["abc"],
+      "labels": {
+        "foo": 42
+      }
+    }
+  }
+}
+`, dropInvalidFields: true, schema: &structuralschema.Structural{
+			Generic: structuralschema.Generic{Type: "object"},
+			Properties: map[string]structuralschema.Structural{
+				"pruned": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+					Properties: map[string]structuralschema.Structural{
+						"spec": {
+							Generic: structuralschema.Generic{Type: "object"},
+						},
+					},
+				},
+			},
+		}, expected: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "metadata": {
+      "name": "instance"
+    }
+  }
+}
+`},
+		{name: "invalid metadata type, with dropInvalidFields=true", json: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "apiVersion": 42,
+    "kind": 42,
+    "metadata": [42]
+  }
+}
+`, dropInvalidFields: true, schema: &structuralschema.Structural{
+			Generic: structuralschema.Generic{Type: "object"},
+			Properties: map[string]structuralschema.Structural{
+				"pruned": {
+					Generic: structuralschema.Generic{Type: "object"},
+					Extensions: structuralschema.Extensions{
+						XEmbeddedResource: true,
+					},
+				},
+			},
+		}, expected: `
+{
+  "apiVersion": "foo/v1",
+  "kind": "Foo",
+  "metadata": {
+    "name": "instance"
+  },
+  "pruned": {
+    "metadata": [42]
+  }
+}
+`},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var in interface{}
+			if err := json.Unmarshal([]byte(tt.json), &in); err != nil {
+				t.Fatal(err)
+			}
+
+			var expected interface{}
+			if err := json.Unmarshal([]byte(tt.expected), &expected); err != nil {
+				t.Fatal(err)
+			}
+
+			err := Coerce(nil, in, tt.schema, tt.includeRoot, tt.dropInvalidFields)
+			if tt.expectedError && err == nil {
+				t.Error("expected error, but did not get any")
+			} else if !tt.expectedError && err != nil {
+				t.Errorf("expected no error, but got: %v", err)
+			} else if !reflect.DeepEqual(in, expected) {
+				var buf bytes.Buffer
+				enc := json.NewEncoder(&buf)
+				enc.SetIndent("", "  ")
+				err := enc.Encode(in)
+				if err != nil {
+					t.Fatalf("unexpected result mashalling error: %v", err)
+				}
+				t.Errorf("expected: %s\ngot: %s\ndiff: %s", tt.expected, buf.String(), diff.ObjectDiff(expected, in))
+			}
+		})
+	}
+}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce.go

@@ -27,13 +27,16 @@ import (
 
 var encodingjson = json.CaseSensitiveJsonIterator()
 
-func GetObjectMeta(u *unstructured.Unstructured, dropMalformedFields bool) (*metav1.ObjectMeta, bool, error) {
+// GetObjectMeta does conversion of JSON to ObjectMeta. It first tries json.Unmarshal into a metav1.ObjectMeta
-	metadata, found := u.UnstructuredContent()["metadata"]
+// type. If that does not work and dropMalformedFields is true, it does field-by-field best-effort conversion
+// throwing away fields which lead to errors.
+func GetObjectMeta(obj map[string]interface{}, dropMalformedFields bool) (*metav1.ObjectMeta, bool, error) {
+	metadata, found := obj["metadata"]
 	if !found {
 		return nil, false, nil
 	}
 
-	// round-trip through JSON first, hoping that unmarshaling just works
+	// round-trip through JSON first, hoping that unmarshalling just works
 	objectMeta := &metav1.ObjectMeta{}
 	metadataBytes, err := encodingjson.Marshal(metadata)
 	if err != nil {
@@ -72,9 +75,10 @@ func GetObjectMeta(u *unstructured.Unstructured, dropMalformedFields bool) (*met
 	return accumulatedObjectMeta, true, nil
 }
 
-func SetObjectMeta(u *unstructured.Unstructured, objectMeta *metav1.ObjectMeta) error {
+// SetObjectMeta writes back ObjectMeta into a JSON data structure.
+func SetObjectMeta(obj map[string]interface{}, objectMeta *metav1.ObjectMeta) error {
 	if objectMeta == nil {
-		unstructured.RemoveNestedField(u.UnstructuredContent(), "metadata")
+		unstructured.RemoveNestedField(obj, "metadata")
 		return nil
 	}
 
@@ -83,6 +87,6 @@ func SetObjectMeta(u *unstructured.Unstructured, objectMeta *metav1.ObjectMeta)
 		return err
 	}
 
-	u.UnstructuredContent()["metadata"] = metadata
+	obj["metadata"] = metadata
 	return nil
 }

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce_test.go

@@ -46,10 +46,10 @@ func TestRoundtripObjectMeta(t *testing.T) {
 		u := &unstructured.Unstructured{Object: map[string]interface{}{}}
 		original := &metav1.ObjectMeta{}
 		fuzzer.Fuzz(original)
-		if err := SetObjectMeta(u, original); err != nil {
+		if err := SetObjectMeta(u.Object, original); err != nil {
 			t.Fatalf("unexpected error setting ObjectMeta: %v", err)
 		}
-		o, _, err := GetObjectMeta(u, false)
+		o, _, err := GetObjectMeta(u.Object, false)
 		if err != nil {
 			t.Fatalf("unexpected error getting the Objectmeta: %v", err)
 		}
@@ -96,7 +96,7 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 		for _, pth := range jsonPaths(nil, goodMetaMap) {
 			for _, v := range spuriousValues() {
 				// skip values of same type, because they can only cause decoding errors further insides
-				orig, err := JsonPathValue(goodMetaMap, pth, 0)
+				orig, err := JSONPathValue(goodMetaMap, pth, 0)
 				if err != nil {
 					t.Fatalf("unexpected to not find something at %v: %v", pth, err)
 				}
@@ -109,7 +109,7 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 				if err != nil {
 					t.Fatal(err)
 				}
-				if err := SetJsonPath(spuriousMetaMap, pth, 0, v); err != nil {
+				if err := SetJSONPath(spuriousMetaMap, pth, 0, v); err != nil {
 					t.Fatal(err)
 				}
 
@@ -130,7 +130,7 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 					switch {
 					default:
 						// delete complete top-level field by default
-						DeleteJsonPath(truncatedMetaMap, pth[:1], 0)
+						DeleteJSONPath(truncatedMetaMap, pth[:1], 0)
 					}
 
 					truncatedJSON, err := encodingjson.Marshal(truncatedMetaMap)
@@ -145,7 +145,7 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 
 				// make sure dropInvalidTypedFields+getObjectMeta matches what we expect
 				u := &unstructured.Unstructured{Object: map[string]interface{}{"metadata": spuriousMetaMap}}
-				actualObjectMeta, _, err := GetObjectMeta(u, true)
+				actualObjectMeta, _, err := GetObjectMeta(u.Object, true)
 				if err != nil {
 					t.Errorf("got unexpected error after dropping invalid typed fields on %v=%#v: %v", pth, v, err)
 					continue
@@ -174,7 +174,7 @@ func TestGetObjectMetaNils(t *testing.T) {
 		},
 	}
 
-	o, _, err := GetObjectMeta(u, true)
+	o, _, err := GetObjectMeta(u.Object, true)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -223,7 +223,7 @@ func TestGetObjectMeta(t *testing.T) {
 			},
 		}}
 
-		meta, _, err := GetObjectMeta(u, true)
+		meta, _, err := GetObjectMeta(u.Object, true)
 		if err != nil {
 			t.Fatal(err)
 		}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/jsonpath_test.go

@@ -28,10 +28,10 @@ type (
 		index *int
 		field string
 	}
-	JsonPath []jsonPathNode
+	JSONPath []jsonPathNode
 )
 
-func (p JsonPath) String() string {
+func (p JSONPath) String() string {
 	var buf bytes.Buffer
 	for _, n := range p {
 		if n.index == nil {
@@ -43,8 +43,8 @@ func (p JsonPath) String() string {
 	return buf.String()
 }
 
-func jsonPaths(base JsonPath, j map[string]interface{}) []JsonPath {
+func jsonPaths(base JSONPath, j map[string]interface{}) []JSONPath {
-	res := make([]JsonPath, 0, len(j))
+	res := make([]JSONPath, 0, len(j))
 	for k, old := range j {
 		kPth := append(append([]jsonPathNode(nil), base...), jsonPathNode{field: k})
 		res = append(res, kPth)
@@ -59,8 +59,8 @@ func jsonPaths(base JsonPath, j map[string]interface{}) []JsonPath {
 	return res
 }
 
-func jsonIterSlice(base JsonPath, j []interface{}) []JsonPath {
+func jsonIterSlice(base JSONPath, j []interface{}) []JSONPath {
-	res := make([]JsonPath, 0, len(j))
+	res := make([]JSONPath, 0, len(j))
 	for i, old := range j {
 		index := i
 		iPth := append(append([]jsonPathNode(nil), base...), jsonPathNode{index: &index})
@@ -76,7 +76,7 @@ func jsonIterSlice(base JsonPath, j []interface{}) []JsonPath {
 	return res
 }
 
-func JsonPathValue(j map[string]interface{}, pth JsonPath, base int) (interface{}, error) {
+func JSONPathValue(j map[string]interface{}, pth JSONPath, base int) (interface{}, error) {
 	if len(pth) == base {
 		return nil, fmt.Errorf("empty json path is invalid for object")
 	}
@@ -92,7 +92,7 @@ func JsonPathValue(j map[string]interface{}, pth JsonPath, base int) (interface{
 	}
 	switch field := field.(type) {
 	case map[string]interface{}:
-		return JsonPathValue(field, pth, base+1)
+		return JSONPathValue(field, pth, base+1)
 	case []interface{}:
 		return jsonPathValueSlice(field, pth, base+1)
 	default:
@@ -100,7 +100,7 @@ func JsonPathValue(j map[string]interface{}, pth JsonPath, base int) (interface{
 	}
 }
 
-func jsonPathValueSlice(j []interface{}, pth JsonPath, base int) (interface{}, error) {
+func jsonPathValueSlice(j []interface{}, pth JSONPath, base int) (interface{}, error) {
 	if len(pth) == base {
 		return nil, fmt.Errorf("empty json path %q is invalid for object", pth)
 	}
@@ -115,7 +115,7 @@ func jsonPathValueSlice(j []interface{}, pth JsonPath, base int) (interface{}, e
 	}
 	switch item := j[*pth[base].index].(type) {
 	case map[string]interface{}:
-		return JsonPathValue(item, pth, base+1)
+		return JSONPathValue(item, pth, base+1)
 	case []interface{}:
 		return jsonPathValueSlice(item, pth, base+1)
 	default:
@@ -123,7 +123,7 @@ func jsonPathValueSlice(j []interface{}, pth JsonPath, base int) (interface{}, e
 	}
 }
 
-func SetJsonPath(j map[string]interface{}, pth JsonPath, base int, value interface{}) error {
+func SetJSONPath(j map[string]interface{}, pth JSONPath, base int, value interface{}) error {
 	if len(pth) == base {
 		return fmt.Errorf("empty json path is invalid for object")
 	}
@@ -140,15 +140,15 @@ func SetJsonPath(j map[string]interface{}, pth JsonPath, base int, value interfa
 	}
 	switch field := field.(type) {
 	case map[string]interface{}:
-		return SetJsonPath(field, pth, base+1, value)
+		return SetJSONPath(field, pth, base+1, value)
 	case []interface{}:
-		return setJsonPathSlice(field, pth, base+1, value)
+		return setJSONPathSlice(field, pth, base+1, value)
 	default:
 		return fmt.Errorf("invalid non-terminal json path %q for field", pth[:base+1])
 	}
 }
 
-func setJsonPathSlice(j []interface{}, pth JsonPath, base int, value interface{}) error {
+func setJSONPathSlice(j []interface{}, pth JSONPath, base int, value interface{}) error {
 	if len(pth) == base {
 		return fmt.Errorf("empty json path %q is invalid for object", pth)
 	}
@@ -164,15 +164,15 @@ func setJsonPathSlice(j []interface{}, pth JsonPath, base int, value interface{}
 	}
 	switch item := j[*pth[base].index].(type) {
 	case map[string]interface{}:
-		return SetJsonPath(item, pth, base+1, value)
+		return SetJSONPath(item, pth, base+1, value)
 	case []interface{}:
-		return setJsonPathSlice(item, pth, base+1, value)
+		return setJSONPathSlice(item, pth, base+1, value)
 	default:
 		return fmt.Errorf("invalid non-terminal json path %q for index", pth[:base+1])
 	}
 }
 
-func DeleteJsonPath(j map[string]interface{}, pth JsonPath, base int) error {
+func DeleteJSONPath(j map[string]interface{}, pth JSONPath, base int) error {
 	if len(pth) == base {
 		return fmt.Errorf("empty json path is invalid for object")
 	}
@@ -189,7 +189,7 @@ func DeleteJsonPath(j map[string]interface{}, pth JsonPath, base int) error {
 	}
 	switch field := field.(type) {
 	case map[string]interface{}:
-		return DeleteJsonPath(field, pth, base+1)
+		return DeleteJSONPath(field, pth, base+1)
 	case []interface{}:
 		if len(pth) == base+2 {
 			if pth[base+1].index == nil {
@@ -198,13 +198,13 @@ func DeleteJsonPath(j map[string]interface{}, pth JsonPath, base int) error {
 			j[pth[base].field] = append(field[:*pth[base+1].index], field[*pth[base+1].index+1:]...)
 			return nil
 		}
-		return deleteJsonPathSlice(field, pth, base+1)
+		return deleteJSONPathSlice(field, pth, base+1)
 	default:
 		return fmt.Errorf("invalid non-terminal json path %q for field", pth[:base+1])
 	}
 }
 
-func deleteJsonPathSlice(j []interface{}, pth JsonPath, base int) error {
+func deleteJSONPathSlice(j []interface{}, pth JSONPath, base int) error {
 	if len(pth) == base {
 		return fmt.Errorf("empty json path %q is invalid for object", pth)
 	}
@@ -219,7 +219,7 @@ func deleteJsonPathSlice(j []interface{}, pth JsonPath, base int) error {
 	}
 	switch item := j[*pth[base].index].(type) {
 	case map[string]interface{}:
-		return DeleteJsonPath(item, pth, base+1)
+		return DeleteJSONPath(item, pth, base+1)
 	case []interface{}:
 		if len(pth) == base+2 {
 			if pth[base+1].index == nil {
@@ -228,7 +228,7 @@ func deleteJsonPathSlice(j []interface{}, pth JsonPath, base int) error {
 			j[*pth[base].index] = append(item[:*pth[base+1].index], item[*pth[base+1].index+1:])
 			return nil
 		}
-		return deleteJsonPathSlice(item, pth, base+1)
+		return deleteJSONPathSlice(item, pth, base+1)
 	default:
 		return fmt.Errorf("invalid non-terminal json path %q for index", pth[:base+1])
 	}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/validation.go

@@ -0,0 +1,119 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package objectmeta
+
+import (
+	"strings"
+
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	metavalidation "k8s.io/apimachinery/pkg/api/validation"
+	"k8s.io/apimachinery/pkg/api/validation/path"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	utilvalidation "k8s.io/apimachinery/pkg/util/validation"
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+// Validate validates embedded ObjectMeta and TypeMeta.
+// It also validate those at the root if includeRoot is true.
+func Validate(pth *field.Path, obj interface{}, s *structuralschema.Structural, includeRoot bool) field.ErrorList {
+	if includeRoot {
+		if s == nil {
+			s = &structuralschema.Structural{}
+		}
+		clone := *s
+		clone.XEmbeddedResource = true
+		s = &clone
+	}
+	return validate(pth, obj, s)
+}
+
+func validate(pth *field.Path, x interface{}, s *structuralschema.Structural) field.ErrorList {
+	if s == nil {
+		return nil
+	}
+
+	var allErrs field.ErrorList
+
+	switch x := x.(type) {
+	case map[string]interface{}:
+		if s.XEmbeddedResource {
+			allErrs = append(allErrs, validateEmbeddedResource(pth, x, s)...)
+		}
+
+		for k, v := range x {
+			prop, ok := s.Properties[k]
+			if ok {
+				allErrs = append(allErrs, validate(pth.Child(k), v, &prop)...)
+			} else if s.AdditionalProperties != nil {
+				allErrs = append(allErrs, validate(pth.Key(k), v, s.AdditionalProperties.Structural)...)
+			}
+		}
+	case []interface{}:
+		for i, v := range x {
+			allErrs = append(allErrs, validate(pth.Index(i), v, s.Items)...)
+		}
+	default:
+		// scalars, do nothing
+	}
+
+	return allErrs
+}
+
+func validateEmbeddedResource(pth *field.Path, x map[string]interface{}, s *structuralschema.Structural) field.ErrorList {
+	var allErrs field.ErrorList
+
+	// require apiVersion and kind, but not metadata
+	if _, found := x["apiVersion"]; !found {
+		allErrs = append(allErrs, field.Required(pth.Child("apiVersion"), "must not be empty"))
+	}
+	if _, found := x["kind"]; !found {
+		allErrs = append(allErrs, field.Required(pth.Child("kind"), "must not be empty"))
+	}
+
+	for k, v := range x {
+		switch k {
+		case "apiVersion":
+			if apiVersion, ok := v.(string); !ok {
+				allErrs = append(allErrs, field.Invalid(pth.Child("apiVersion"), v, "must be a string"))
+			} else if len(apiVersion) == 0 {
+				allErrs = append(allErrs, field.Invalid(pth.Child("apiVersion"), apiVersion, "must not be empty"))
+			} else if _, err := schema.ParseGroupVersion(apiVersion); err != nil {
+				allErrs = append(allErrs, field.Invalid(pth.Child("apiVersion"), apiVersion, err.Error()))
+			}
+		case "kind":
+			if kind, ok := v.(string); !ok {
+				allErrs = append(allErrs, field.Invalid(pth.Child("kind"), v, "must be a string"))
+			} else if len(kind) == 0 {
+				allErrs = append(allErrs, field.Invalid(pth.Child("kind"), kind, "must not be empty"))
+			} else if errs := utilvalidation.IsDNS1035Label(strings.ToLower(kind)); len(errs) > 0 {
+				allErrs = append(allErrs, field.Invalid(pth.Child("kind"), kind, "may have mixed case, but should otherwise match: "+strings.Join(errs, ",")))
+			}
+		case "metadata":
+			meta, _, err := GetObjectMeta(x, false)
+			if err != nil {
+				allErrs = append(allErrs, field.Invalid(pth.Child("metadata"), v, err.Error()))
+			} else {
+				if len(meta.Name) == 0 {
+					meta.Name = "fakename" // we have to set something to avoid an error
+				}
+				allErrs = append(allErrs, metavalidation.ValidateObjectMeta(meta, len(meta.Namespace) > 0, path.ValidatePathSegmentName, pth.Child("metadata"))...)
+			}
+		}
+	}
+
+	return allErrs
+}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/validation_test.go

@@ -0,0 +1,215 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package objectmeta
+
+import (
+	"testing"
+
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	"k8s.io/apimachinery/pkg/util/json"
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+func TestValidateEmbeddedResource(t *testing.T) {
+	tests := []struct {
+		name   string
+		object map[string]interface{}
+		errors []validationMatch
+	}{
+		{name: "empty", object: map[string]interface{}{}, errors: []validationMatch{
+			required("apiVersion"),
+			required("kind"),
+		}},
+		{name: "version and kind", object: map[string]interface{}{
+			"apiVersion": "foo/v1",
+			"kind":       "Foo",
+		}},
+		{name: "invalid kind", object: map[string]interface{}{
+			"apiVersion": "foo/v1",
+			"kind":       "foo.bar-com",
+		}, errors: []validationMatch{
+			invalid("kind"),
+		}},
+		{name: "no name", object: map[string]interface{}{
+			"apiVersion": "foo/v1",
+			"kind":       "Foo",
+			"metadata": map[string]interface{}{
+				"namespace": "kube-system",
+			},
+		}},
+		{name: "no namespace", object: map[string]interface{}{
+			"apiVersion": "foo/v1",
+			"kind":       "Foo",
+			"metadata": map[string]interface{}{
+				"name": "foo",
+			},
+		}},
+		{name: "invalid", object: map[string]interface{}{
+			"apiVersion": "foo/v1",
+			"kind":       "Foo",
+			"metadata": map[string]interface{}{
+				"name":      "..",
+				"namespace": "$$$",
+				"labels": map[string]interface{}{
+					"#": "#",
+				},
+				"annotations": map[string]interface{}{
+					"#": "#",
+				},
+			},
+		}, errors: []validationMatch{
+			invalid("metadata", "name"),
+			invalid("metadata", "namespace"),
+			invalid("metadata", "labels"),      // key
+			invalid("metadata", "labels"),      // value
+			invalid("metadata", "annotations"), // key
+		}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			schema := &structuralschema.Structural{Extensions: structuralschema.Extensions{XEmbeddedResource: true}}
+			errs := validateEmbeddedResource(nil, tt.object, schema)
+			seenErrs := make([]bool, len(errs))
+
+			for _, expectedError := range tt.errors {
+				found := false
+				for i, err := range errs {
+					if expectedError.matches(err) && !seenErrs[i] {
+						found = true
+						seenErrs[i] = true
+						break
+					}
+				}
+
+				if !found {
+					t.Errorf("expected %v at %v, got %v", expectedError.errorType, expectedError.path.String(), errs)
+				}
+			}
+
+			for i, seen := range seenErrs {
+				if !seen {
+					t.Errorf("unexpected error: %v", errs[i])
+				}
+			}
+		})
+	}
+}
+
+func TestValidate(t *testing.T) {
+	tests := []struct {
+		name        string
+		object      string
+		includeRoot bool
+		errors      []validationMatch
+	}{
+		{name: "empty", object: `{}`, errors: []validationMatch{}},
+		{name: "include root", object: `{}`, includeRoot: true, errors: []validationMatch{
+			required("apiVersion"),
+			required("kind"),
+		}},
+		{name: "embedded", object: `
+{
+  "embedded": {}
+}`, errors: []validationMatch{
+			required("embedded", "apiVersion"),
+			required("embedded", "kind"),
+		}},
+		{name: "nested", object: `
+{
+  "nested": {
+    "embedded": {}
+  }
+}`, errors: []validationMatch{
+			required("nested", "apiVersion"),
+			required("nested", "kind"),
+			required("nested", "embedded", "apiVersion"),
+			required("nested", "embedded", "kind"),
+		}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			schema := &structuralschema.Structural{
+				Properties: map[string]structuralschema.Structural{
+					"embedded": {Extensions: structuralschema.Extensions{XEmbeddedResource: true}},
+					"nested": {
+						Extensions: structuralschema.Extensions{XEmbeddedResource: true},
+						Properties: map[string]structuralschema.Structural{
+							"embedded": {Extensions: structuralschema.Extensions{XEmbeddedResource: true}},
+						},
+					},
+				},
+			}
+
+			var obj map[string]interface{}
+			if err := json.Unmarshal([]byte(tt.object), &obj); err != nil {
+				t.Fatal(err)
+			}
+
+			errs := Validate(nil, obj, schema, tt.includeRoot)
+			seenErrs := make([]bool, len(errs))
+
+			for _, expectedError := range tt.errors {
+				found := false
+				for i, err := range errs {
+					if expectedError.matches(err) && !seenErrs[i] {
+						found = true
+						seenErrs[i] = true
+						break
+					}
+				}
+
+				if !found {
+					t.Errorf("expected %v at %v, got %v", expectedError.errorType, expectedError.path.String(), errs)
+				}
+			}
+
+			for i, seen := range seenErrs {
+				if !seen {
+					t.Errorf("unexpected error: %v", errs[i])
+				}
+			}
+		})
+	}
+}
+
+type validationMatch struct {
+	path      *field.Path
+	errorType field.ErrorType
+}
+
+func required(path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...), errorType: field.ErrorTypeRequired}
+}
+func invalid(path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...), errorType: field.ErrorTypeInvalid}
+}
+func invalidIndex(index int, path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...).Index(index), errorType: field.ErrorTypeInvalid}
+}
+func unsupported(path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...), errorType: field.ErrorTypeNotSupported}
+}
+func immutable(path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...), errorType: field.ErrorTypeInvalid}
+}
+func forbidden(path ...string) validationMatch {
+	return validationMatch{path: field.NewPath(path[0], path[1:]...), errorType: field.ErrorTypeForbidden}
+}
+
+func (v validationMatch) matches(err *field.Error) bool {
+	return err.Type == v.errorType && err.Field == v.path.String()
+}