Merge pull request #103564 from kevindelgado/unstr-extr-poc

ExtractItems for unstructured apply configurations

Kubernetes-commit: 0a704f9e1f6685f3ae39114435d23593a900e74c

applyconfigurations/meta/v1/unstructured.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2021 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 v1
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/managedfields"
+	"k8s.io/client-go/discovery"
+	"k8s.io/kube-openapi/pkg/util/proto"
+	"sigs.k8s.io/structured-merge-diff/v4/typed"
+)
+
+// openAPISchemaTTL is how frequently we need to check
+// whether the open API schema has changed or not.
+const openAPISchemaTTL = time.Minute
+
+// UnstructuredExtractor enables extracting the applied configuration state from object for fieldManager into an
+// unstructured object type.
+type UnstructuredExtractor interface {
+	Extract(object *unstructured.Unstructured, fieldManager string) (*unstructured.Unstructured, error)
+	ExtractStatus(object *unstructured.Unstructured, fieldManager string) (*unstructured.Unstructured, error)
+}
+
+// gvkParserCache caches the GVKParser in order to prevent from having to repeatedly
+// parse the models from the open API schema when the schema itself changes infrequently.
+type gvkParserCache struct {
+	// discoveryClient is the client for retrieving the openAPI document and checking
+	// whether the document has changed recently
+	discoveryClient discovery.DiscoveryInterface
+	// mu protects the gvkParser
+	mu sync.Mutex
+	// gvkParser retrieves the objectType for a given gvk
+	gvkParser *managedfields.GvkParser
+	// lastChecked is the last time we checked if the openAPI doc has changed.
+	lastChecked time.Time
+}
+
+// regenerateGVKParser builds the parser from the raw OpenAPI schema.
+func regenerateGVKParser(dc discovery.DiscoveryInterface) (*managedfields.GvkParser, error) {
+	doc, err := dc.OpenAPISchema()
+	if err != nil {
+		return nil, err
+	}
+
+	models, err := proto.NewOpenAPIData(doc)
+	if err != nil {
+		return nil, err
+	}
+
+	return managedfields.NewGVKParser(models, false)
+}
+
+// objectTypeForGVK retrieves the typed.ParseableType for a given gvk from the cache
+func (c *gvkParserCache) objectTypeForGVK(gvk schema.GroupVersionKind) (*typed.ParseableType, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	// if the ttl on the openAPISchema has expired,
+	// regenerate the gvk parser
+	if time.Since(c.lastChecked) > openAPISchemaTTL {
+		c.lastChecked = time.Now()
+		parser, err := regenerateGVKParser(c.discoveryClient)
+		if err != nil {
+			return nil, err
+		}
+		c.gvkParser = parser
+	}
+	return c.gvkParser.Type(gvk), nil
+}
+
+type extractor struct {
+	cache *gvkParserCache
+}
+
+// NewUnstructuredExtractor creates the extractor with which you can extract the applied configuration
+// for a given manager from an unstructured object.
+func NewUnstructuredExtractor(dc discovery.DiscoveryInterface) (UnstructuredExtractor, error) {
+	parser, err := regenerateGVKParser(dc)
+	if err != nil {
+		return nil, fmt.Errorf("failed generating initial GVK Parser: %v", err)
+	}
+	return &extractor{
+		cache: &gvkParserCache{
+			gvkParser:       parser,
+			discoveryClient: dc,
+		},
+	}, nil
+}
+
+// Extract extracts the applied configuration owned by fiieldManager from an unstructured object.
+// Note that the apply configuration itself is also an unstructured object.
+func (e *extractor) Extract(object *unstructured.Unstructured, fieldManager string) (*unstructured.Unstructured, error) {
+	return e.extractUnstructured(object, fieldManager, "")
+}
+
+// ExtractStatus is the same as ExtractUnstructured except
+// that it extracts the status subresource applied configuration.
+// Experimental!
+func (e *extractor) ExtractStatus(object *unstructured.Unstructured, fieldManager string) (*unstructured.Unstructured, error) {
+	return e.extractUnstructured(object, fieldManager, "status")
+}
+
+func (e *extractor) extractUnstructured(object *unstructured.Unstructured, fieldManager string, subresource string) (*unstructured.Unstructured, error) {
+	gvk := object.GetObjectKind().GroupVersionKind()
+	objectType, err := e.cache.objectTypeForGVK(gvk)
+	if err != nil {
+		return nil, fmt.Errorf("failed to fetch the objectType: %v", err)
+	}
+	result := &unstructured.Unstructured{}
+	err = managedfields.ExtractInto(object, *objectType, fieldManager, result, subresource)
+	if err != nil {
+		return nil, fmt.Errorf("failed calling ExtractInto for unstructured: %v", err)
+	}
+	result.SetName(object.GetName())
+	result.SetNamespace(object.GetNamespace())
+	result.SetKind(object.GetKind())
+	result.SetAPIVersion(object.GetAPIVersion())
+	return result, nil
+}

go.mod

@@ -31,8 +31,9 @@ require (
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac
 	google.golang.org/protobuf v1.26.0
 	k8s.io/api v0.0.0-20210720141931-aa30bdaf750c
-	k8s.io/apimachinery v0.0.0-20210712060818-a644435e2c13
+	k8s.io/apimachinery v0.0.0-20210805051055-f7769293e6f1
 	k8s.io/klog/v2 v2.9.0
+	k8s.io/kube-openapi v0.0.0-20210421082810-95288971da7e
 	k8s.io/utils v0.0.0-20210707171843-4b05e18ac7d9
 	sigs.k8s.io/structured-merge-diff/v4 v4.1.2
 	sigs.k8s.io/yaml v1.2.0
@@ -40,5 +41,5 @@ require (
 
 replace (
 	k8s.io/api => k8s.io/api v0.0.0-20210720141931-aa30bdaf750c
-	k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20210712060818-a644435e2c13
+	k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20210805051055-f7769293e6f1
 )

go.sum

@@ -446,8 +446,8 @@ honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt
 honnef.co/go/tools v0.0.1-2020.1.3/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
 k8s.io/api v0.0.0-20210720141931-aa30bdaf750c h1:bQDI22QyjupmAGqhbVE2uIkAkAAVEVfTf/n8RG/Xtpo=
 k8s.io/api v0.0.0-20210720141931-aa30bdaf750c/go.mod h1:FtqZiusVhnyM5jUPPFkDCU91OKo0sOpX9b9hotVGbIk=
-k8s.io/apimachinery v0.0.0-20210712060818-a644435e2c13 h1:Y40e5ho6n8KOvBCqdz/jm7ssKQyQLQdbZbC3lR9TaCU=
-k8s.io/apimachinery v0.0.0-20210712060818-a644435e2c13/go.mod h1:O3oNtNadZdeOMxHFVxOreoznohCpy0z6mocxbZr7oJ0=
+k8s.io/apimachinery v0.0.0-20210805051055-f7769293e6f1 h1:cVpwhaGeh/tNPBeYbFff3tjx5AxwG5zwImhz+eusG3k=
+k8s.io/apimachinery v0.0.0-20210805051055-f7769293e6f1/go.mod h1:O3oNtNadZdeOMxHFVxOreoznohCpy0z6mocxbZr7oJ0=
 k8s.io/gengo v0.0.0-20200413195148-3a45101e95ac/go.mod h1:ezvh/TsK7cY6rbqRK0oQQ8IAqLxYwwyPxAX1Pzy0ii0=
 k8s.io/klog/v2 v2.0.0/go.mod h1:PBfzABfn139FHAV07az/IF9Wp1bkk3vpT2XSJ76fSDE=
 k8s.io/klog/v2 v2.9.0 h1:D7HV+n1V57XeZ0m6tdRkfknthUaM06VFbWldOFh8kzM=