Add HasOpenAPISchemaChanged to DiscoveryInterface

staging/src/k8s.io/client-go/applyconfigurations/meta/v1/unstructured.go

@@ -1,8 +1,6 @@
 package v1
 
 import (
-	"crypto/sha512"
-	"encoding/json"
 	"fmt"
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -32,40 +30,25 @@ type objectTypeCache interface {
 type nonCachingObjectTypeCache struct {
 	// TODO: lock this?
 	discoveryClient discovery.DiscoveryInterface
-	docHash         [sha512.Size]uint8
 	gvkParser       *fieldmanager.GvkParser
-	typeForGVK      map[schema.GroupVersionKind]*typed.ParseableType
 }
 
 // objectTypeForGVK retrieves the typed.ParseableType for a given gvk from the cache
 func (c *nonCachingObjectTypeCache) objectTypeForGVK(gvk schema.GroupVersionKind) (*typed.ParseableType, error) {
-	doc, err := c.discoveryClient.OpenAPISchema()
-	if err != nil {
-		return nil, err
-	}
 
-	docBytes, err := json.Marshal(doc)
+	if !c.discoveryClient.HasOpenAPISchemaChanged() && c.gvkParser != nil {
-	if err != nil {
+		// cache hit
-		return nil, err
-	}
-	docHash := sha512.Sum512(docBytes)
-
-	// cache hit
-	if c.docHash == docHash {
 		fmt.Println("cache hit")
-		fmt.Printf("docHash = %+v\n", docHash)
+		fmt.Printf("gvk = %+v\n", gvk)
-		objType, ok := c.typeForGVK[gvk]
+		return c.gvkParser.Type(gvk), nil
-		if ok {
-			fmt.Println("gvk recognized")
-			fmt.Printf("gvk = %+v\n", gvk)
-			return objType, nil
-		}
-		objType = c.gvkParser.Type(gvk)
-		c.typeForGVK[gvk] = objType
-		return objType, nil
 	} else {
-		fmt.Println("cache miss")
 		// cache miss
+		fmt.Println("cache miss")
+		fmt.Printf("gvk = %+v\n", gvk)
+		doc, err := c.discoveryClient.OpenAPISchema()
+		if err != nil {
+			return nil, err
+		}
 		models, err := proto.NewOpenAPIData(doc)
 		if err != nil {
 			return nil, err
@@ -77,11 +60,7 @@ func (c *nonCachingObjectTypeCache) objectTypeForGVK(gvk schema.GroupVersionKind
 		}
 
 		objType := gvkParser.Type(gvk)
-		c.docHash = docHash
 		c.gvkParser = gvkParser
-		c.typeForGVK = map[schema.GroupVersionKind]*typed.ParseableType{
-			gvk: objType,
-		}
 
 		return objType, nil
 	}

staging/src/k8s.io/client-go/discovery/cached/disk/cached_discovery.go

@@ -240,6 +240,10 @@ func (d *CachedDiscoveryClient) OpenAPISchema() (*openapi_v2.Document, error) {
 	return d.delegate.OpenAPISchema()
 }
 
+func (d *CachedDiscoveryClient) HasOpenAPISchemaChanged() bool {
+	return d.delegate.HasOpenAPISchemaChanged()
+}
+
 // Fresh is supposed to tell the caller whether or not to retry if the cache
 // fails to find something (false = retry, true = no need to retry).
 func (d *CachedDiscoveryClient) Fresh() bool {

staging/src/k8s.io/client-go/discovery/discovery_client.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"net/http"
 	"net/url"
 	"sort"
 	"strings"
@@ -125,6 +126,8 @@ type ServerVersionInterface interface {
 type OpenAPISchemaInterface interface {
 	// OpenAPISchema retrieves and parses the swagger API schema the server supports.
 	OpenAPISchema() (*openapi_v2.Document, error)
+
+	HasOpenAPISchemaChanged() bool
 }
 
 // DiscoveryClient implements the functions that discover server-supported API groups,
@@ -133,6 +136,7 @@ type DiscoveryClient struct {
 	restClient restclient.Interface
 
 	LegacyPrefix string
+	etag         string
 }
 
 // Convert metav1.APIVersions to metav1.APIGroup. APIVersions is used by legacy v1, so
@@ -419,9 +423,21 @@ func (d *DiscoveryClient) ServerVersion() (*version.Info, error) {
 	return &info, nil
 }
 
+func (d *DiscoveryClient) HasOpenAPISchemaChanged() bool {
+	result := d.restClient.Verb("HEAD").AbsPath("/openapi/v2").SetHeader("If-None-Match", d.etag).SetHeader("Accept", mimePb).Do(context.TODO())
+	var status int
+	result.StatusCode(&status)
+	if status == http.StatusNotModified {
+		return false
+	}
+	return true
+}
+
 // OpenAPISchema fetches the open api schema using a rest client and parses the proto.
 func (d *DiscoveryClient) OpenAPISchema() (*openapi_v2.Document, error) {
-	data, err := d.restClient.Get().AbsPath("/openapi/v2").SetHeader("Accept", mimePb).Do(context.TODO()).Raw()
+	result := d.restClient.Get().AbsPath("/openapi/v2").SetHeader("Accept", mimePb).Do(context.TODO())
+	d.etag = result.Etag()
+	data, err := result.Raw()
 	if err != nil {
 		if errors.IsForbidden(err) || errors.IsNotFound(err) || errors.IsNotAcceptable(err) {
 			// single endpoint not found/registered in old server, try to fetch old endpoint

staging/src/k8s.io/client-go/rest/request.go

@@ -1062,6 +1062,12 @@ func (r *Request) DoRaw(ctx context.Context) ([]byte, error) {
 
 // transformResponse converts an API response into a structured API object
 func (r *Request) transformResponse(resp *http.Response, req *http.Request) Result {
+	var etag string
+	etagHeader, ok := resp.Header["Etag"]
+	if ok && len(etagHeader) == 1 {
+		etag = etagHeader[0]
+	}
+
 	var body []byte
 	if resp.Body != nil {
 		data, err := ioutil.ReadAll(resp.Body)
@@ -1146,6 +1152,7 @@ func (r *Request) transformResponse(resp *http.Response, req *http.Request) Resu
 		statusCode:  resp.StatusCode,
 		decoder:     decoder,
 		warnings:    handleWarnings(resp.Header, r.warningHandler),
+		etag:        etag,
 	}
 }
 
@@ -1272,6 +1279,7 @@ type Result struct {
 	contentType string
 	err         error
 	statusCode  int
+	etag        string
 
 	decoder runtime.Decoder
 }
@@ -1308,6 +1316,10 @@ func (r Result) Get() (runtime.Object, error) {
 	return out, nil
 }
 
+func (r Result) Etag() string {
+	return r.etag
+}
+
 // StatusCode returns the HTTP status code of the request. (Only valid if no
 // error was returned.)
 func (r Result) StatusCode(statusCode *int) Result {