cluster/gce/gci/credential-provider: add barebones GCP credential provider for testing only

Signed-off-by: Andrew Sy Kim <andrewsy@google.com>
Co-authored-by: Aditi Sharma <adi.sky17@gmail.com>

cluster/gce/gci/credential-provider/main.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2022 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 main
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"time"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/klog/v2"
+	credentialproviderv1alpha1 "k8s.io/kubelet/pkg/apis/credentialprovider/v1alpha1"
+)
+
+func main() {
+	if err := getCredentials(os.Stdout); err != nil {
+		klog.Fatalf("failed to get credentials: %v", err)
+	}
+}
+
+func getCredentials(w io.Writer) error {
+	provider := &provider{
+		client: &http.Client{
+			Timeout: 10 * time.Second,
+		},
+	}
+
+	data, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		return err
+	}
+
+	var authRequest credentialproviderv1alpha1.CredentialProviderRequest
+	err = json.Unmarshal(data, &authRequest)
+	if err != nil {
+		return err
+	}
+
+	auth, err := provider.Provide(authRequest.Image)
+	if err != nil {
+		return err
+	}
+
+	response := &credentialproviderv1alpha1.CredentialProviderResponse{
+		TypeMeta: metav1.TypeMeta{
+			Kind:       "CredentialProviderResponse",
+			APIVersion: "credentialprovider.kubelet.k8s.io/v1alpha1",
+		},
+		CacheKeyType: credentialproviderv1alpha1.RegistryPluginCacheKeyType,
+		Auth:         auth,
+	}
+
+	if err := json.NewEncoder(w).Encode(response); err != nil {
+		// The error from json.Marshal is intentionally not included so as to not leak credentials into the logs
+		return errors.New("error marshaling response")
+	}
+
+	return nil
+}

cluster/gce/gci/credential-provider/provider.go

@@ -0,0 +1,122 @@
+/*
+Copyright 2022 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.
+*/
+
+// Originally copied from pkg/credentialproviders/gcp
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+
+	credentialproviderv1alpha1 "k8s.io/kubelet/pkg/apis/credentialprovider/v1alpha1"
+)
+
+const (
+	metadataToken = "http://metadata.google.internal./computeMetadata/v1/instance/service-accounts/default/token"
+	metadataEmail = "http://metadata.google.internal./computeMetadata/v1/instance/service-accounts/default/email"
+	maxReadLength = 10 * 1 << 20 // 10MB
+)
+
+var containerRegistryUrls = []string{"container.cloud.google.com", "gcr.io", "*.gcr.io", "*.pkg.dev"}
+
+// HTTPError wraps a non-StatusOK error code as an error.
+type HTTPError struct {
+	StatusCode int
+	URL        string
+}
+
+var _ error = &HTTPError{}
+
+// Error implements error
+func (h *HTTPError) Error() string {
+	return fmt.Sprintf("http status code: %d while fetching url %s",
+		h.StatusCode, h.URL)
+}
+
+// TokenBlob is used to decode the JSON blob containing an access token
+// that is returned by GCE metadata.
+type TokenBlob struct {
+	AccessToken string `json:"access_token"`
+}
+
+type provider struct {
+	client *http.Client
+}
+
+func (p *provider) Provide(image string) (map[string]credentialproviderv1alpha1.AuthConfig, error) {
+	cfg := map[string]credentialproviderv1alpha1.AuthConfig{}
+
+	tokenJSONBlob, err := readURL(p.tokenEndpoint, p.client)
+	if err != nil {
+		return cfg, err
+	}
+
+	var parsedBlob TokenBlob
+	if err := json.Unmarshal(tokenJSONBlob, &parsedBlob); err != nil {
+		return cfg, err
+	}
+
+	authConfig := credentialproviderv1alpha1.AuthConfig{
+		Username: "_token",
+		Password: parsedBlob.AccessToken,
+	}
+
+	// Add our entry for each of the supported container registry URLs
+	for _, k := range containerRegistryUrls {
+		cfg[k] = authConfig
+	}
+	return cfg, nil
+}
+
+func readURL(url string, client *http.Client) (body []byte, err error) {
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	rea.Header = &http.Header{
+		"Metadata-Flavor": []string{"Google"},
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, &HTTPError{
+			StatusCode: resp.StatusCode,
+			URL:        url,
+		}
+	}
+
+	limitedReader := &io.LimitedReader{R: resp.Body, N: maxReadLength}
+	contents, err := ioutil.ReadAll(limitedReader)
+	if err != nil {
+		return nil, err
+	}
+
+	if limitedReader.N <= 0 {
+		return nil, errors.New("the read limit is reached")
+	}
+
+	return contents, nil
+}

test/e2e_node/remote/node_e2e.go

@@ -106,10 +106,10 @@ func prependMemcgNotificationFlag(args string) string {
 // a credential provider plugin.
 func prependGCPCredentialProviderFlag(args, workspace string) string {
 	credentialProviderConfig := filepath.Join(workspace, "credential-provider.yaml")
-	disableIntreeCredentialProviderFlag := "--kubelet-flags=--feature-gates=DisableKubeletCloudCredentialProviders=true"
+	featureGateFlag := "--kubelet-flags=--feature-gates=DisableKubeletCloudCredentialProviders=true,KubeletCredentialProviders=true"
 	configFlag := fmt.Sprintf("--kubelet-flags=--image-credential-provider-config=%s", credentialProviderConfig)
 	binFlag := fmt.Sprintf("--kubelet-flags=--image-credential-provider-bin-dir=%s", workspace)
-	return fmt.Sprintf("%s %s %s %s", disableIntreeCredentialProviderFlag, configFlag, binFlag, args)
+	return fmt.Sprintf("%s %s %s %s", featureGateFlag, configFlag, binFlag, args)
 }
 
 // osSpecificActions takes OS specific actions required for the node tests

test/e2e_node/remote/utils.go

@@ -56,6 +56,8 @@ providers:
     matchImages:
     - "gcr.io"
     - "*.gcr.io"
+    - "container.cloud.google.com"
+    - "*.pkg.dev"
     defaultCacheDuration: 1m`
 
 // Install the cni plugin and add basic bridge configuration to the