/*
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Copyright 2020 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package exec contains helper utilities for exec credential plugins.
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package exec
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import (
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"errors"
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"fmt"
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"os"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/apimachinery/pkg/runtime/serializer"
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utilruntime "k8s.io/apimachinery/pkg/util/runtime"
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"k8s.io/client-go/pkg/apis/clientauthentication"
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"k8s.io/client-go/pkg/apis/clientauthentication/v1alpha1"
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"k8s.io/client-go/pkg/apis/clientauthentication/v1beta1"
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"k8s.io/client-go/rest"
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)
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const execInfoEnv = "KUBERNETES_EXEC_INFO"
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var scheme = runtime.NewScheme()
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var codecs = serializer.NewCodecFactory(scheme)
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func init() {
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metav1.AddToGroupVersion(scheme, schema.GroupVersion{Version: "v1"})
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utilruntime.Must(v1alpha1.AddToScheme(scheme))
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utilruntime.Must(v1beta1.AddToScheme(scheme))
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utilruntime.Must(clientauthentication.AddToScheme(scheme))
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}
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// LoadExecCredentialFromEnv is a helper-wrapper around LoadExecCredential that loads from the
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// well-known KUBERNETES_EXEC_INFO environment variable.
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//
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// When the KUBERNETES_EXEC_INFO environment variable is not set or is empty, then this function
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// will immediately return an error.
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func LoadExecCredentialFromEnv() (runtime.Object, *rest.Config, error) {
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env := os.Getenv(execInfoEnv)
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if env == "" {
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return nil, nil, errors.New("KUBERNETES_EXEC_INFO env var is unset or empty")
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}
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return LoadExecCredential([]byte(env))
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}
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// LoadExecCredential loads the configuration needed for an exec plugin to communicate with a
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// cluster.
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//
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// LoadExecCredential expects the provided data to be a serialized client.authentication.k8s.io
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// ExecCredential object (of any version). If the provided data is invalid (i.e., it cannot be
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// unmarshalled into any known client.authentication.k8s.io ExecCredential version), an error will
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// be returned. A successfully unmarshalled ExecCredential will be returned as the first return
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// value.
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//
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// If the provided data is successfully unmarshalled, but it does not contain cluster information
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// (i.e., ExecCredential.Spec.Cluster == nil), then the returned rest.Config and error will be nil.
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//
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// Note that the returned rest.Config will use anonymous authentication, since the exec plugin has
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// not returned credentials for this cluster yet.
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func LoadExecCredential(data []byte) (runtime.Object, *rest.Config, error) {
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obj, gvk, err := codecs.UniversalDeserializer().Decode(data, nil, nil)
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if err != nil {
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return nil, nil, fmt.Errorf("decode: %w", err)
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}
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expectedGK := schema.GroupKind{
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Group: clientauthentication.SchemeGroupVersion.Group,
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Kind: "ExecCredential",
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}
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if gvk.GroupKind() != expectedGK {
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return nil, nil, fmt.Errorf(
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"invalid group/kind: wanted %s, got %s",
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expectedGK.String(),
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gvk.GroupKind().String(),
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)
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}
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// Explicitly convert object here so that we can return a nicer error message above for when the
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// data represents an invalid type.
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var execCredential clientauthentication.ExecCredential
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if err := scheme.Convert(obj, &execCredential, nil); err != nil {
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return nil, nil, fmt.Errorf("cannot convert to ExecCredential: %w", err)
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}
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if execCredential.Spec.Cluster == nil {
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return nil, nil, errors.New("ExecCredential does not contain cluster information")
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}
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restConfig, err := rest.ExecClusterToConfig(execCredential.Spec.Cluster)
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if err != nil {
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return nil, nil, fmt.Errorf("cannot create rest.Config: %w", err)
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}
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return obj, restConfig, nil
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}
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