234 lines
8.5 KiB
Go
234 lines
8.5 KiB
Go
// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
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// SPDX-License-Identifier: Apache-2.0
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// Package server is the command line entry point for pinniped-concierge.
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package server
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import (
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"context"
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"fmt"
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"io"
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"time"
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"github.com/spf13/cobra"
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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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genericapiserver "k8s.io/apiserver/pkg/server"
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genericoptions "k8s.io/apiserver/pkg/server/options"
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"go.pinniped.dev/internal/certauthority/dynamiccertauthority"
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"go.pinniped.dev/internal/concierge/apiserver"
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conciergescheme "go.pinniped.dev/internal/concierge/scheme"
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"go.pinniped.dev/internal/config/concierge"
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"go.pinniped.dev/internal/controller/authenticator/authncache"
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"go.pinniped.dev/internal/controllermanager"
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"go.pinniped.dev/internal/downward"
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"go.pinniped.dev/internal/dynamiccert"
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"go.pinniped.dev/internal/here"
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"go.pinniped.dev/internal/issuer"
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"go.pinniped.dev/internal/plog"
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"go.pinniped.dev/internal/registry/credentialrequest"
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)
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// App is an object that represents the pinniped-concierge application.
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type App struct {
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cmd *cobra.Command
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// CLI flags
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configPath string
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downwardAPIPath string
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}
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// New constructs a new App with command line args, stdout and stderr.
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func New(ctx context.Context, args []string, stdout, stderr io.Writer) *App {
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app := &App{}
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app.addServerCommand(ctx, args, stdout, stderr)
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return app
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}
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// Run the server.
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func (a *App) Run() error {
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return a.cmd.Execute()
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}
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// Create the server command and save it into the App.
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func (a *App) addServerCommand(ctx context.Context, args []string, stdout, stderr io.Writer) {
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cmd := &cobra.Command{
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Use: "pinniped-concierge",
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Long: here.Doc(`
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pinniped-concierge provides a generic API for mapping an external
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credential from somewhere to an internal credential to be used for
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authenticating to the Kubernetes API.`),
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RunE: func(cmd *cobra.Command, args []string) error { return a.runServer(ctx) },
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Args: cobra.NoArgs,
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}
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cmd.SetArgs(args)
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cmd.SetOut(stdout)
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cmd.SetErr(stderr)
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addCommandlineFlagsToCommand(cmd, a)
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a.cmd = cmd
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}
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// Define the app's commandline flags.
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func addCommandlineFlagsToCommand(cmd *cobra.Command, app *App) {
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cmd.Flags().StringVarP(
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&app.configPath,
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"config",
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"c",
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"pinniped.yaml",
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"path to configuration file",
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)
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cmd.Flags().StringVar(
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&app.downwardAPIPath,
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"downward-api-path",
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"/etc/podinfo",
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"path to Downward API volume mount",
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)
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plog.RemoveKlogGlobalFlags()
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}
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// Boot the aggregated API server, which will in turn boot the controllers.
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func (a *App) runServer(ctx context.Context) error {
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// Read the server config file.
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cfg, err := concierge.FromPath(a.configPath)
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if err != nil {
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return fmt.Errorf("could not load config: %w", err)
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}
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// Discover in which namespace we are installed.
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podInfo, err := downward.Load(a.downwardAPIPath)
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if err != nil {
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return fmt.Errorf("could not read pod metadata: %w", err)
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}
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// Initialize the cache of active authenticators.
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authenticators := authncache.New()
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// This cert provider will provide certs to the API server and will
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// be mutated by a controller to keep the certs up to date with what
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// is stored in a k8s Secret. Therefore it also effectively acting as
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// an in-memory cache of what is stored in the k8s Secret, helping to
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// keep incoming requests fast.
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dynamicServingCertProvider := dynamiccert.NewServingCert("concierge-serving-cert")
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// This cert provider will be used to provide the Kube signing key to the
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// cert issuer used to issue certs to Pinniped clients wishing to login.
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dynamicSigningCertProvider := dynamiccert.NewCA("concierge-kube-signing-cert")
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// This cert provider will be used to provide the impersonation proxy signing key to the
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// cert issuer used to issue certs to Pinniped clients wishing to login.
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impersonationProxySigningCertProvider := dynamiccert.NewCA("impersonation-proxy-signing-cert")
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// Get the "real" name of the login concierge API group (i.e., the API group name with the
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// injected suffix).
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scheme, loginGV, identityGV := conciergescheme.New(*cfg.APIGroupSuffix)
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// Prepare to start the controllers, but defer actually starting them until the
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// post start hook of the aggregated API server.
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startControllersFunc, err := controllermanager.PrepareControllers(
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&controllermanager.Config{
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ServerInstallationInfo: podInfo,
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APIGroupSuffix: *cfg.APIGroupSuffix,
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NamesConfig: &cfg.NamesConfig,
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Labels: cfg.Labels,
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KubeCertAgentConfig: &cfg.KubeCertAgentConfig,
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DiscoveryURLOverride: cfg.DiscoveryInfo.URL,
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DynamicServingCertProvider: dynamicServingCertProvider,
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DynamicSigningCertProvider: dynamicSigningCertProvider,
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ImpersonationSigningCertProvider: impersonationProxySigningCertProvider,
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ServingCertDuration: time.Duration(*cfg.APIConfig.ServingCertificateConfig.DurationSeconds) * time.Second,
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ServingCertRenewBefore: time.Duration(*cfg.APIConfig.ServingCertificateConfig.RenewBeforeSeconds) * time.Second,
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AuthenticatorCache: authenticators,
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},
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)
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if err != nil {
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return fmt.Errorf("could not prepare controllers: %w", err)
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}
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certIssuer := issuer.ClientCertIssuers{
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dynamiccertauthority.New(dynamicSigningCertProvider), // attempt to use the real Kube CA if possible
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dynamiccertauthority.New(impersonationProxySigningCertProvider), // fallback to our internal CA if we need to
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}
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// Get the aggregated API server config.
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aggregatedAPIServerConfig, err := getAggregatedAPIServerConfig(
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dynamicServingCertProvider,
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authenticators,
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certIssuer,
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startControllersFunc,
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*cfg.APIGroupSuffix,
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scheme,
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loginGV,
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identityGV,
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)
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if err != nil {
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return fmt.Errorf("could not configure aggregated API server: %w", err)
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}
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// Complete the aggregated API server config and make a server instance.
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server, err := aggregatedAPIServerConfig.Complete().New()
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if err != nil {
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return fmt.Errorf("could not create aggregated API server: %w", err)
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}
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// Run the server. Its post-start hook will start the controllers.
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return server.GenericAPIServer.PrepareRun().Run(ctx.Done())
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}
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// Create a configuration for the aggregated API server.
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func getAggregatedAPIServerConfig(
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dynamicCertProvider dynamiccert.Private,
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authenticator credentialrequest.TokenCredentialRequestAuthenticator,
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issuer issuer.ClientCertIssuer,
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startControllersPostStartHook func(context.Context),
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apiGroupSuffix string,
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scheme *runtime.Scheme,
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loginConciergeGroupVersion, identityConciergeGroupVersion schema.GroupVersion,
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) (*apiserver.Config, error) {
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codecs := serializer.NewCodecFactory(scheme)
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// this is unused for now but it is a safe value that we could use in the future
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defaultEtcdPathPrefix := fmt.Sprintf("/pinniped-concierge-registry/%s", apiGroupSuffix)
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recommendedOptions := genericoptions.NewRecommendedOptions(
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defaultEtcdPathPrefix,
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codecs.LegacyCodec(loginConciergeGroupVersion, identityConciergeGroupVersion),
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)
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recommendedOptions.Etcd = nil // turn off etcd storage because we don't need it yet
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recommendedOptions.SecureServing.ServerCert.GeneratedCert = dynamicCertProvider
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recommendedOptions.SecureServing.BindPort = 8443 // Don't run on default 443 because that requires root
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serverConfig := genericapiserver.NewRecommendedConfig(codecs)
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// Note that among other things, this ApplyTo() function copies
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// `recommendedOptions.SecureServing.ServerCert.GeneratedCert` into
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// `serverConfig.SecureServing.Cert` thus making `dynamicCertProvider`
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// the cert provider for the running server. The provider will be called
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// by the API machinery periodically. When the provider returns nil certs,
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// the API server will return "the server is currently unable to
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// handle the request" error responses for all incoming requests.
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// If the provider later starts returning certs, then the API server
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// will use them to handle the incoming requests successfully.
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if err := recommendedOptions.ApplyTo(serverConfig); err != nil {
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return nil, err
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}
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apiServerConfig := &apiserver.Config{
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GenericConfig: serverConfig,
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ExtraConfig: apiserver.ExtraConfig{
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Authenticator: authenticator,
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Issuer: issuer,
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StartControllersPostStartHook: startControllersPostStartHook,
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Scheme: scheme,
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NegotiatedSerializer: codecs,
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LoginConciergeGroupVersion: loginConciergeGroupVersion,
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IdentityConciergeGroupVersion: identityConciergeGroupVersion,
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},
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}
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return apiServerConfig, nil
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}
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