mirror of
https://github.com/ysoftdevs/imagepullsecret-injector.git
synced 2026-01-16 08:37:04 +01:00
Initial commit
This commit is contained in:
Martin Šalata
95
cmd/main.go
Normal file
95
cmd/main.go
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@@ -0,0 +1,95 @@
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package main
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import (
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"context"
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"crypto/tls"
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"flag"
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"fmt"
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"net/http"
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"os"
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"os/signal"
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"strconv"
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"syscall"
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"github.com/golang/glog"
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)
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func LookupStringEnv(envName string, defVal string) string {
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if envVal, exists := os.LookupEnv(envName); exists {
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return envVal
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}
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return defVal
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}
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func LookupBoolEnv(envName string, defVal bool) bool {
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if envVal, exists := os.LookupEnv(envName); exists {
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if boolVal, err := strconv.ParseBool(envVal); err == nil {
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return boolVal
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}
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}
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return defVal
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}
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func LookupIntEnv(envName string, defVal int) int {
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if envVal, exists := os.LookupEnv(envName); exists {
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if intVal, err := strconv.Atoi(envVal); err == nil {
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return intVal
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}
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}
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return defVal
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}
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func main() {
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parameters := DefaultParametersObject()
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// get command line parameters
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flag.IntVar(¶meters.port, "port", LookupIntEnv("CONFIG_PORT", parameters.port), "Webhook server port.")
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flag.StringVar(¶meters.certFile, "tlsCertFile", LookupStringEnv("CONFIG_CERT_PATH", parameters.certFile), "File containing the x509 Certificate for HTTPS.")
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flag.StringVar(¶meters.keyFile, "tlsKeyFile", LookupStringEnv("CONFIG_KEY_PATH", parameters.keyFile), "File containing the x509 private key to --tlsCertFile.")
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flag.StringVar(¶meters.excludeNamespaces, "excludeNamespaces", LookupStringEnv("CONFIG_EXCLUDE_NAMESPACES", parameters.excludeNamespaces), "Comma-separated namespace names to ignore.")
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flag.StringVar(¶meters.serviceAccounts, "serviceAccounts", LookupStringEnv("CONFIG_SERVICE_ACCOUNTS", parameters.serviceAccounts), "Comma-separated service account names to watch.")
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flag.StringVar(¶meters.sourceImagePullSecretName, "sourceImagePullSecretName", LookupStringEnv("CONFIG_SOURCE_IMAGE_PULL_SECRET_NAME", parameters.sourceImagePullSecretName), "Name of the imagePullSecret secret we use as source.")
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flag.StringVar(¶meters.sourceImagePullSecretNamespace, "sourceImagePullSecretNamespace", LookupStringEnv("CONFIG_SOURCE_IMAGE_PULL_SECRET_NAMESPACE", parameters.sourceImagePullSecretNamespace), "Namespace of the imagePullSecret secret we use as source.")
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flag.BoolVar(¶meters.allServiceAccounts, "allServiceAccounts", LookupBoolEnv("CONFIG_ALL_SERVICE_ACCOUNTS", parameters.allServiceAccounts), "Switch for watching all service accounts. If true, serviceAccounts parameter is ignored")
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flag.Parse()
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glog.Infof("Running with config: %+v", parameters)
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whsvr := &WebhookServer{
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config: ¶meters,
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server: &http.Server{
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Addr: fmt.Sprintf(":%v", parameters.port),
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// This is quite inefficient as it loads file contents on every TLS ClientHello, but ¯\_(ツ)_/¯
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TLSConfig: &tls.Config{GetCertificate: func(info *tls.ClientHelloInfo) (*tls.Certificate, error) {
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glog.Infof("Loading certificates")
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cert, err := tls.LoadX509KeyPair(parameters.certFile, parameters.keyFile)
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return &cert, err
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}},
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},
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}
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// define http server and server handler
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mux := http.NewServeMux()
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mux.HandleFunc("/mutate", whsvr.serve)
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whsvr.server.Handler = mux
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// start webhook server in new rountine
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go func() {
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if err := whsvr.server.ListenAndServeTLS(parameters.certFile, parameters.keyFile); err != nil {
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glog.Errorf("Failed to listen and serve webhook server: %v", err)
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}
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}()
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// listening OS shutdown singal
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signalChan := make(chan os.Signal, 1)
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signal.Notify(signalChan, syscall.SIGINT, syscall.SIGTERM)
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<-signalChan
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glog.Infof("Got OS shutdown signal, shutting down webhook server gracefully...")
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if err := whsvr.server.Shutdown(context.Background()); err != nil {
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glog.Errorf("Error while shutting down: %v", err)
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}
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}
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329
cmd/webhook.go
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329
cmd/webhook.go
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@@ -0,0 +1,329 @@
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package main
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"k8s.io/apimachinery/pkg/api/errors"
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"net/http"
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"os"
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"strings"
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"github.com/golang/glog"
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"k8s.io/api/admission/v1beta1"
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admissionregistrationv1beta1 "k8s.io/api/admissionregistration/v1beta1"
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"k8s.io/api/core/v1"
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corev1 "k8s.io/api/core/v1"
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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/serializer"
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"k8s.io/client-go/kubernetes"
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"k8s.io/client-go/rest"
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)
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var (
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runtimeScheme = runtime.NewScheme()
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codecs = serializer.NewCodecFactory(runtimeScheme)
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deserializer = codecs.UniversalDeserializer()
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)
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const (
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imagePullSecretName = "my-cool-secret"
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)
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type WebhookServer struct {
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server *http.Server
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config *WhSvrParameters
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}
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// Webhook Server parameters
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type WhSvrParameters struct {
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port int // webhook server port
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certFile string // path to the x509 certificate for https
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keyFile string // path to the x509 private key matching `CertFile`
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excludeNamespaces string
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serviceAccounts string
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allServiceAccounts bool
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sourceImagePullSecretName string
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sourceImagePullSecretNamespace string
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}
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var (
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defaultIgnoredNamespaces = []string{
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metav1.NamespaceSystem,
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metav1.NamespacePublic,
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}
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defaultServiceAccounts = []string{
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"default",
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}
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)
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func DefaultParametersObject() WhSvrParameters {
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return WhSvrParameters{
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port: 8443,
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certFile: "/etc/webhook/certs/cert.pem",
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keyFile: "/etc/webhook/certs/key.pem",
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excludeNamespaces: strings.Join(defaultIgnoredNamespaces, ","),
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serviceAccounts: strings.Join(defaultServiceAccounts, ","),
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allServiceAccounts: false,
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sourceImagePullSecretName: "my-cool-secret-source",
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sourceImagePullSecretNamespace: "default",
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}
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}
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type patchOperation struct {
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Op string `json:"op"`
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Path string `json:"path"`
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Value interface{} `json:"value,omitempty"`
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}
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func init() {
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_ = corev1.AddToScheme(runtimeScheme)
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_ = admissionregistrationv1beta1.AddToScheme(runtimeScheme)
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// defaulting with webhooks:
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// https://github.com/kubernetes/kubernetes/issues/57982
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_ = v1.AddToScheme(runtimeScheme)
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}
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func addImagePullSecret(target, added []corev1.LocalObjectReference, basePath string) (patch []patchOperation) {
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first := len(target) == 0
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var value interface{}
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for _, add := range added {
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value = add
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path := basePath
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if first {
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first = false
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value = []corev1.LocalObjectReference{add}
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} else {
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path = path + "/-"
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}
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patch = append(patch, patchOperation{
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Op: "add",
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Path: path,
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Value: value,
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})
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}
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return patch
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}
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func getCurrentNamespace() string {
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// This way assumes you've set the POD_NAMESPACE environment variable using the downward API.
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// This check has to be done first for backwards compatibility with the way InClusterConfig was originally set up
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if ns, ok := os.LookupEnv("POD_NAMESPACE"); ok {
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return ns
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}
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// Fall back to the namespace associated with the service account token, if available
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if data, err := ioutil.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); err == nil {
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if ns := strings.TrimSpace(string(data)); len(ns) > 0 {
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return ns
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}
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}
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return "default"
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}
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func (whsvr *WebhookServer) ensureSecrets(ar *v1beta1.AdmissionReview) error {
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glog.Infof("Ensuring existing secrets")
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namespace := ar.Request.Namespace
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config, err := rest.InClusterConfig()
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if err != nil {
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glog.Errorf("Could not create k8s client: %v", err)
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return err
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}
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clientset, err := kubernetes.NewForConfig(config)
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if err != nil {
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glog.Errorf("Could not create k8s clientset: %v", err)
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return err
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}
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currentNamespace := getCurrentNamespace()
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glog.Infof("Looking for the source secret")
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sourceSecret, err := clientset.CoreV1().Secrets(whsvr.config.sourceImagePullSecretNamespace).Get(whsvr.config.sourceImagePullSecretName, metav1.GetOptions{})
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if err != nil {
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glog.Errorf("Could not fetch source secret %s in namespace %s: %v", whsvr.config.sourceImagePullSecretName, currentNamespace, err)
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return err
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}
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glog.Infof("Source secret found")
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glog.Infof("Looking for the existing target secret")
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secret, err := clientset.CoreV1().Secrets(namespace).Get(imagePullSecretName, metav1.GetOptions{})
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if err != nil && !errors.IsNotFound(err) {
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glog.Errorf("Could not fetch secret %s in namespace %s: %v", imagePullSecretName, namespace, err)
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return err
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}
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if err != nil && errors.IsNotFound(err) {
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glog.Infof("Target secret not found, creating a new one")
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if _, createErr := clientset.CoreV1().Secrets(namespace).Create(&corev1.Secret{
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ObjectMeta: metav1.ObjectMeta{
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Name: imagePullSecretName,
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Namespace: namespace,
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},
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Data: sourceSecret.Data,
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Type: sourceSecret.Type,
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}); createErr != nil {
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glog.Errorf("Could not create secret %s in namespace %s: %v", imagePullSecretName, namespace, err)
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return err
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}
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glog.Infof("Target secret created successfully")
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return nil
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}
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glog.Infof("Target secret found, updating")
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secret.Data = sourceSecret.Data
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if _, err := clientset.CoreV1().Secrets(namespace).Update(secret); err != nil {
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glog.Errorf("Could not update secret %s in namespace %s: %v", imagePullSecretName, namespace, err)
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return err
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}
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glog.Infof("Target secret updated successfully")
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return nil
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}
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func (whsvr *WebhookServer) shouldMutate(sa corev1.ServiceAccount) bool {
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for _, excludedNamespace := range strings.Split(whsvr.config.excludeNamespaces, ",") {
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if sa.Namespace == excludedNamespace {
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return false
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}
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}
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if whsvr.config.allServiceAccounts {
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return true
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}
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for _, saName := range strings.Split(whsvr.config.serviceAccounts, ",") {
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if saName == sa.Name {
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return true
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}
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}
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return false
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}
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func (whsvr *WebhookServer) mutateServiceAccount(ar *v1beta1.AdmissionReview) *v1beta1.AdmissionResponse {
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req := ar.Request
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glog.Infof("Unmarshalling the ServiceAccount object from request")
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var sa corev1.ServiceAccount
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if err := json.Unmarshal(req.Object.Raw, &sa); err != nil {
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glog.Errorf("Could not unmarshal raw object: %v", err)
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return &v1beta1.AdmissionResponse{
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Result: &metav1.Status{
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Message: err.Error(),
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},
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}
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}
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glog.Infof("AdmissionReview for Kind=%v, Namespace=%v Name=%v (%v) UID=%v patchOperation=%v UserInfo=%v",
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req.Kind, req.Namespace, req.Name, sa.Name, req.UID, req.Operation, req.UserInfo)
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if !whsvr.shouldMutate(sa) {
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glog.Infof("Conditions for mutation not met, skipping")
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return &v1beta1.AdmissionResponse{
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Allowed: true,
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}
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}
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// Check whether we already have the imagePullSecretName present
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if sa.ImagePullSecrets != nil {
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glog.Infof("ServiceAccount is already in the correct state, skipping")
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for _, lor := range sa.ImagePullSecrets {
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if imagePullSecretName == lor.Name {
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return &v1beta1.AdmissionResponse{
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Allowed: true,
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}
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}
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}
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}
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glog.Infof("ServiceAccount is missing ImagePullSecrets configuration, creating a patch")
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var patch []patchOperation
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patch = append(patch, addImagePullSecret(sa.ImagePullSecrets, []corev1.LocalObjectReference{{Name: imagePullSecretName}}, "/imagePullSecrets")...)
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patchBytes, err := json.Marshal(patch)
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if err != nil {
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glog.Errorf("Could not marshal patch object: %v", err)
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return &v1beta1.AdmissionResponse{
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Result: &metav1.Status{
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Message: err.Error(),
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},
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}
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}
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if err := whsvr.ensureSecrets(ar); err != nil {
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glog.Errorf("Could not ensure existence of the imagePullSecret")
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return &v1beta1.AdmissionResponse{
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Result: &metav1.Status{
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Message: err.Error(),
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},
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}
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}
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return &v1beta1.AdmissionResponse{
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Allowed: true,
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Patch: patchBytes,
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PatchType: func() *v1beta1.PatchType {
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pt := v1beta1.PatchTypeJSONPatch
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return &pt
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}(),
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}
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}
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// Serve method for webhook server
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func (whsvr *WebhookServer) serve(w http.ResponseWriter, r *http.Request) {
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var body []byte
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if r.Body != nil {
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if data, err := ioutil.ReadAll(r.Body); err == nil {
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body = data
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}
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}
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if len(body) == 0 {
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glog.Error("empty body")
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http.Error(w, "empty body", http.StatusBadRequest)
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return
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}
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// verify the content type is accurate
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contentType := r.Header.Get("Content-Type")
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if contentType != "application/json" {
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glog.Errorf("Content-Type=%s, expect application/json", contentType)
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http.Error(w, "invalid Content-Type, expect `application/json`", http.StatusUnsupportedMediaType)
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return
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}
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var admissionResponse *v1beta1.AdmissionResponse
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ar := v1beta1.AdmissionReview{}
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if _, _, err := deserializer.Decode(body, nil, &ar); err != nil {
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glog.Errorf("Can't decode body: %v", err)
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admissionResponse = &v1beta1.AdmissionResponse{
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Result: &metav1.Status{
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Message: err.Error(),
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},
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}
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} else {
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admissionResponse = whsvr.mutateServiceAccount(&ar)
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}
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admissionReview := v1beta1.AdmissionReview{
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TypeMeta: metav1.TypeMeta{Kind: "AdmissionReview", APIVersion: "admission.k8s.io/v1"},
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}
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if admissionResponse != nil {
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admissionReview.Response = admissionResponse
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if ar.Request != nil {
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admissionReview.Response.UID = ar.Request.UID
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}
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}
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resp, err := json.Marshal(admissionReview)
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if err != nil {
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glog.Errorf("Can't encode response: %v", err)
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http.Error(w, fmt.Sprintf("could not encode response: %v", err), http.StatusInternalServerError)
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}
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glog.Infof("Ready to write reponse ...")
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if _, err := w.Write(resp); err != nil {
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glog.Errorf("Can't write response: %v", err)
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http.Error(w, fmt.Sprintf("could not write response: %v", err), http.StatusInternalServerError)
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}
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}
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