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// Copyright 2020 The gVisor 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 cli provides a CLI interface for a mutating Kubernetes webhook.
package cli
import (
"flag"
"fmt"
"net"
"net/http"
"os"
"strconv"
"strings"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/webhook/pkg/injector"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
k8snet "k8s.io/apimachinery/pkg/util/net"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
)
var (
address = flag.String("address", "", "The ip address the admission webhook serves on. If unspecified, a public address is selected automatically.")
port = flag.Int("port", 0, "The port the admission webhook serves on.")
podLabels = flag.String("pod-namespace-labels", "", "A comma-separated namespace label selector, the admission webhook will only take effect on pods in selected namespaces, e.g. `label1,label2`.")
)
// Main runs the webhook.
func Main() {
flag.Parse()
if err := run(); err != nil {
log.Warningf("%v", err)
os.Exit(1)
}
}
func run() error {
log.Infof("Starting %s\n", injector.Name)
// Create client config.
cfg, err := rest.InClusterConfig()
if err != nil {
return fmt.Errorf("create in cluster config: %w", err)
}
// Create clientset.
clientset, err := kubernetes.NewForConfig(cfg)
if err != nil {
return fmt.Errorf("create kubernetes client: %w", err)
}
if err := injector.CreateConfiguration(clientset, parsePodLabels()); err != nil {
return fmt.Errorf("create webhook configuration: %w", err)
}
if err := startWebhookHTTPS(clientset); err != nil {
return fmt.Errorf("start webhook https server: %w", err)
}
return nil
}
func parsePodLabels() *metav1.LabelSelector {
rv := &metav1.LabelSelector{}
for _, s := range strings.Split(*podLabels, ",") {
req := metav1.LabelSelectorRequirement{
Key: strings.TrimSpace(s),
Operator: "Exists",
}
rv.MatchExpressions = append(rv.MatchExpressions, req)
}
return rv
}
func startWebhookHTTPS(clientset kubernetes.Interface) error {
log.Infof("Starting HTTPS handler")
defer log.Infof("Stopping HTTPS handler")
if *address == "" {
ip, err := k8snet.ChooseHostInterface()
if err != nil {
return fmt.Errorf("select ip address: %w", err)
}
*address = ip.String()
}
mux := http.NewServeMux()
mux.Handle("/", http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
injector.Admit(w, r)
}))
server := &http.Server{
// Listen on all addresses.
Addr: net.JoinHostPort(*address, strconv.Itoa(*port)),
TLSConfig: injector.GetTLSConfig(),
Handler: mux,
}
if err := server.ListenAndServeTLS("", ""); err != http.ErrServerClosed {
return fmt.Errorf("start HTTPS handler: %w", err)
}
return nil
}
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