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main.go
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main.go
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// Copyright (c) 2023 Multus 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.
// This binary submit CSR for kube controll access for multus thin plugin
// and generate Kubeconfig
package main
import (
"encoding/base64"
"fmt"
"os"
"os/signal"
"syscall"
"text/template"
"time"
"github.com/spf13/pflag"
"gopkg.in/k8snetworkplumbingwg/multus-cni.v4/pkg/k8sclient"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/klog/v2"
)
var kubeConfigTemplate = `apiVersion: v1
clusters:
- cluster:
certificate-authority-data: {{.CADATA}}
server: {{.K8S_APISERVER}}
name: default-cluster
contexts:
- context:
cluster: default-cluster
namespace: default
user: default-auth
name: default-context
current-context: default-context
kind: Config
preferences: {}
users:
- name: default-auth
user:
client-certificate: {{.CERTDIR}}/multus-client-current.pem
client-key: {{.CERTDIR}}/multus-client-current.pem
`
func main() {
certDir := pflag.StringP("certdir", "", "/tmp", "specify cert directory")
bootstrapConfig := pflag.StringP("bootstrap-config", "", "/tmp/kubeconfig", "specify bootstrap kubernetes config")
kubeconfigPath := pflag.StringP("kubeconfig", "", "/run/multus/kubeconfig", "specify output kubeconfig path")
certDurationString := pflag.StringP("cert-duration", "", "10m", "specify certificate duration")
helpFlag := pflag.BoolP("help", "h", false, "show help message and quit")
pflag.Parse()
if *helpFlag {
pflag.PrintDefaults()
os.Exit(1)
}
// check variables
if _, err := os.Stat(*bootstrapConfig); err != nil {
klog.Fatalf("failed to read bootstrap config %q", *bootstrapConfig)
}
st, err := os.Stat(*certDir)
if err != nil {
klog.Fatalf("failed to find cert directory %q", *certDir)
}
if !st.IsDir() {
klog.Fatalf("cert directory %q is not directory", *certDir)
}
certDuration, err := time.ParseDuration(*certDurationString)
if err != nil {
klog.Fatalf("failed to parse duration %q: %v", *certDurationString, err)
}
nodeName := os.Getenv("MULTUS_NODE_NAME")
if nodeName == "" {
klog.Fatalf("cannot identify node name from MULTUS_NODE_NAME env variables")
}
// retrieve API server from bootstrapConfig()
config, err := clientcmd.BuildConfigFromFlags("", *bootstrapConfig)
if err != nil {
klog.Fatalf("cannot get in-cluster config: %v", err)
}
apiServer := fmt.Sprintf("%s%s", config.Host, config.APIPath)
caData := base64.StdEncoding.EncodeToString(config.CAData)
// run certManager to create certification
if _, err = k8sclient.PerNodeK8sClient(nodeName, *bootstrapConfig, certDuration, *certDir); err != nil {
klog.Fatalf("failed to start cert manager: %v", err)
}
fp, err := os.OpenFile(*kubeconfigPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
klog.Fatalf("cannot create kubeconfig file %q: %v", *kubeconfigPath, err)
}
// render kubeconfig
templateKubeconfig, err := template.New("kubeconfig").Parse(kubeConfigTemplate)
if err != nil {
klog.Fatalf("template parse error: %v", err)
}
templateData := map[string]string{
"CADATA": caData,
"CERTDIR": *certDir,
"K8S_APISERVER": apiServer,
}
// genearate kubeconfig from template
if err = templateKubeconfig.Execute(fp, templateData); err != nil {
klog.Fatalf("cannot create kubeconfig: %v", err)
}
if err = fp.Close(); err != nil {
klog.Fatalf("cannot save kubeconfig: %v", err)
}
klog.Infof("kubeconfig %q is saved", *kubeconfigPath)
// wait for signal
sigterm := make(chan os.Signal, 1)
signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM, syscall.SIGKILL)
<-sigterm
klog.Infof("signal received. remove kubeconfig %q and quit.", *kubeconfigPath)
err = os.Remove(*kubeconfigPath)
if err != nil {
klog.Errorf("failed to remove kubeconfig %q: %v", *kubeconfigPath, err)
}
}