feat: support dev docker in docker (dind)

README.md

@@ -251,9 +251,10 @@ dns service ok
 Hello world!%
 ```
 
-### 本地进入开发模式
+### Dev mode in local
 
-将 Kubernetes pod 运行在本地的 Docker 容器中，同时配合 service mesh, 拦截带有制定 header 的流量到本地，或者所有的流量到本地
+Run the Kubernetes pod in the local Docker container, and cooperate with the service mesh to intercept the traffic with
+the specified header to the local, or all the traffic to the local.
 
 ```shell
 ➜  ~ kubevpn dev deployment/authors -n kube-system --headers a=1 -p 9080:9080 -p 80:80
@@ -323,6 +324,131 @@ de9e2f8ab57d        nginx:latest            "/docker-entrypoint.…"   5 seconds
 ➜  ~
 ```
 
+If you want to specify the image to start the container locally, you can use the parameter `--docker-image`. When the
+image does not exist locally, it will be pulled from the corresponding mirror warehouse. If you want to specify startup
+parameters, you can use `--entrypoint` parameter, replace it with the command you want to execute, such
+as `--entrypoint "tail -f /dev/null"`, for more parameters, see `kubevpn dev --help`.
+
+Notice:
+***If you want to start the development mode locally using Docker in Docker (DinD), since the program will read and
+write the `/tmp` directory, you need to manually add the parameter `-v /tmp:/tmp` (outer docker) and other thing is you
+need to special
+parameter `--parent-container` (inner docker) for sharing network and pid ***
+
+Example:
+
+```shell
+docker run -it --privileged -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp -v /Users/naison/.kube/config:/root/.kube/config naison/kubevpn:v1.1.21
+```
+
+```shell
+➜  ~ docker run -it --privileged -c authors -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp -v /Users/naison/.kube/vke:/root/.kube/config -v /Users/naison/Desktop/kubevpn/bin:/app naison/kubevpn:v1.1.21
+root@4d0c3c4eae2b:/# hostname
+4d0c3c4eae2b
+root@4d0c3c4eae2b:/# kubevpn dev deployment/authors -n kube-system --image naison/kubevpn:v1.1.21 --headers user=naison --parent-container 4d0c3c4eae2b --entrypoint "tail -f /dev/null"
+
+----------------------------------------------------------------------------------
+    Warn: Use sudo to execute command kubevpn can not use user env KUBECONFIG.
+    Because of sudo user env and user env are different.
+    Current env KUBECONFIG value:
+----------------------------------------------------------------------------------
+
+got cidr from cache
+traffic manager not exist, try to create it...
+pod [kubevpn-traffic-manager] status is Pending
+Container Reason Message
+
+pod [kubevpn-traffic-manager] status is Pending
+Container     Reason            Message
+control-plane ContainerCreating
+vpn           ContainerCreating
+webhook       ContainerCreating
+
+pod [kubevpn-traffic-manager] status is Running
+Container     Reason           Message
+control-plane ContainerRunning
+vpn           ContainerRunning
+webhook       ContainerRunning
+
+update ref count successfully
+Waiting for deployment "authors" rollout to finish: 1 old replicas are pending termination...
+Waiting for deployment "authors" rollout to finish: 1 old replicas are pending termination...
+deployment "authors" successfully rolled out
+port forward ready
+tunnel connected
+dns service ok
+tar: removing leading '/' from member names
+/tmp/3122262358661539581:/var/run/secrets/kubernetes.io/serviceaccount
+tar: Removing leading `/' from member names
+tar: Removing leading `/' from hard link targets
+/tmp/7677066538742627822:/var/run/secrets/kubernetes.io/serviceaccount
+latest: Pulling from naison/authors
+Digest: sha256:2e7b2d6a4c6143cde888fcdb70ba091d533e11de70e13e151adff7510a5d52d4
+Status: Downloaded newer image for naison/authors:latest
+Created container: authors_kube-system_kubevpn_c68e4
+Wait container authors_kube-system_kubevpn_c68e4 to be running...
+Container authors_kube-system_kubevpn_c68e4 is running now
+Created container: nginx_kube-system_kubevpn_c68e7
+Wait container nginx_kube-system_kubevpn_c68e7 to be running...
+Container nginx_kube-system_kubevpn_c68e7 is running now
+/opt/microservices # ps -ef
+PID   USER     TIME  COMMAND
+    1 root      0:00 {bash} /usr/bin/qemu-x86_64 /bin/bash /bin/bash
+   60 root      0:07 {kubevpn} /usr/bin/qemu-x86_64 kubevpn kubevpn dev deployment/authors -n kube-system --image naison/kubevpn:v1.1.21 --headers user=naison --parent
+   73 root      0:00 {tail} /usr/bin/qemu-x86_64 /usr/bin/tail tail -f /dev/null
+   80 root      0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+   92 root      0:00 {sh} /usr/bin/qemu-x86_64 /bin/sh /bin/sh
+  156 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  158 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  160 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  162 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  164 root      0:00 ps -ef
+/opt/microservices # ls
+app
+/opt/microservices # apk add curl
+fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
+fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
+(1/4) Installing brotli-libs (1.0.9-r5)
+(2/4) Installing nghttp2-libs (1.43.0-r0)
+(3/4) Installing libcurl (7.79.1-r5)
+(4/4) Installing curl (7.79.1-r5)
+Executing busybox-1.33.1-r3.trigger
+OK: 8 MiB in 19 packages
+/opt/microservices # curl localhost:80
+<!DOCTYPE html>
+<html>
+<head>
+<title>Welcome to nginx!</title>
+<style>
+html { color-scheme: light dark; }
+body { width: 35em; margin: 0 auto;
+font-family: Tahoma, Verdana, Arial, sans-serif; }
+</style>
+</head>
+<body>
+<h1>Welcome to nginx!</h1>
+<p>If you see this page, the nginx web server is successfully installed and
+working. Further configuration is required.</p>
+
+<p>For online documentation and support please refer to
+<a href="http://nginx.org/">nginx.org</a>.<br/>
+Commercial support is available at
+<a href="http://nginx.com/">nginx.com</a>.</p>
+
+<p><em>Thank you for using nginx.</em></p>
+</body>
+</html>
+/opt/microservices # ls
+app
+/opt/microservices # exit
+prepare to exit, cleaning up
+update ref count successfully
+ref-count is zero, prepare to clean up resource
+clean up successful
+root@4d0c3c4eae2b:/# exit
+exit
+```
+
 ### Multiple Protocol
 
 - TCP

README_ZH.md

@@ -251,7 +251,7 @@ Hello world!%
 
 ### 本地进入开发模式
 
-将 Kubernetes pod 运行在本地的 Docker 容器中，同时配合 service mesh, 拦截带有制定 header 的流量到本地，或者所有的流量到本地
+将 Kubernetes pod 运行在本地的 Docker 容器中，同时配合 service mesh, 拦截带有制定 header 的流量到本地，或者所有的流量到本地。这个开发模式依赖于本地 Docker .
 
 ```shell
 ➜  ~ kubevpn dev deployment/authors -n kube-system --headers a=1 -p 9080:9080 -p 80:80
@@ -319,6 +319,127 @@ de9e2f8ab57d        nginx:latest            "/docker-entrypoint.…"   5 seconds
 ➜  ~
 ```
 
+如果你想指定在本地启动容器的镜像, 可以使用参数 `--docker-image`, 当本地不存在该镜像时, 会从对应的镜像仓库拉取。如果你想指定启动参数，可以使用 `--entrypoint`
+参数，替换为你想要执行的命令，比如 `--entrypoint "tail -f /dev/null"`, 更多使用参数，请参见 `kubevpn dev --help`.
+
+注意：
+***如果你想在本地使用 Docker in Docker (DinD) 的方式启动开发模式, 由于程序会读写 `/tmp` 目录，您需要手动添加参数 `-v /tmp:/tmp`, 还有一点需要注意, 如果使用 DinD
+模式，为了共享容器网络和 pid, 还需要指定参数 `--parent-container` ***
+
+例如:
+
+```shell
+docker run -it --privileged -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp -v /Users/naison/.kube/config:/root/.kube/config naison/kubevpn:v1.1.21
+```
+
+```shell
+➜  ~ docker run -it --privileged -c authors -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp -v /Users/naison/.kube/config:/root/.kube/config naison/kubevpn:v1.1.21
+root@4d0c3c4eae2b:/# hostname
+4d0c3c4eae2b
+root@4d0c3c4eae2b:/# kubevpn dev deployment/authors -n kube-system --image naison/kubevpn:v1.1.21 --headers user=naison --parent-container 4d0c3c4eae2b --entrypoint "tail -f /dev/null"
+
+----------------------------------------------------------------------------------
+    Warn: Use sudo to execute command kubevpn can not use user env KUBECONFIG.
+    Because of sudo user env and user env are different.
+    Current env KUBECONFIG value:
+----------------------------------------------------------------------------------
+
+got cidr from cache
+traffic manager not exist, try to create it...
+pod [kubevpn-traffic-manager] status is Pending
+Container Reason Message
+
+pod [kubevpn-traffic-manager] status is Pending
+Container     Reason            Message
+control-plane ContainerCreating
+vpn           ContainerCreating
+webhook       ContainerCreating
+
+pod [kubevpn-traffic-manager] status is Running
+Container     Reason           Message
+control-plane ContainerRunning
+vpn           ContainerRunning
+webhook       ContainerRunning
+
+update ref count successfully
+Waiting for deployment "authors" rollout to finish: 1 old replicas are pending termination...
+Waiting for deployment "authors" rollout to finish: 1 old replicas are pending termination...
+deployment "authors" successfully rolled out
+port forward ready
+tunnel connected
+dns service ok
+tar: removing leading '/' from member names
+/tmp/3122262358661539581:/var/run/secrets/kubernetes.io/serviceaccount
+tar: Removing leading `/' from member names
+tar: Removing leading `/' from hard link targets
+/tmp/7677066538742627822:/var/run/secrets/kubernetes.io/serviceaccount
+latest: Pulling from naison/authors
+Digest: sha256:2e7b2d6a4c6143cde888fcdb70ba091d533e11de70e13e151adff7510a5d52d4
+Status: Downloaded newer image for naison/authors:latest
+Created container: authors_kube-system_kubevpn_c68e4
+Wait container authors_kube-system_kubevpn_c68e4 to be running...
+Container authors_kube-system_kubevpn_c68e4 is running now
+Created container: nginx_kube-system_kubevpn_c68e7
+Wait container nginx_kube-system_kubevpn_c68e7 to be running...
+Container nginx_kube-system_kubevpn_c68e7 is running now
+/opt/microservices # ps -ef
+PID   USER     TIME  COMMAND
+    1 root      0:00 {bash} /usr/bin/qemu-x86_64 /bin/bash /bin/bash
+   60 root      0:07 {kubevpn} /usr/bin/qemu-x86_64 kubevpn kubevpn dev deployment/authors -n kube-system --image naison/kubevpn:v1.1.21 --headers user=naison --parent
+   73 root      0:00 {tail} /usr/bin/qemu-x86_64 /usr/bin/tail tail -f /dev/null
+   80 root      0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+   92 root      0:00 {sh} /usr/bin/qemu-x86_64 /bin/sh /bin/sh
+  156 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  158 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  160 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  162 101       0:00 {nginx} /usr/bin/qemu-x86_64 /usr/sbin/nginx nginx -g daemon off;
+  164 root      0:00 ps -ef
+/opt/microservices # ls
+app
+/opt/microservices # apk add curl
+fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
+fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
+(1/4) Installing brotli-libs (1.0.9-r5)
+(2/4) Installing nghttp2-libs (1.43.0-r0)
+(3/4) Installing libcurl (7.79.1-r5)
+(4/4) Installing curl (7.79.1-r5)
+Executing busybox-1.33.1-r3.trigger
+OK: 8 MiB in 19 packages
+/opt/microservices # curl localhost:80
+<!DOCTYPE html>
+<html>
+<head>
+<title>Welcome to nginx!</title>
+<style>
+html { color-scheme: light dark; }
+body { width: 35em; margin: 0 auto;
+font-family: Tahoma, Verdana, Arial, sans-serif; }
+</style>
+</head>
+<body>
+<h1>Welcome to nginx!</h1>
+<p>If you see this page, the nginx web server is successfully installed and
+working. Further configuration is required.</p>
+
+<p>For online documentation and support please refer to
+<a href="http://nginx.org/">nginx.org</a>.<br/>
+Commercial support is available at
+<a href="http://nginx.com/">nginx.com</a>.</p>
+
+<p><em>Thank you for using nginx.</em></p>
+</body>
+</html>
+/opt/microservices # ls
+app
+/opt/microservices # exit
+prepare to exit, cleaning up
+update ref count successfully
+ref-count is zero, prepare to clean up resource
+clean up successful
+root@4d0c3c4eae2b:/# exit
+exit
+```
+
 ### 支持多种协议
 
 - TCP

cmd/kubevpn/cmds/dev.go

@@ -2,6 +2,7 @@ package cmds
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -9,6 +10,7 @@ import (
 
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/opts"
+	"github.com/docker/docker/api/types"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 	"k8s.io/client-go/util/retry"
@@ -68,6 +70,24 @@ func CmdDev(f cmdutil.Factory) *cobra.Command {
 				Workloads: []string{devOptions.Workload},
 			}
 
+			if devOptions.ParentContainer != "" {
+				client, _, err := dev.GetClient()
+				if err != nil {
+					return err
+				}
+				var inspect types.ContainerJSON
+				inspect, err = client.ContainerInspect(context.Background(), devOptions.ParentContainer)
+				if err != nil {
+					return err
+				}
+				if inspect.State == nil {
+					return fmt.Errorf("can not get container status, please make contianer name is valid")
+				}
+				if !inspect.State.Running {
+					return fmt.Errorf("container %s status is %s, expect is running, please make sure your outer docker name is correct", devOptions.ParentContainer, inspect.State.Status)
+				}
+			}
+
 			if err := connect.InitClient(f); err != nil {
 				return err
 			}
@@ -123,6 +143,7 @@ func CmdDev(f cmdutil.Factory) *cobra.Command {
 
 	// docker options
 	cmd.Flags().Var(&devOptions.ExtraHosts, "add-host", "Add a custom host-to-IP mapping (host:ip)")
+	cmd.Flags().StringVar(&devOptions.ParentContainer, "parent-container", "", "Parent container name if running in Docker (Docker in Docker)")
 	cmd.Flags().VarP(&devOptions.Volumes, "volume", "v", "Bind mount a volume")
 	cmd.Flags().Var(&devOptions.Mounts, "mount", "Attach a filesystem mount to the container")
 	cmd.Flags().Var(&devOptions.Expose, "expose", "Expose a port or a range of ports")

pkg/dev/convert.go

@@ -211,24 +211,27 @@ func GetVolume(ctx context.Context, f util.Factory, ns, pod string) (map[string]
 			if volumeMount.MountPath == "/tmp" {
 				continue
 			}
-
 			join := filepath.Join(os.TempDir(), strconv.Itoa(rand.Int()))
 			err = os.MkdirAll(join, 0755)
 			if err != nil {
 				return nil, err
 			}
+			if volumeMount.SubPath != "" {
+				join = filepath.Join(join, volumeMount.SubPath)
+			}
 			// pod-namespace/pod-name:path
 			remotePath := fmt.Sprintf("%s/%s:%s", ns, pod, volumeMount.MountPath)
 			stdIn, stdOut, stdErr := dockerterm.StdStreams()
 			copyOptions := cp.NewCopyOptions(genericclioptions.IOStreams{In: stdIn, Out: stdOut, ErrOut: stdErr})
 			copyOptions.Container = c.Name
+			copyOptions.MaxTries = 10
 			err = copyOptions.Complete(f, &cobra.Command{}, []string{remotePath, join})
 			if err != nil {
 				return nil, err
 			}
 			err = copyOptions.Run()
 			if err != nil {
-				_, _ = fmt.Fprintf(os.Stderr, "Can not download volume %s path %s, ignore...", volumeMount.Name, volumeMount.MountPath)
+				_, _ = fmt.Fprintf(os.Stderr, "Can not download volume %s path %s, err: %v, ignore...\n", volumeMount.Name, volumeMount.MountPath, err)
 				continue
 			}
 			m = append(m, mount.Mount{

pkg/dev/main.go

@@ -35,16 +35,17 @@ type Options struct {
 	// docker options
 	Platform string
 	//Pull         string // always, missing, never
-	PublishAll   bool
+	PublishAll      bool
-	Entrypoint   string
+	Entrypoint      string
-	DockerImage  string
+	DockerImage     string
-	Publish      opts.ListOpts
+	Publish         opts.ListOpts
-	Expose       opts.ListOpts
+	Expose          opts.ListOpts
-	ExtraHosts   opts.ListOpts
+	ExtraHosts      opts.ListOpts
-	Env          opts.ListOpts
+	ParentContainer string
-	Mounts       opts.MountOpt
+	Env             opts.ListOpts
-	Volumes      opts.ListOpts
+	Mounts          opts.MountOpt
-	VolumeDriver string
+	Volumes         opts.ListOpts
+	VolumeDriver    string
 }
 
 func (d Options) Main(ctx context.Context) error {
@@ -103,21 +104,42 @@ func (d Options) Main(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
+	var dockerCli *command.DockerCli
+	_, dockerCli, err = GetClient()
+	if err != nil {
+		return err
+	}
+	if d.ParentContainer != "" {
+		for _, config := range list[:] {
+			// remove expose port
+			config.config.ExposedPorts = nil
+			config.hostConfig.NetworkMode = containertypes.NetworkMode("container:" + d.ParentContainer)
+			config.hostConfig.PidMode = containertypes.PidMode("container:" + d.ParentContainer)
+			config.hostConfig.PortBindings = nil
 
-	// skip first
+			// remove dns
-	for _, config := range list[1:] {
+			config.hostConfig.DNS = nil
-		// remove expose port
+			config.hostConfig.DNSOptions = nil
-		config.config.ExposedPorts = nil
+			config.hostConfig.DNSSearch = nil
-		config.hostConfig.NetworkMode = containertypes.NetworkMode("container:" + list[0].containerName)
+			config.hostConfig.PublishAllPorts = false
-		config.hostConfig.PidMode = containertypes.PidMode("container:" + list[0].containerName)
+			config.config.Hostname = ""
-		config.hostConfig.PortBindings = nil
+		}
+	} else {
+		// skip first
+		for _, config := range list[1:] {
+			// remove expose port
+			config.config.ExposedPorts = nil
+			config.hostConfig.NetworkMode = containertypes.NetworkMode("container:" + list[0].containerName)
+			config.hostConfig.PidMode = containertypes.PidMode("container:" + list[0].containerName)
+			config.hostConfig.PortBindings = nil
 
-		// remove dns
+			// remove dns
-		config.hostConfig.DNS = nil
+			config.hostConfig.DNS = nil
-		config.hostConfig.DNSOptions = nil
+			config.hostConfig.DNSOptions = nil
-		config.hostConfig.DNSSearch = nil
+			config.hostConfig.DNSSearch = nil
-		config.hostConfig.PublishAllPorts = false
+			config.hostConfig.PublishAllPorts = false
-		config.config.Hostname = ""
+			config.config.Hostname = ""
+		}
 	}
 
 	handler.RollbackFuncList = append(handler.RollbackFuncList, func() {
@@ -127,11 +149,7 @@ func (d Options) Main(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
-	_, cli, err := GetClient()
+	return terminal(list[0].containerName, dockerCli)
-	if err != nil {
-		return err
-	}
-	return terminal(list[0].containerName, cli)
 }
 
 type Run []*RunConfig

pkg/dev/run.go

@@ -50,7 +50,7 @@ func run(ctx context.Context, runConfig *RunConfig, cli *client.Client) (err err
 		}
 		readCloser, err = cli.ImagePull(ctx, config.Image, types.ImagePullOptions{Platform: plat})
 		if err != nil {
-			return err
+			return fmt.Errorf("can not pull image %s, err: %s, please make sure image is exist and can be pulled from local", config.Image, err)
 		}
 		defer readCloser.Close()
 		_, stdout, _ := dockerterm.StdStreams()
@@ -64,7 +64,7 @@ func run(ctx context.Context, runConfig *RunConfig, cli *client.Client) (err err
 	var create typescommand.CreateResponse
 	create, err = cli.ContainerCreate(ctx, config, hostConfig, networkConfig, platform, name)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create container %s, err: %s", name, err)
 	}
 
 	log.Infof("Created container: %s", name)

pkg/dns/dns_linux.go

@@ -4,9 +4,14 @@
 package dns
 
 import (
+	"bytes"
+	"fmt"
 	"os"
 	"os/exec"
+	"path/filepath"
+	"strings"
 
+	"github.com/docker/docker/libnetwork/resolvconf"
 	miekgdns "github.com/miekg/dns"
 	log "github.com/sirupsen/logrus"
 
@@ -42,16 +47,55 @@ func SetupDNS(clientConfig *miekgdns.ClientConfig, _ []string) error {
 	}...)
 	output, err := cmd.CombinedOutput()
 	if err != nil {
-		log.Warnf("cmd: %s, output: %s, error: %v\n", cmd.Args, string(output), err)
+		log.Debugf("failed to exec cmd: %s, message: %s, ignore", strings.Join(cmd.Args, " "), string(output))
 	}
 
-	return nil
+	filename := filepath.Join("/", "etc", "resolv.conf")
+	readFile, err := os.ReadFile(filename)
+	if err == nil {
+		resolvConf, err := miekgdns.ClientConfigFromReader(bytes.NewBufferString(string(readFile)))
+		if err == nil {
+			if len(resolvConf.Servers) != 0 {
+				clientConfig.Servers = append(clientConfig.Servers, resolvConf.Servers...)
+			}
+			if len(resolvConf.Search) != 0 {
+				clientConfig.Search = append(clientConfig.Search, resolvConf.Search...)
+			}
+		}
+	}
+
+	return WriteResolvConf(*clientConfig)
 }
 
 func CancelDNS() {
 	updateHosts("")
+
+	filename := filepath.Join("/", "etc", "resolv.conf")
+	_ = os.Rename(getBackupFilename(filename), filename)
 }
 
 func GetHostFile() string {
 	return "/etc/hosts"
 }
+
+func WriteResolvConf(config miekgdns.ClientConfig) error {
+	var options []string
+	if config.Ndots != 0 {
+		options = append(options, fmt.Sprintf("ndots:%d", config.Ndots))
+	}
+	if config.Attempts != 0 {
+		options = append(options, fmt.Sprintf("attempts:%d", config.Attempts))
+	}
+	if config.Timeout != 0 {
+		options = append(options, fmt.Sprintf("timeout:%d", config.Timeout))
+	}
+
+	filename := filepath.Join("/", "etc", "resolv.conf")
+	_ = os.Rename(filename, getBackupFilename(filename))
+	_, err := resolvconf.Build(filename, config.Servers, config.Search, options)
+	return err
+}
+
+func getBackupFilename(filename string) string {
+	return filename + ".kubevpn_backup"
+}

pkg/dns/dns_server_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/docker/docker/libnetwork/resolvconf"
 	miekgdns "github.com/miekg/dns"
 	log "github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
@@ -178,3 +179,17 @@ func TestFix(t *testing.T) {
 		println(s)
 	}
 }
+
+func TestName(t *testing.T) {
+	temp, _ := os.CreateTemp("", "")
+	temp.Close()
+	println(temp.Name())
+	_, err := resolvconf.Build(temp.Name(), []string{"10.233.0.3", "10.233.97.159", "10.233.122.162"}, []string{
+		"vke-system.svc.cluster.local",
+		"svc.cluster.local",
+		"cluster.local",
+	}, []string{"ndots:5", "timeout:5"})
+	if err != nil {
+		panic(err)
+	}
+}