feat: add --dns and --dns-search flags to customize the vm dns configuration

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

README.md

@@ -169,6 +169,8 @@ Flags:
       --boot-fs string             Filesystem to use for the boot partition, ext4 or fat32
       --boot-size uint             Size of the boot partition in MB (default 100)
       --bootloader string          Bootloader to use: syslinux, grub, grub-bios, grub-efi, defaults to syslinux on amd64 and grub-efi on arm64
+      --dns strings                DNS servers to set in the generated image
+      --dns-search strings         DNS search domains to set in the generated image
       --force                      Override output qcow2 image
   -h, --help                       help for convert
       --hostname string            Hostname to set in the generated image (default "localhost")
@@ -328,6 +330,8 @@ Flags:
       --boot-fs string             Filesystem to use for the boot partition, ext4 or fat32
       --boot-size uint             Size of the boot partition in MB (default 100)
       --bootloader string          Bootloader to use: syslinux, grub, grub-bios, grub-efi, defaults to syslinux on amd64 and grub-efi on arm64
+      --dns strings                DNS servers to set in the generated image
+      --dns-search strings         DNS search domains to set in the generated image
       --build-arg stringArray      Set build-time variables
   -f, --file string                Name of the Dockerfile
       --force                      Override output qcow2 image

builder.go

@@ -84,10 +84,12 @@ type builder struct {
 	cmdLineExtra string
 	arch         string
 
-	hostname string
+	hostname  string
+	dns       []string
+	dnsSearch []string
 }
 
-func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64, osRelease OSRelease, format string, cmdLineExtra string, splitBoot bool, bootFS BootFS, bootSize uint64, luksPassword string, bootLoader string, platform, hostname string) (Builder, error) {
+func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64, osRelease OSRelease, format string, cmdLineExtra string, splitBoot bool, bootFS BootFS, bootSize uint64, luksPassword string, bootLoader string, platform, hostname string, dns, dnsSearch []string) (Builder, error) {
 	var arch string
 	switch platform {
 	case "linux/amd64":
@@ -184,6 +186,9 @@ func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64,
 	if hostname == "" {
 		hostname = "localhost"
 	}
+	if len(dns) == 0 {
+		dns = []string{"8.8.8.8"}
+	}
 	b := &builder{
 		osRelease:    osRelease,
 		config:       config,
@@ -201,6 +206,8 @@ func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64,
 		luksPassword: luksPassword,
 		arch:         arch,
 		hostname:     hostname,
+		dns:          dns,
+		dnsSearch:    dnsSearch,
 	}
 	if err := b.checkDependencies(); err != nil {
 		return nil, err
@@ -415,7 +422,7 @@ func (b *builder) setupRootFS(ctx context.Context) (err error) {
 	if err := b.chWriteFile("/etc/fstab", fstab, perm); err != nil {
 		return err
 	}
-	if err := b.chWriteFileIfNotExist("/etc/resolv.conf", "nameserver 8.8.8.8", 0644); err != nil {
+	if err := b.chWriteFile("/etc/resolv.conf", b.resolvConf(), 0644); err != nil {
 		return err
 	}
 	if err := b.chWriteFile("/etc/hostname", b.hostname+"\n", perm); err != nil {
@@ -500,6 +507,21 @@ func (b *builder) isLuksEnabled() bool {
 	return b.luksPassword != ""
 }
 
+func (b *builder) resolvConf() string {
+	var sb strings.Builder
+	for _, v := range b.dns {
+		sb.WriteString("nameserver ")
+		sb.WriteString(v)
+		sb.WriteString("\n")
+	}
+	if len(b.dnsSearch) > 0 {
+		sb.WriteString("search ")
+		sb.WriteString(strings.Join(b.dnsSearch, " "))
+		sb.WriteString("\n")
+	}
+	return sb.String()
+}
+
 func (b *builder) Close() error {
 	return b.img.Close()
 }

cmd/d2vm/build.go

@@ -111,6 +111,8 @@ var (
 				d2vm.WithPlatform(platform),
 				d2vm.WithPull(false),
 				d2vm.WithHostname(hostname),
+				d2vm.WithDNS(dns),
+				d2vm.WithDNSSearch(dnsSearch),
 			); err != nil {
 				return err
 			}

cmd/d2vm/convert.go

@@ -92,6 +92,8 @@ var (
 				d2vm.WithPlatform(platform),
 				d2vm.WithPull(pull),
 				d2vm.WithHostname(hostname),
+				d2vm.WithDNS(dns),
+				d2vm.WithDNSSearch(dnsSearch),
 			); err != nil {
 				return err
 			}

cmd/d2vm/flags.go

@@ -45,7 +45,9 @@ var (
 	keepCache bool
 	platform  string
 
-	hostname string
+	hostname  string
+	dns       []string
+	dnsSearch []string
 )
 
 func validateFlags() error {
@@ -119,5 +121,7 @@ func buildFlags() *pflag.FlagSet {
 	flags.StringVar(&platform, "platform", d2vm.Arch, "Platform to use for the container disk image, linux/arm64 and linux/arm64 are supported")
 	flags.BoolVar(&pull, "pull", false, "Always pull docker image")
 	flags.StringVar(&hostname, "hostname", "localhost", "Hostname to set in the generated image")
+	flags.StringSliceVar(&dns, "dns", []string{}, "DNS servers to set in the generated image")
+	flags.StringSliceVar(&dnsSearch, "dns-search", []string{}, "DNS search domains to set in the generated image")
 	return flags
 }

convert.go

@@ -88,7 +88,7 @@ func Convert(ctx context.Context, img string, opts ...ConvertOption) error {
 	if format == "" {
 		format = "raw"
 	}
-	b, err := NewBuilder(ctx, tmpPath, imgUUID, "", o.size, r, format, o.cmdLineExtra, o.splitBoot, o.bootFS, o.bootSize, o.luksPassword, o.bootLoader, o.platform, o.hostname)
+	b, err := NewBuilder(ctx, tmpPath, imgUUID, "", o.size, r, format, o.cmdLineExtra, o.splitBoot, o.bootFS, o.bootSize, o.luksPassword, o.bootLoader, o.platform, o.hostname, o.dns, o.dnsSearch)
 	if err != nil {
 		return err
 	}

convert_options.go

@@ -35,7 +35,9 @@ type convertOptions struct {
 	platform  string
 	pull      bool
 
-	hostname string
+	hostname  string
+	dns       []string
+	dnsSearch []string
 }
 
 func (o *convertOptions) hasGrubBIOS() bool {
@@ -135,3 +137,15 @@ func WithHostname(hostname string) ConvertOption {
 		o.hostname = hostname
 	}
 }
+
+func WithDNS(dns []string) ConvertOption {
+	return func(o *convertOptions) {
+		o.dns = dns
+	}
+}
+
+func WithDNSSearch(dnsSearch []string) ConvertOption {
+	return func(o *convertOptions) {
+		o.dnsSearch = dnsSearch
+	}
+}

docs/content/reference/d2vm_build.md

@@ -14,6 +14,8 @@ d2vm build [context directory] [flags]
       --boot-size uint             Size of the boot partition in MB (default 100)
       --bootloader string          Bootloader to use: syslinux, grub, grub-bios, grub-efi, defaults to syslinux on amd64 and grub-efi on arm64
       --build-arg stringArray      Set build-time variables
+      --dns strings                DNS servers to set in the generated image
+      --dns-search strings         DNS search domains to set in the generated image
   -f, --file string                Name of the Dockerfile
       --force                      Override output qcow2 image
   -h, --help                       help for build

docs/content/reference/d2vm_convert.md

@@ -13,6 +13,8 @@ d2vm convert [docker image] [flags]
       --boot-fs string             Filesystem to use for the boot partition, ext4 or fat32
       --boot-size uint             Size of the boot partition in MB (default 100)
       --bootloader string          Bootloader to use: syslinux, grub, grub-bios, grub-efi, defaults to syslinux on amd64 and grub-efi on arm64
+      --dns strings                DNS servers to set in the generated image
+      --dns-search strings         DNS search domains to set in the generated image
       --force                      Override output qcow2 image
   -h, --help                       help for convert
       --hostname string            Hostname to set in the generated image (default "localhost")