Allow adding hosts, setting hostname, nameservers and search domains

README.md

@@ -166,11 +166,15 @@ Usage:
 
 Flags:
       --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
+      --add-host strings           Add a custom host-to-IP mapping (host:ip) to the /etc/hosts file in the generated image
       --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")
       --keep-cache                 Keep the images after the build
       --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
       --network-manager string     Network manager to use for the image: none, netplan, ifupdown
@@ -324,13 +328,17 @@ Usage:
 
 Flags:
       --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
+      --add-host strings           Add a custom host-to-IP mapping (host:ip) to the /etc/hosts file in the generated image
       --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
   -h, --help                       help for build
+      --hostname string            Hostname to set in the generated image (default "localhost")
       --keep-cache                 Keep the images after the build
       --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
       --network-manager string     Network manager to use for the image: none, netplan, ifupdown

builder.go

@@ -83,9 +83,14 @@ type builder struct {
 
 	cmdLineExtra string
 	arch         string
+
+	hostname  string
+	dns       []string
+	dnsSearch []string
+	hosts     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 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, extraHosts map[string]string) (Builder, error) {
 	var arch string
 	switch platform {
 	case "linux/amd64":
@@ -179,6 +184,16 @@ func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64,
 	// 	logrus.Warnf("%s is smaller than rootfs size, using %s", datasize.ByteSize(size), s)
 	// 	size = int64(s)
 	// }
+	if hostname == "" {
+		hostname = "localhost"
+	}
+	if len(dns) == 0 {
+		dns = []string{"8.8.8.8"}
+	}
+	hosts := hosts
+	for k, v := range extraHosts {
+		hosts += fmt.Sprintf("%s %s\n", v, k)
+	}
 	b := &builder{
 		osRelease:    osRelease,
 		config:       config,
@@ -195,6 +210,10 @@ func NewBuilder(ctx context.Context, workdir, imgTag, disk string, size uint64,
 		bootFS:       bootFS,
 		luksPassword: luksPassword,
 		arch:         arch,
+		hostname:     hostname,
+		dns:          dns,
+		dnsSearch:    dnsSearch,
+		hosts:        hosts,
 	}
 	if err := b.checkDependencies(); err != nil {
 		return nil, err
@@ -409,13 +428,13 @@ 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.chWriteFileIfNotExist("/etc/hostname", "localhost", perm); err != nil {
+	if err := b.chWriteFile("/etc/hostname", b.hostname+"\n", perm); err != nil {
 		return err
 	}
-	if err := b.chWriteFileIfNotExist("/etc/hosts", hosts, perm); err != nil {
+	if err := b.chWriteFile("/etc/hosts", b.hosts, perm); err != nil {
 		return err
 	}
 	// TODO(adphi): is it the righ fix ?
@@ -494,6 +513,21 @@ 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

@@ -110,6 +110,10 @@ var (
 				d2vm.WithKeepCache(keepCache),
 				d2vm.WithPlatform(platform),
 				d2vm.WithPull(false),
+				d2vm.WithHostname(hostname),
+				d2vm.WithDNS(dns),
+				d2vm.WithDNSSearch(dnsSearch),
+				d2vm.WithExtraHosts(extraHosts),
 			); err != nil {
 				return err
 			}

cmd/d2vm/convert.go

@@ -91,6 +91,10 @@ var (
 				d2vm.WithKeepCache(keepCache),
 				d2vm.WithPlatform(platform),
 				d2vm.WithPull(pull),
+				d2vm.WithHostname(hostname),
+				d2vm.WithDNS(dns),
+				d2vm.WithDNSSearch(dnsSearch),
+				d2vm.WithExtraHosts(extraHosts),
 			); err != nil {
 				return err
 			}

cmd/d2vm/flags.go

@@ -44,9 +44,16 @@ var (
 
 	keepCache bool
 	platform  string
+
+	hostname  string
+	dns       []string
+	dnsSearch []string
+	hosts     []string
+
+	extraHosts map[string]string
 )
 
-func validateFlags() error {
+func validateFlags() (err error) {
 	switch platform {
 	case "linux/amd64":
 		if bootloader == "" {
@@ -94,6 +101,10 @@ func validateFlags() error {
 			return fmt.Errorf("%s already exists", output)
 		}
 	}
+	extraHosts, err = validateHosts(hosts...)
+	if err != nil {
+		return fmt.Errorf("invalid --add-host value: %w", err)
+	}
 	return nil
 }
 
@@ -116,5 +127,22 @@ func buildFlags() *pflag.FlagSet {
 	flags.BoolVar(&keepCache, "keep-cache", false, "Keep the images after the build")
 	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")
+	flags.StringSliceVar(&hosts, "add-host", []string{}, "Add a custom host-to-IP mapping (host:ip) to the /etc/hosts file in the generated image")
 	return flags
 }
+
+func validateHosts(vals ...string) (map[string]string, error) {
+	out := make(map[string]string)
+	for _, val := range vals {
+		// allow for IPv6 addresses in extra hosts by only splitting on first ":"
+		k, v, ok := strings.Cut(val, ":")
+		if !ok || k == "" {
+			return nil, fmt.Errorf("bad format for add-host: %q", val)
+		}
+		out[k] = v
+	}
+	return out, nil
+}

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)
+	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, o.hosts)
 	if err != nil {
 		return err
 	}

convert_options.go

@@ -34,6 +34,11 @@ type convertOptions struct {
 	keepCache bool
 	platform  string
 	pull      bool
+
+	hostname  string
+	dns       []string
+	dnsSearch []string
+	hosts     map[string]string
 }
 
 func (o *convertOptions) hasGrubBIOS() bool {
@@ -127,3 +132,27 @@ func WithPull(b bool) ConvertOption {
 		o.pull = b
 	}
 }
+
+func WithHostname(hostname string) ConvertOption {
+	return func(o *convertOptions) {
+		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
+	}
+}
+
+func WithExtraHosts(hosts map[string]string) ConvertOption {
+	return func(o *convertOptions) {
+		o.hosts = hosts
+	}
+}

docs/content/reference/d2vm_build.md

@@ -9,14 +9,18 @@ d2vm build [context directory] [flags]
 ### Options
 
 ```
+      --add-host strings           Add a custom host-to-IP mapping (host:ip) to the /etc/hosts file in the generated image
       --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
       --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
       --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
+      --hostname string            Hostname to set in the generated image (default "localhost")
       --keep-cache                 Keep the images after the build
       --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
       --network-manager string     Network manager to use for the image: none, netplan, ifupdown

docs/content/reference/d2vm_convert.md

@@ -9,12 +9,16 @@ d2vm convert [docker image] [flags]
 ### Options
 
 ```
+      --add-host strings           Add a custom host-to-IP mapping (host:ip) to the /etc/hosts file in the generated image
       --append-to-cmdline string   Extra kernel cmdline arguments to append to the generated one
       --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")
       --keep-cache                 Keep the images after the build
       --luks-password string       Password to use for the LUKS encrypted root partition. If not set, the root partition will not be encrypted
       --network-manager string     Network manager to use for the image: none, netplan, ifupdown