Provided by: nobodd-tools_0.4-0ubuntu1_all 
NAME
nobodd-prep - nobodd-prep - prepare an OS image for NBD netboot
Customizes an OS image to prepare it for netbooting via TFTP. Specifically, this expands the image to a
specified size (the assumption being the image is a copy of a minimally sized template image), then
updates the kernel command line on the boot partition to point to an NBD server.
SYNOPSIS
usage: nobodd-prep [-h] [--version] [-s SIZE] [--nbd-host HOST]
[--nbd-name NAME] [--cmdline NAME]
[--boot-partition NUM] [--root-partition NUM]
[-C PATH] [-R PATH] image
OPTIONS
image The target image to customize
-h, --help
show the help message and exit
--version
show program's version number and exit
-s SIZE, --size SIZE
The size to expand the image to; default: 16GB
--nbd-host HOST
The hostname of the nbd server to connect to for the root device; defaults to the local machine's
FQDN
--nbd-name NAME
The name of the nbd share to use as the root device; defaults to the stem of the image name
--cmdline NAME
The name of the file containing the kernel command line on the boot partition; default:
cmdline.txt
--boot-partition NUM
Which partition is the boot partition within the image; default is the first FAT partition
(identified by partition type) found in the image
--root-partition NUM
Which partition is the root partition within the image default is the first non-FAT partition
(identified by partition type) found in the image
-C PATH, --copy PATH
Copy the specified file or directory into the boot partition. This may be given multiple times to
specify multiple items to copy
-R PATH, --remove PATH
Delete the specified file or directory within the boot partition. This may be given multiple times
to specify multiple items to delete
--serial HEX
Defines the serial number of the Raspberry Pi that will be served this image. When this option is
given, a board configuration compatible with nobodd-tftpd may be output with --tftpd-conf
--tftpd-conf FILE
If specified, write a board configuration compatible with nobodd-tftpd to the specified file;
requires --serial to be given. If "-" is given, output is written to stdout.
--nbd-conf FILE
If specified, write a share configuration compatible with nbd-server(1) to the specified file. If
"-" is given, output is written to stdout.
USAGE
Typically nobodd-prep is called with a base OS image. For example, if ubuntu-24.04-server.img.xz is the
Ubuntu 24.04 Server for Raspberry image, we would decompress it (we can only work on uncompressed
images), use the tool to expand it to a reasonable disk size (e.g. 16GB like an SD card), and customize
the kernel command line to look for the rootfs on our NBD server:
$ ls -l ubuntu-24.04-server.img.xz
-rw-rw-r-- 1 dave dave 1189280360 Oct 12 00:44 ubuntu-24.04-server.img.xz
$ unxz ubuntu-24.04-server.img.xz
$ ls -l ubuntu-24.04-server.img
-rw-rw-r-- 1 dave dave 3727687680 Oct 12 00:44 ubuntu-24.04-server.img
$ fdisk -l ubuntu-24.04-server.img
Disk ubuntu-24.04-server.img: 3.47 GiB, 3727687680 bytes, 7280640 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x1634ec00
Device Boot Start End Sectors Size Id Type
ubuntu-24.04-server.img1 * 2048 1050623 1048576 512M c W95 FAT32 (LBA)
ubuntu-24.04-server.img2 1050624 7247259 6196636 3G 83 Linux
$ mkdir mnt
$ sudo mount -o loop,offset=$((2048*512)),sizelimit=$((1048576*512)) ubuntu-24.04-server.img mnt/
[sudo] Password:
$ cat mnt/cmdline.txt
console=serial0,115200 multipath=off dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait fixrtc
$ sudo umount mnt/
$ nobodd-prep --size 16GB ubuntu-24.04-server.img
$ ls -l ubuntu-24.04-server.img --nbd-host myserver --nbd-name ubuntu
-rw-rw-r-- 1 dave dave 17179869184 Feb 27 13:11 ubuntu-24.04-server.img
$ sudo mount -o loop,offset=$((2048*512)),sizelimit=$((1048576*512)) ubuntu-24.04-server.img mnt/
[sudo] Password:
$ cat mnt/cmdline.txt
ip=dhcp nbdroot=myserver/ubuntu root=/dev/nbd0p2 console=serial0,115200 multipath=off dwc_otg.lpm_enable=0 console=tty1 rootfstype=ext4 rootwait fixrtc
$ sudo umount mnt/
Note, the only reason we are listing partitions and mounting the boot partition above is to demonstrate
the change to the kernel command line in cmdline.txt. Ordinarily, usage of nobodd-prep is as simple as:
$ unxz ubuntu-24.04-server.img.xz
$ nobodd-prep --size 16GB ubuntu-24.04-server.img
Typically nobodd-prep will detect the boot and root partitions of the image automatically. The boot
partition is defined as the first partition that has a FAT partition type
<https://en.wikipedia.org/wiki/Partition_type> (on MBR-partitioned
<https://en.wikipedia.org/wiki/Master_boot_record> images), or Basic Data
<https://en.wikipedia.org/wiki/Microsoft_basic_data_partition> or EFI System
<https://en.wikipedia.org/wiki/EFI_system_partition> partition type (on GPT-partitioned
<https://en.wikipedia.org/wiki/GUID_Partition_Table> images), which contains a valid FAT file-system (the
script tries to determine the FAT-type of the contained file-system, and only counts those partitions on
which it can determine a valid FAT-type).
The root partition is the exact opposite; it is defined as the first partition that doesn't have a FAT
partition type <https://en.wikipedia.org/wiki/Partition_type> (on MBR-partitioned
<https://en.wikipedia.org/wiki/Master_boot_record> images), or Basic Data
<https://en.wikipedia.org/wiki/Microsoft_basic_data_partition> or EFI System
<https://en.wikipedia.org/wiki/EFI_system_partition> partition type (on GPT-partitioned
<https://en.wikipedia.org/wiki/GUID_Partition_Table> images), which contains something other than a valid
FAT file-system (again, the script tries to determine the FAT-type of the contained file-system, and only
counts those partitions on which it cannot determine a valid FAT-type).
There may be images for which these simplistic definitions do not work. For example, images derived from
a NOOBS/PINN <https://github.com/procount/pinn> install may well have several boot partitions for
different installed OS'. In this case the boot or root partition (or both) may be specified manually on
the command line:
$ fdisk -l pinn-test.img
Disk pinn-test.img: 29.72 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x2e779525
Device Boot Start End Sectors Size Id Type
pinn-test.img1 8192 137215 129024 63M e W95 FAT16 (LBA)
pinn-test.img2 137216 62333951 62196736 29.7G 5 Extended
pinn-test.img5 139264 204797 65534 32M 83 Linux
pinn-test.img6 204800 464895 260096 127M c W95 FAT32 (LBA)
pinn-test.img7 466944 4661247 4194304 2G 83 Linux
pinn-test.img8 4669440 5193727 524288 256M 83 Linux
pinn-test.img9 5201920 34480125 29278206 14G 83 Linux
pinn-test.img10 34480128 34998271 518144 253M c W95 FAT32 (LBA)
pinn-test.img11 35004416 62333951 27329536 13G 83 Linux
$ nobodd-prep --boot-partition 10 --root-partition 11 pinn-test.img
nobodd-prep also includes several facilities for customizing the boot partition beyond re-writing the
kernel's cmdline.txt. Specifically, the --remove and --copy options.
The --remove option can be given multiple times, and tells nobodd-prep to remove the specified files or
directories from the boot partition. The --copy option can also be given multiple times, and tells
nobodd-prep to copy the specified files or directories into the root of the boot partition. In both
cases, directories that are specified are removed or copied recursively.
The --copy option is particularly useful for overwriting the cloud-init
<https://cloudinit.readthedocs.io/en/latest/> seeds on the boot partition of Ubuntu Server images, in
case you want to provide an initial network configuration, user setup, or list of packages to install on
first boot:
$ cat user-data
chpasswd:
expire: true
users:
- name: ubuntu
password: raspberry
type: text
ssh_pwauth: false
package_update: true
package_upgrade: true
packages:
- avahi-daemon
$ nobodd-prep --copy user-data ubuntu-24.04-server.img
There is no need to --remove files you wish to --copy; the latter option will overwrite where necessary.
The exception to this is copying directories; if you are copying a directory that already exists in the
boot partition, the new content will be merged with the existing content. Files under the directory that
share a name will be overwritten, files that do not will be left in place. If you wish to replace the
directory wholesale, specify it with --remove as well.
The ordering of options on the command line does not affect the order of operations in the utility. The
order of operations in nobodd-prep is strictly as follows:
1. Detect partitions, if necessary
2. Re-size the image, if necessary
3. Remove all items on the boot partition specified by --remove
4. Copy all items specified by --copy into the boot partition
5. Re-write the root= option in the cmdline.txt file
This ordering is deliberate, firstly to ensure directories can be replaced (as noted above), and secondly
to ensure cmdline.txt can be customized by --copy prior to the customization performed by the utility.
SEE ALSO
nobodd-tftpd(1), nbd-server(1)
BUGS
Please report bugs at: https://github.com/waveform80/nobodd/issues
AUTHOR
Dave Jones
COPYRIGHT
2023-2024 Dave Jones
0.4 Mar 01, 2024 NOBODD-PREP(1)