Simple Python Script to Edit an Ubuntu ISO to Add Automated Server Install Capability

edit_ubuntu_autoinstall.py

import io
import pathlib

import pycdlib

ubuntu = pathlib.Path('ubuntu-22.04.1-live-server-amd64.iso')
new_iso_path = pathlib.Path('ubuntu-22.04.1-live-server-amd64-auto.iso')

iso = pycdlib.PyCdlib()
iso.open(ubuntu)

extracted = io.BytesIO()
iso.get_file_from_iso_fp(extracted, iso_path='/BOOT/GRUB/GRUB.CFG;1')
extracted.seek(0)
data = extracted.read()
print(data.decode())

new = data.replace(b' ---', b'quiet autoinstall ds=nocloud\;s=/cdrom/nocloud/ ---')
print(new.decode())

iso.rm_file(iso_path='/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')
iso.add_fp(io.BytesIO(new), len(new), '/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')

iso.add_directory('/NOCLOUD', rr_name='nocloud')

user_data = b"""#cloud-config
autoinstall:
  version: 1
  identity:
    hostname: ubuntu-server
    password: "$6$exDY1mhS4KUYCE/2$zmn9ToZwTKLhCw.b4/b.ZRTIZM30JZ4QrOQ2aOXJ8yk96xpcCof0kxKwuX1kqLG/ygbJ1f8wxED22bTL4F46P0"
    username: ubuntu
"""

iso.add_fp(io.BytesIO(user_data), len(user_data), '/NOCLOUD/USER_DATA;1', rr_name='user-data')
iso.add_fp(io.BytesIO(b''), len(b''), '/NOCLOUD/META_DATA;1', rr_name='meta-data')
iso.write(new_iso_path)
iso.close()

edit_ubuntu_autoinstall_simple.py

import io
import pathlib

import pycdlib

ubuntu = pathlib.Path('ubuntu-22.04.1-live-server-amd64.iso')
new_iso = pathlib.Path('ubuntu-22.04.1-live-server-amd64-auto.iso')

iso = pycdlib.PyCdlib()
iso.open(ubuntu)

extracted = io.BytesIO()
iso.get_file_from_iso_fp(extracted, iso_path='/BOOT/GRUB/GRUB.CFG;1')
extracted.seek(0)
data = extracted.read()
print(data.decode())

new = data.replace(b' ---', b'quiet autoinstall ---').replace(b'timeout=30', b'timeout=1')
print(new.decode())

iso.rm_file(iso_path='/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')
iso.add_fp(io.BytesIO(new), len(new), '/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')

iso.write(new_iso)
iso.close()

make_cloud_init_data_iso.py

import io
import pathlib

import pycdlib

new_iso = pathlib.Path('ubuntu-22.04-auto.iso')

iso = pycdlib.PyCdlib()
iso.new(rock_ridge='1.09', vol_ident='CIDATA')

user_data = b"""#cloud-config
autoinstall:
  version: 1
  identity:
    hostname: ubuntu-server
    password: "$6$exDY1mhS4KUYCE/2$zmn9ToZwTKLhCw.b4/b.ZRTIZM30JZ4QrOQ2aOXJ8yk96xpcCof0kxKwuX1kqLG/ygbJ1f8wxED22bTL4F46P0"
    username: ubuntu
"""

iso.add_fp(io.BytesIO(user_data), len(user_data), '/USERDATA;1', rr_name='user-data')
iso.add_fp(io.BytesIO(b''), len(b''), '/METADATA;1', rr_name='meta-data')

iso.write(new_iso)
iso.close()

For changing the grub menu, just do a complete replacement of it, you can delete menu points, and edit timeout parameters if needed.
Example untested:

import io
import pathlib

import pycdlib

ubuntu = pathlib.Path('ubuntu-22.04.1-live-server-amd64.iso')
new_iso = pathlib.Path('ubuntu-22.04.1-live-server-amd64-auto.iso')

iso = pycdlib.PyCdlib()
iso.open(ubuntu)

extracted = io.BytesIO()
iso.get_file_from_iso_fp(extracted, iso_path='/BOOT/GRUB/GRUB.CFG;1')
extracted.seek(0)
data = """YOUR GRUB CFG FILE HERE
"""

iso.rm_file(iso_path='/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')
iso.add_fp(io.BytesIO(data), len(data), '/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')

iso.write(new_iso)
iso.close()

Great work, any chance you can add in the md5 process to remove the verification issue from the edit of grub and to just plain remove the enforced check?

Clear out the md5sum.txt file to cancel install verification of files.

iso.rm_file(iso_path='/md5sum.txt;1', rr_name='md5sum.txt')
iso.add_fp(io.BytesIO("", len(""), '/md5sum.txt;1', rr_name='md5sum.txt')

You could edit the md5 sum of grub in that file if you felt like it for real verification..

Thanks, I personally don't require a verification check. I just happened to notice during the process it was failing validation from the change to the grub.cfg. Thanks for posting the additional content to disable the check and thanks for your work! Made my life easier that's for sure :)

Made some modifications to disable the verifications for future reference.

import io
import pathlib

import pycdlib

ubuntu = pathlib.Path('ubuntu-20.04.5-live-server-amd64.iso')
new_iso = pathlib.Path('ubuntu-20.04.5-live-server-amd64-auto.iso')

iso = pycdlib.PyCdlib()
iso.open(ubuntu)

extracted = io.BytesIO()
iso.get_file_from_iso_fp(extracted, iso_path='/BOOT/GRUB/GRUB.CFG;1')
extracted.seek(0)
data = extracted.read()
print(data.decode())

new = data.replace(b'Install Ubuntu Server', b'Autoinstall Ubuntu Server - Disabled Verfification').replace(b' ---', b'quiet autoinstall fsck.mode=skip ---').replace(b'timeout=30', b'timeout=1')
print(new.decode())

iso.rm_file(iso_path='/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')
iso.add_fp(io.BytesIO(new), len(new), '/BOOT/GRUB/GRUB.CFG;1', rr_name='grub.cfg')

iso.write(new_iso)
iso.close()