How to make a CoreOS's ISO file from pxe boot image

1. SYNOPSIS

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This documentation is written about how to make a CoreOS's ISO file from pxe boot image.

2. REQUIREMENTS

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This method is required to mkisofs So, you need an environment that can execute mkisofs. (e.g. on Linux)

3. HOW TO MAKE ISO

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3.1 Copy files

# Make working directory
$ mkdir ~/tmp && cd ~/tmp
$ mkdir -p coreos/{isolinux,syslinux,coreos}

# Download pxe boot files from CoreOS Repository (dev-channel)
$ cd coreos/coreos
$ curl -O http://storage.core-os.net/coreos/amd64-generic/dev-channel/coreos_production_pxe.vmlinuz
$ mv coreos_production_pxe.vmlinuz vmlinuz
$ curl -O http://storage.core-os.net/coreos/amd64-generic/dev-channel/coreos_production_pxe_image.cpio.gz
$ mv coreos_production_pxe_image.cpio.gz cpio.gz
$ cd ~/tmp/coreos/coreos && ls
cpio.gz  vmlinuz

# Download syslinux binaries
$ cd ~/tmp
$ curl -O https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.02.tar.gz
$ tar zxvf syslinux-6.02.tar.gz

# Copy syslinux binaries to work directory
$ cd ~/tmp
$ cp syslinux-6.02/bios/com32/chain/chain.c32 coreos/syslinux/
$ cp syslinux-6.02/bios/com32/lib/libcom32.c32 coreos/syslinux/
$ cp syslinux-6.02/bios/com32/libutil/libutil.c32 coreos/syslinux/
$ cp syslinux-6.02/bios/memdisk/memdisk coreos/syslinux/
$ ls coreos/syslinux
chain.c32  libcom32.c32  libutil.c32  memdisk

$ cp syslinux-6.02/bios/core/isolinux.bin coreos/isolinux/
$ cp syslinux-6.02/bios/com32/elflink/ldlinux/ldlinux.c32 coreos/isolinux/
$ ls coreos/isolinux
isolinux.bin  ldlinux.c32

3.2 Write configuration file

INCLUDE /syslinux/syslinux.cfg

prompt 0
default coreos

LABEL coreos
KERNEL /coreos/vmlinuz
APPEND initrd=/coreos/cpio.gz root=squashfs: state=tmpfs: sshkey="{YOUR SSH PUBLIC KEY} coreos pxe demo"

3.3 Make ISO File !

$ cd ~/tmp/coreos/
$ mkisofs -v -l -r -J -o ../coreos.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table .

3.4 Finished the all

Yay !

4. Author and Copyright

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• Author: Naoki OKAMURA (Nyarla)
  • Email: nyarla[ at ]thotep.net
  • Twitter: @nyarla
  • Github: @nyarla
• Unlicense:
  • This documentation is under the public domain.