netbootcd-ipxe-bootchain
A modified version of the amazing IsaacSchemm/netbootcd to be booted over iPXE, without internet, and bootchain a linux image distro over the network.
The main reason netbootcd-ipxe-bootchain exists is to bootstrap a linux environment as an intermediate (more advanced and flexible) boot environment than grub.
Within this environment we can do clever things, like for example:
* customize the actual boot process via a custom script that is downloadable from the network, either via tftp or http (by passing nb_provisionurl=<url> as kernel parameter)
* debug a faulty boot remotely, by logging in over ssh (something we can't do with grub).
* extract the kernel and ramdisk files from inside an actual boot disk image, and use kexec to boot from it.
* make a copy of the actual boot image file from the network storage to a local disk cache and boot from it, instead of using NBD, iSCSI or NFS to load the image directly from the network storage.
Associated with iPXE, netbootcd-ipxe-bootchain is a very useful and effective way to remotely administer bare metal computers boot process.
Build
Just run make and it should build it using docker.
After the build, you should find tinycore kernel and initrd inside ./boot/ folder.
In ./boot/ you will also find a messy init.sh example script that can be used by passing nb_provisionurl=<tftp/http url>/init.sh parameter to the kernel.
An example of a grub menu option, assuming we have a tftp server at 192.168.0.1, serving this git depot as tftp root:
menuentry 'netbootcd-ipxe-bootchain' --class os {
echo Reading kernel
linux boot/vmlinuz quiet nb_provisionurl=tftp://192.168.0.1/boot/http/init.sh nofstab waitusb norestore base console=tty0 console=ttyS0,115200n8
echo Reading ramdisk
initrd boot/nbinit4.gz
echo booting...
}