The iPXE script should define a static IP for Alpine Linux through the `ip` kernel parameter

[NoSpawnn]

Is your feature request related to a problem? Please describe.
Currently, Alpine Linux only successfully boots when ip=dhcp is defined in the iPXE boot script. This is not entirely acceptable, it needs to support static IP definitions.

Describe the solution you'd like
The ip kernel parameter must take and apply a static IP definition of the form described in the Alpine initramfs-init script defined here

Describe alternatives you've considered
We could continue to rely on DHCP, or perhaps offer it as an option if users would prefer to use that over static IPs.

Additional context
This has been a super annoying issue for a while, a qemu example using raw kernel/initramfs files is shown below, run from the root of this project directory after the alpine build script has run at least once.

#!/bin/sh

qemu_args=(
    -enable-kvm
    -cpu max
    -smp 4
    -m 4096
    -kernel ./deploy/serve/www/iso/alpine-netboot/boot/vmlinuz-lts
    -initrd ./deploy/serve/www/iso/alpine-netboot/boot/initramfs-lts
    -serial mon:stdio
    # Confirmed correct IP syntax example
    -append "console=ttyS0 init=/sbin/init ip=10.0.2.15::10.0.2.2:255.255.255.0::eth0:off:10.0.2.3:: alpine_repo=http://dl-cdn.alpinelinux.org/alpine/v3.20/main"
    -display none
    -device virtio-net-pci,netdev=mynet0
    -netdev user,id=mynet0
)

qemu-system-x86_64 "${qemu_args[@]}"

I will update this issue should a successful iPXE-based boot occur.

[NoSpawnn]

Below is a fully working qemu iPXE boot example (still relying on DHCP for chaining, but that can be easily changed, and should be)

• iPXE embedded script

#!ipxe

echo Setting temporary DHCP address to chain into bootfile
dhcp

set chain-url http://192.168.1.29:8080/bootfile
echo Chaining to ${chain_url}
chain ${chain-url}?uuid=${uuid}

• The chained bootfile, hosted on a web server on the local machine at the address specified above

#!ipxe

# The iPXE script below is based on:
# https://boot.alpinelinux.org/boot.ipxe
# https://wiki.alpinelinux.org/wiki/PXE_boot

# --- Network configuration (static IP) ---
set static-ip 10.0.2.15
set static-gw 10.0.2.2
set static-mask 255.255.255.0
set static-dns 10.0.2.3

# --- Alpine version info ---
set alpine-branch v3.20
set alpine-flavour lts
set arch x86_64

# --- iPXE boot sources ---
set web-server http://192.168.1.29:8080
set boot-base-url ${web-server}/iso/alpine-netboot/boot
set kernel-url ${boot-base-url}/vmlinuz-${alpine-flavour}
set modloop-url ${boot-base-url}/modloop-${alpine-flavour}
set initramfs-image initramfs-${alpine-flavour}
set initramfs-url ${boot-base-url}/${initramfs-image}
set sshkey-url ${web-server}/ssh/key.pub
set alpine-repo http://dl-cdn.alpinelinux.org/alpine/${alpine-branch}/main

# ---------------------------
# |    Boot script start    |
# ---------------------------

# --- Configure network for PXE ---
set pxe-iface net0
echo Configuring iface for PXE (${pxe-iface}: ip=${static-ip},mask=${static-mask},gw=${static-gw},dns=${static-dns})
ifopen ${pxe-iface}
set ${pxe-iface}/ip:ipv4 ${static-ip}
set ${pxe-iface}/netmask:ipv4 ${static-mask}
set ${pxe-iface}/gateway:ipv4 ${static-gw}
set ${pxe-iface}/dns:ipv4 ${static-dns}
ifstat

imgfree

initrd ${initramfs-url}
kernel ${kernel-url} netpoll.carrier_timeout=120 console=ttyS0 modules=loop,squashfs nomodeset ip=${static-ip}::${static-gw}:${static-mask}::${static-iface}:none:${static-dns} alpine_repo=${alpine-repo} modloop=${modloop-url} ssh_key=${sshkey-url}

boot

1. Build the iPXE ISO
2. Run the following, modified version of the earlier qemu script

#!/bin/sh

qemu_args=(
    -enable-kvm # utilize hardware virtualization of processors
    -cpu max  # Enables all features supported by the accelerator in the current host
    -smp 4
    -m 4096
    -display none
    -device virtio-net-pci,netdev=mynet0
    -netdev user,id=mynet0
    -cdrom ./deploy/serve/www/ipxe.iso
    -boot d
    -nographic
)

# Start qemu with the above args
qemu-system-x86_64 "${qemu_args[@]}"

[NoSpawnn]

The ordering of ifopen in the iPXE script appears irrelevant, so

ifopen ${pxe-iface}
set ${pxe-iface}/ip:ipv4 ${static-ip}
set ${pxe-iface}/netmask:ipv4 ${static-mask}
set ${pxe-iface}/gateway:ipv4 ${static-gw}
set ${pxe-iface}/dns:ipv4 ${static-dns}
ifstat

appears functionally equivalent to

set ${pxe-iface}/ip:ipv4 ${static-ip}
set ${pxe-iface}/netmask:ipv4 ${static-mask}
set ${pxe-iface}/gateway:ipv4 ${static-gw}
set ${pxe-iface}/dns:ipv4 ${static-dns}
ifopen ${pxe-iface}
ifstat

[NoSpawnn]

The ordering of initrd and kernel calls appears irrelevant, so

initrd ...
kernel ...

appears functionally equivalent to

kernel ...
initrd ...

[NoSpawnn]

The issue causing the error /sbin/init not found in new root. Launching emergency recovery shell is caused by something to do with passing the interface incorrectly and subsequently DNS being somehow set incorrectly?

in the init script, doing an nslookup to the given alpine_repo's root domain causes init to succeed

[NoSpawnn]

Modifying the init script by placing the following at the end of the configure_ip() function

local alpine_repo_domain=$(echo "$ALPINE_REPO" | sed -E 's#https?://([^/]+).*#\1#')
while ! ping -c 1 $alpine_repo_domain ; do
    sleep 1
done

or more correctly

if [ -n "$ALPINE_REPO" -a "$ALPINE_REPO" != "auto" ]; then
    ebegin "Awaiting accesible Alpine repo at $ALPINE_REPO"
   local alpine_repo_domain=$(echo "$ALPINE_REPO" | sed -E 's#https?://([^/]+).*#\1#')
   while ! ping -c 1 $alpine_repo_domain ; do
       sleep 1
    done
    eend $?
fi

essentially ensuring that the given alpine repo is reachable before continuing

TODO: the alpine_repo kernel parameter can take multiple comma separated repos. Need to support taht