nixos/mods/pxeboot.nix

{ config, lib, pkgs, ... }:
{
  virtualisation.oci-containers.containers.fedora-dracut = {
    pull = "newer";
    autoStart = false;
    entrypoint = "bash";
    image = "docker.io/fedora:latest";
    cmd = [ "/data/workdir/entry.sh" ];
    volumes = [
      "/srv/nfs/arch/lower:/data/arch:ro"
      "/var/lib/podman-dracut:/data/workdir"
      "/srv/nfs/fedora/lower:/data/fedora:ro"
    ];
  };
  services = {
    nfs.server = {
      enable = true;
      exports = let
        clients."10.2.0.0/16" = [ "mp" "rw" "no_root_squash" ];
      in {
        "/srv/nfs/arch/root" = clients;
        "/srv/nfs/fedora/root" = clients;
      };
    };
    dnsmasq = {
      enable = true;
      settings = {
        enable-ra = true;
        no-resolv = true;
        cache-size = 4096;
        bogus-priv = true;
        enable-tftp = true;
        interface = "enp1s0";
        domain-needed = true;
        tftp-root = "/srv/tftp";
        dhcp-boot = "grubx64.efi";
        server = [ "1.1.1.2" "2606:4700:4700::1112"
        "1.0.0.2" "2606:4700:4700::1002" ];
        dhcp-range = [ "10.2.0.2,10.2.255.254,12h"
        "fc02::2,fc02::ffff:ffff:ffff:ffff,12h" ];
      };
    };
  };
  systemd = {
    tmpfiles.rules = [ "d /srv/tftp" ];
    services.pxeboot = {
      before = [ "nfs-server.service" ];
      requiredBy = [ "nfs-server.service" ];
      path = with pkgs; [ xz curl e2fsprogs grub2_efi util-linux ];
      serviceConfig = {
        Type = "oneshot";
        RemainAfterExit = true;
        ExecStop = pkgs.writeShellScript "stop.sh" ''
          set -e
          for distro in arch fedora; do
            cd /srv/nfs/$distro
            mountpoint -q root && umount root
            mountpoint -q lower && umount lower
            mountpoint -q loop && umount loop
          done
        '';
      };
      script = let
        resolv = pkgs.writeText "resolv.conf" ''
          nameserver fc02::1
          nameserver 10.2.0.1
          options edns0 trust-ad
        '';
        archIso = {
          rootfs = "arch/x86_64/airootfs.sfs";
          hash = "684ded26c63240ff4a41e8c25ee84ea6da233f557364821f13d12c2b0a9059a5";
          url = "https://fastly.mirror.pkgbuild.com/iso/2026.10.01/archlinux-x86_64.iso";
        };
        fedoraIso = {
          rootfs = "LiveOS/squashfs.img";
          hash = "1620295f6a00c27c3208f0c00b8ece4eab1ec69b9002152d97488bf26a426ddf";
          url = "https://download.fedoraproject.org/pub/fedora/linux/releases/" +
          "44/Workstation/x86_64/iso/Fedora-Workstation-Live-44-1.7.x86_64.iso";
        };
        grubCfg = pkgs.writeText "grub.cfg" ''
          function load {
            set p=$cmdpath/boot/$1
            linux $p/vmlinuz $2 rw ip=dhcp root=nfs4:$net_default_server:/srv/nfs/$1/root
            initrd $p/boot/$1/initramfs
          }
          menuentry Arch {
            load arch
          }
          menuentry Fedora {
            load fedora selinux=0
          }
        '';
        entryScript = pkgs.writeShellScript "entry.sh" ''
          set -e
          dnf install -y nfs-utils dracut-network
          cd /data/workdir
          for target in $(ls .. | grep -v workdir); do
            mkdir $target
            modsDir=../$target/usr/lib/modules/*
            cp $modsDir/vmlinuz $target
            dracut -Nm "network-manager nfs" --zstd -k $modsDir \
              --kver $(basename $modsDir) $target/initramfs
          done
        '';
      in ''
        for distro in arch fedora; do
          case $distro in
            arch) url=${archIso.url}
            rootfs=${archIso.rootfs}
            hash=${archIso.hash};;
            fedora) url=${fedoraIso.url}
            rootfs=${fedoraIso.rootfs}
            hash=${fedoraIso.hash};;
          esac
          mkdir -p /srv/nfs/$distro
          cd /srv/nfs/$distro
          if [ ! -e $distro.iso ]; then
            curl -C - "$url" -Lo $distro.iso.tmp
            mv $distro.iso{.tmp,}
            sha256sum $distro.iso | grep $hash
          fi
          mkdir -p loop root work lower upper
          mountpoint -q loop || mount $distro.iso loop
          mountpoint -q lower || mount loop/$rootfs lower
          mountpoint -q root || mount -t overlay overlay root -o \
            workdir=work,nfs_export=on,lowerdir=lower,upperdir=upper
          if [ ! -e upper/etc/resolv.conf ]; then
            cd root/etc
            rm -f resolv.conf
            cp ${resolv} resolv.conf
            chattr +i resolv.conf
          fi
        done
        cd /srv/tftp
        if [ ! -e grubx64.efi ]; then
          grub-mkstandalone -O x86_64-efi --compress=xz -o \
            grubx64.efi --modules=efinet /boot/grub/grub.cfg=${grubCfg}
        fi
        if [ ! -e boot ]; then
          workdir=/var/lib/podman-dracut
          rm -rf $workdir
          mkdir boot $workdir
          cp ${entryScript} $workdir/entry.sh
          systemctl --wait start podman-fedora-dracut.service
          mv $workdir/*/ boot
          chmod -R 644 boot
          chmod +x $(find boot -type d)
        fi
      '';
    };
  };
}