90 lines
3 KiB
Nix
90 lines
3 KiB
Nix
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{ config, lib, modulesPath, pkgs, ... }:
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{
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imports = [
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(modulesPath + "/installer/netboot/netboot-minimal.nix")
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];
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# We are stateless, so just default to latest.
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system.stateVersion = config.system.nixos.version;
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# This is a variant of the upstream kexecScript that also allows embedding
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# a ssh key.
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system.build.kexecBoot = lib.mkForce (pkgs.writeScript "kexec-boot" ''
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#!/usr/bin/env bash
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set -ex
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shopt -s nullglob
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SCRIPT_DIR=$( cd -- "$( dirname -- "''${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
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INITRD_TMP=$(mktemp -d)
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cd "$INITRD_TMP"
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pwd
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mkdir initrd initrd/ssh
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pushd initrd
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if [ -e /root/.ssh/authorized_keys ]; then
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cat /root/.ssh/authorized_keys >> ssh/authorized_keys
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fi
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if [ -e /etc/ssh/authorized_keys.d/root ]; then
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cat /etc/ssh/authorized_keys.d/root >> ssh/authorized_keys
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fi
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for p in /etc/ssh/ssh_host_*; do
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cp -a "$p" ssh
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done
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find -type f | cpio -o -H newc | gzip -9 > ../extra.gz
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popd
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cat "''${SCRIPT_DIR}/initrd.gz" extra.gz > final.gz
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"$SCRIPT_DIR/kexec" --load "''${SCRIPT_DIR}/bzImage" \
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--initrd=final.gz \
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--command-line "init=${config.system.build.toplevel}/init ${toString config.boot.kernelParams}"
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# kexec will map the new kernel in memory so we can remove the kernel at this point
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rm -r "$INITRD_TMP"
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# Disconnect our background kexec from the terminal
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if [[ -e /dev/kmsg ]]; then
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# this makes logging visible in `dmesg`, or the system consol or tools like journald
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exec > /dev/kmsg 2>&1
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else
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exec > /dev/null 2>&1
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fi
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# We will kexec in background so we can cleanly finish the script before the hosts go down.
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# This makes integration with tools like terraform easier.
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nohup bash -c "sleep 6 && '$SCRIPT_DIR/kexec' -e" &
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'');
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system.build.kexecTarball = pkgs.callPackage (pkgs.path + "/nixos/lib/make-system-tarball.nix") {
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fileName = "nixos-kexec-installer-${pkgs.stdenv.hostPlatform.system}";
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contents = [
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{
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target = "/initrd.gz";
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source = "${config.system.build.netbootRamdisk}/initrd";
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}
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{
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target = "/bzImage";
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source = "${config.system.build.kernel}/${config.system.boot.loader.kernelFile}";
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}
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{
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target = "/kexec-boot";
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source = config.system.build.kexecBoot;
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}
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{
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target = "/kexec";
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source = "${pkgs.pkgsStatic.kexec-tools}/bin/kexec";
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}
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];
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};
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documentation.enable = false;
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# Not really needed. Saves a few bytes and the only service we are running is sshd, which we want to be reachable.
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networking.firewall.enable = false;
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# Restore ssh host and user keys if they are available.
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# This avoids warnings of unknown ssh keys.
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boot.initrd.postMountCommands = ''
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mkdir -p /mnt-root/etc/ssh /mnt-root/root/.ssh
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if [[ -f /ssh/authorized_keys ]]; then
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cp ssh/authorized_keys /mnt-root/root/.ssh/
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fi
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cp ssh/ssh_host_* /mnt-root/etc/ssh
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'';
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}
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