add kexec installer

This commit is contained in:
Jörg Thalheim 2022-09-04 14:57:14 +02:00
parent f094d7ed26
commit ae8e11cbfc
3 changed files with 175 additions and 0 deletions

View file

@ -26,11 +26,20 @@ build_kexec_bundle() {
echo "$tmp/kexec-bundle-$arch" echo "$tmp/kexec-bundle-$arch"
} }
build_kexec_installer() {
declare -r tag=$1 arch=$2 tmp=$3
# run the test once we have kvm support in github actions
# ignore=$(nix-build ./nix/kexec-installer-test.nix -I "nixpkgs=https://github.com/NixOS/nixpkgs/archive/${tag}.tar.gz" --argstr system "$arch")
out=$(nix-build '<nixpkgs/nixos>' -o "$tmp/kexec-installer-$arch" -I nixos-config=./nix/kexec-installer.nix -I "nixpkgs=https://github.com/NixOS/nixpkgs/archive/${tag}.tar.gz" --argstr system "$arch" -A config.system.build.kexecTarball)
echo "$out/tarball/nixos-kexec-installer-$arch.tar.xz"
}
main() { main() {
declare -r tag=${1:-nixos-unstable} arch=${2:-x86_64-linux} declare -r tag=${1:-nixos-unstable} arch=${2:-x86_64-linux}
tmp="$(mktemp -d)" tmp="$(mktemp -d)"
trap 'rm -rf -- "$tmp"' EXIT trap 'rm -rf -- "$tmp"' EXIT
readarray -t assets < <( readarray -t assets < <(
build_kexec_installer "$tag" "$arch" "$tmp"
build_kexec_bundle "$tag" "$arch" "$tmp" build_kexec_bundle "$tag" "$arch" "$tmp"
build_netboot_image "$tag" "$arch" "$tmp" build_netboot_image "$tag" "$arch" "$tmp"
) )

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@ -0,0 +1,77 @@
{ pkgs ? import <nixpkgs> {} }:
let
makeTest = import (pkgs.path + "/nixos/tests/make-test-python.nix");
makeTest' = args: makeTest args {
inherit pkgs;
inherit (pkgs) system;
};
in makeTest' {
name = "kexec-installer";
meta = with pkgs.lib.maintainers; {
maintainers = [ mic92 ];
};
nodes = {
node1 = { ... }: {
virtualisation.vlans = [ ];
virtualisation.memorySize = 4 * 1024;
virtualisation.diskSize = 4 * 1024;
virtualisation.useBootLoader = true;
virtualisation.useEFIBoot = true;
boot.loader.systemd-boot.enable = true;
boot.loader.efi.canTouchEfiVariables = true;
services.openssh.enable = true;
};
node2 = { pkgs, modulesPath, ... }: {
virtualisation.vlans = [ ];
environment.systemPackages = [ pkgs.hello ];
imports = [
./kexec-installer.nix
];
};
};
testScript = { nodes, ... }: ''
# Test whether reboot via kexec works.
node1.wait_for_unit("multi-user.target")
node1.succeed('kexec --load /run/current-system/kernel --initrd /run/current-system/initrd --command-line "$(</proc/cmdline)"')
node1.execute("systemctl kexec >&2 &", check_return=False)
node1.connected = False
node1.connect()
node1.wait_for_unit("multi-user.target")
# Check if the machine with netboot-minimal.nix profile boots up
node2.wait_for_unit("multi-user.target")
node2.shutdown()
node1.wait_for_unit("sshd.service")
host_ed25519_before = node1.succeed("cat /etc/ssh/ssh_host_ed25519_key.pub")
node1.succeed('ssh-keygen -t ed25519 -f /root/.ssh/id_ed25519 -q -N ""')
root_ed25519_before = node1.succeed('tee /root/.ssh/authorized_keys < /root/.ssh/id_ed25519.pub')
# Kexec node1 to the toplevel of node2 via the kexec-boot script
node1.succeed('touch /run/foo')
node1.fail('hello')
node1.succeed('mkdir -p /root/kexec')
node1.succeed('mkdir -p /root/kexec')
node1.succeed('tar -xf ${nodes.node2.config.system.build.kexecTarball}/tarball/nixos-kexec-installer-${pkgs.system}.tar.xz -C /root/kexec')
node1.execute('/root/kexec/kexec-boot')
# wait for machine to kexec
node1.execute('sleep 9999', check_return=False)
node1.succeed('! test -e /run/foo')
node1.succeed('hello')
node1.succeed('[ "$(hostname)" = "node2" ]')
node1.wait_for_unit("sshd.service")
host_ed25519_after = node1.succeed("cat /etc/ssh/ssh_host_ed25519_key.pub")
assert host_ed25519_before == host_ed25519_after, f"{host_ed25519_before} != {host_ed25519_after}"
root_ed25519_after = node1.succeed("cat /root/.ssh/authorized_keys")
assert root_ed25519_before == root_ed25519_after, f"{root_ed25519_before} != {root_ed25519_after}"
node1.shutdown()
'';
}

89
nix/kexec-installer.nix Normal file
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@ -0,0 +1,89 @@
{ config, lib, modulesPath, pkgs, ... }:
{
imports = [
(modulesPath + "/installer/netboot/netboot-minimal.nix")
];
# We are stateless, so just default to latest.
system.stateVersion = config.system.nixos.version;
# This is a variant of the upstream kexecScript that also allows embedding
# a ssh key.
system.build.kexecBoot = lib.mkForce (pkgs.writeScript "kexec-boot" ''
#!/usr/bin/env bash
set -ex
shopt -s nullglob
SCRIPT_DIR=$( cd -- "$( dirname -- "''${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
INITRD_TMP=$(mktemp -d)
cd "$INITRD_TMP"
pwd
mkdir initrd initrd/ssh
pushd initrd
if [ -e /root/.ssh/authorized_keys ]; then
cat /root/.ssh/authorized_keys >> ssh/authorized_keys
fi
if [ -e /etc/ssh/authorized_keys.d/root ]; then
cat /etc/ssh/authorized_keys.d/root >> ssh/authorized_keys
fi
for p in /etc/ssh/ssh_host_*; do
cp -a "$p" ssh
done
find -type f | cpio -o -H newc | gzip -9 > ../extra.gz
popd
cat "''${SCRIPT_DIR}/initrd.gz" extra.gz > final.gz
"$SCRIPT_DIR/kexec" --load "''${SCRIPT_DIR}/bzImage" \
--initrd=final.gz \
--command-line "init=${config.system.build.toplevel}/init ${toString config.boot.kernelParams}"
# kexec will map the new kernel in memory so we can remove the kernel at this point
rm -r "$INITRD_TMP"
# Disconnect our background kexec from the terminal
if [[ -e /dev/kmsg ]]; then
# this makes logging visible in `dmesg`, or the system consol or tools like journald
exec > /dev/kmsg 2>&1
else
exec > /dev/null 2>&1
fi
# We will kexec in background so we can cleanly finish the script before the hosts go down.
# This makes integration with tools like terraform easier.
nohup bash -c "sleep 6 && '$SCRIPT_DIR/kexec' -e" &
'');
system.build.kexecTarball = pkgs.callPackage (pkgs.path + "/nixos/lib/make-system-tarball.nix") {
fileName = "nixos-kexec-installer-${pkgs.stdenv.hostPlatform.system}";
contents = [
{
target = "/initrd.gz";
source = "${config.system.build.netbootRamdisk}/initrd";
}
{
target = "/bzImage";
source = "${config.system.build.kernel}/${config.system.boot.loader.kernelFile}";
}
{
target = "/kexec-boot";
source = config.system.build.kexecBoot;
}
{
target = "/kexec";
source = "${pkgs.pkgsStatic.kexec-tools}/bin/kexec";
}
];
};
documentation.enable = false;
# Not really needed. Saves a few bytes and the only service we are running is sshd, which we want to be reachable.
networking.firewall.enable = false;
# Restore ssh host and user keys if they are available.
# This avoids warnings of unknown ssh keys.
boot.initrd.postMountCommands = ''
mkdir -p /mnt-root/etc/ssh /mnt-root/root/.ssh
if [[ -f /ssh/authorized_keys ]]; then
cp ssh/authorized_keys /mnt-root/root/.ssh/
fi
cp ssh/ssh_host_* /mnt-root/etc/ssh
'';
}