misc_nixos-mailserver/mail-server/post-upgrade-check.nix

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# nixos-mailserver: a simple mail server
# Copyright (C) 2016-2018 Robin Raymond
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>
{ config, pkgs, lib, ... }:
with lib;
let
cfg = config.mailserver;
in
{
config = mkIf (cfg.enable && cfg.rebootAfterKernelUpgrade.enable) {
systemd.services.nixos-upgrade.serviceConfig.ExecStartPost = pkgs.writeScript "post-upgrade-check" ''
#!${pkgs.stdenv.shell}
# Checks whether the "current" kernel is different from the booted kernel
# and then triggers a reboot so that the "current" kernel will be the booted one.
# This is just an educated guess. If the links do not differ the kernels might still be different, according to spacefrogg in #nixos.
current=$(readlink -f /run/current-system/kernel)
booted=$(readlink -f /run/booted-system/kernel)
if [ "$current" == "$booted" ]; then
echo "kernel version seems unchanged, skipping reboot" | systemd-cat --priority 4 --identifier "post-upgrade-check";
else
echo "kernel path changed, possibly a new version" | systemd-cat --priority 2 --identifier "post-upgrade-check"
echo "$booted" | systemd-cat --priority 2 --identifier "post-upgrade-kernel-check"
echo "$current" | systemd-cat --priority 2 --identifier "post-upgrade-kernel-check"
${cfg.rebootAfterKernelUpgrade.method}
fi
'';
};
}