104 lines
2.8 KiB
Nix
104 lines
2.8 KiB
Nix
# Defines a service for automatically and periodically calling depot's
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# rebuild-system on a NixOS machine.
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#
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# Deploys can be stopped in emergency situations by creating an empty
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# file called `stop` in the state directory of the auto-deploy service
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# (typically /var/lib/auto-deploy).
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{ depot, config, lib, pkgs, ... }:
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let
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cfg = config.services.depot.auto-deploy;
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description = "to automatically rebuild the current system's NixOS config from the latest checkout of depot";
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rebuild-system = depot.ops.nixos.rebuildSystemWith "$STATE_DIRECTORY/deploy";
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deployScript = pkgs.writeShellScript "auto-deploy" ''
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set -ueo pipefail
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if [[ $EUID -ne 0 ]]; then
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echo "Oh no! Only root is allowed to run auto-deploy!" >&2
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exit 1
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fi
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if [[ -f $STATE_DIRECTORY/stop ]]; then
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echo "stop file exists in $STATE_DIRECTORY, not deploying!" >&2
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exit 1
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fi
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readonly depot=$STATE_DIRECTORY/depot.git
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readonly deploy=$STATE_DIRECTORY/deploy
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readonly git="git -C $depot"
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# find-or-create depot
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if [ ! -d $depot ]; then
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# cannot use $git here because $depot doesn't exist
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git clone --bare ${cfg.git-remote} $depot
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fi
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function cleanup() {
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$git worktree remove $deploy
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}
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trap cleanup EXIT
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$git fetch origin
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$git worktree add --force $deploy FETCH_HEAD
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# unsure why, but without this switch-to-configuration attempts to install
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# NixOS in $STATE_DIRECTORY
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(cd / && ${rebuild-system}/bin/rebuild-system)
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'';
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in
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{
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options.services.depot.auto-deploy = {
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enable = lib.mkEnableOption description;
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git-remote = lib.mkOption {
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type = lib.types.str;
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default = "https://cl.tvl.fyi/depot.git";
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description = ''
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The (possibly remote) repository from which to clone as specified by the
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GIT URLS section of `man git-clone`.
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'';
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};
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interval = lib.mkOption {
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type = lib.types.str;
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example = "1h";
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description = ''
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Interval between Nix builds, specified in systemd.time(7) format.
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'';
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};
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};
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config = lib.mkIf cfg.enable {
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systemd.services.auto-deploy = {
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inherit description;
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script = "${deployScript}";
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path = with pkgs; [
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bash
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git
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gnutar
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gzip
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];
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after = [ "network-online.target" ];
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wants = [ "network-online.target" ];
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# We need to prevent NixOS from interrupting us while it attempts to
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# restart systemd units.
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restartIfChanged = false;
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serviceConfig = {
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Type = "oneshot";
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StateDirectory = "auto-deploy";
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};
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};
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systemd.timers.auto-deploy = {
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inherit description;
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wantedBy = [ "multi-user.target" ];
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timerConfig = {
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OnActiveSec = "1";
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OnUnitActiveSec = cfg.interval;
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};
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};
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};
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}
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