depot/hosts/deploy.nix

{ config, inputs, lib, self, withSystem, ... }:

let
  inherit (lib) const elem flip genAttrs mapAttrs;
  inherit (config) gods defaultEffectSystem systems;
  inherit (self) nixosConfigurations;

  chosenHours = gods.fromLight;

  withEffectSystem = withSystem defaultEffectSystem;

  callUpon = hours: mapAttrs (hour: const nixosConfigurations.${hour}.config.system.build.toplevel) hours;
in

{
  herculesCI = { config, ... }: {
    onPush.default.outputs.effects.callUponTheHours = withEffectSystem ({  hci-effects, ... }: let
      inherit (hci-effects) runIf runCachixDeploy;
    in runIf (elem config.repo.branch [ "master" "staging" ]) (
      runCachixDeploy {
        async = true;
        deploy = {
          agents = callUpon chosenHours;
          rollbackScript = genAttrs systems (flip withSystem ({ pkgs, ... }:
            let
              scheduleReboot = pkgs.writeShellScript "schedule-reboot.sh" ''
                currentTime=$(date +%s)
                lastScheduledTime=$(consul kv get system/coordinated-reboot/last)
                if [[ $? -ne 0 ]]; then
                  lastScheduledTime=$((currentTime - 300))
                fi
                nextScheduledTime=$((lastScheduledTime + 900))
                if [[ $nextScheduledTime -lt $((currentTime + 300)) ]]; then
                  nextScheduledTime=$((currentTime + 300))
                fi
                consul kv put system/coordinated-reboot/last $nextScheduledTime
                echo "Scheduling reboot for $nextScheduledTime"
                systemd-analyze timestamp @$nextScheduledTime
                busctl call \
                  org.freedesktop.login1 \
                  /org/freedesktop/login1 \
                  org.freedesktop.login1.Manager \
                  ScheduleShutdown st reboot ''${nextScheduledTime}000000
              '';
            in pkgs.writeShellScript "post-effect.sh" ''
              export PATH="${pkgs.consul}/bin:${pkgs.coreutils}/bin"
              if [[ "$(realpath /run/booted-system/kernel)" != "$(realpath /run/current-system/kernel)" ]]; then
                echo "Scheduling reboot for kernel upgrade"
                if ! consul members >/dev/null; then
                  echo "Consul not active, skipping reboot"
                  exit 0
                fi
                consul lock --timeout=3m system/coordinated-reboot ${scheduleReboot}
              fi
            ''
          ));
        };
      }
    ));
  };
}