{ makeSystem
, nixpkgs
, hydra
}:
makeSystem {
  system = "x86_64-linux";
  name = "nixng-hydra";
  inherit nixpkgs;
  config = { pkgs, config, lib, nglib, ... }:
    {
      config = {
        dumb-init = {
          enable = true;
          type.services = {};
        };
        nix = {
          package = pkgs.nixUnstable;
          loadNixDb = true;
          persistNix = "/nix-persist";
          config = {
            experimental-features = [ "nix-command" "flakes" ];
            sandbox = true;
            trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
            substituters = [ "https://cache.nixos.org/" ];
            ignored-acls = [ "system.nfs4_acl" ];
            allowed-uris = [
              "https://gitea.redalder.org"
              "https://github.com"
              "https://gitlab.com"
              "https://git.sr.ht"
              "https://raw.githubusercontent.com"
              "https://media.forgecdn.net"
            ];

            builders-use-substitutes = true;
            builders = "@/etc/nix/machines";
          };
        };
        services.hydra = {
          enable = true;
          package = hydra.packages.x86_64-linux.hydra;
          hydraURL = "https://hydra.redalder.org";
          notificationSender = "hydra@redalder.org";
          useSubstitutes = true;
          adjustNiceness = true;

          minimumDiskFree = 200;
          minimumDiskFreeEvaluator = 100;

          dbiFile = "/local/dbi";
          config.evaluator_max_memory_size = "2048M";
        };
        services.socklog = {
          enable = true;
          unix = "/dev/log";
        };

        init.services.pgpass = {
          script = pkgs.writeShellScript "pgpass" ''
              ln -nsf /secrets/pgpass /var/lib/hydra/pgpass
              ln -nsf /secrets/pgpass-www /var/lib/hydra/pgpass-www
              ln -nsf /secrets/pgpass-queue-runner /var/lib/hydra/pgpass-queue-runner

              chown hydra:hydra /secrets/pgpass
              chown hydra-www:hydra /secrets/pgpass-www
              chown hydra-queue-runner:hydra /secrets/pgpass-queue-runner
              sv down pgpass
            '';
          enabled = true;
        };

        services.crond.crontabs.autogc = {
          jobs =
            let
              storegc = pkgs.writeShellScript "storegc"
                ''
                  nix-collect-garbage -d
                '';
            in
              [
                "0 4 * * * ${storegc}"
              ];
        };

        init.services.nix-daemon.environment.PATH = with pkgs;  lib.makeBinPath [
          utillinux
          runit
          busybox
          openssh
          gzip
        ];

        system.activation =
          let
            machines = pkgs.writeText "machines" ''
              eu.nixbuild.net x86_64-linux - 100 5 benchmark,big-parallel
            '';
            nix-machines = nglib.dag.dagEntryAnywhere ''
              export PATH=${pkgs.busybox}/bin

              mkdir -p /etc/nix
              ln -s ${machines} /etc/nix/machines
            '';

            ssh_config = pkgs.writeText "ssh_config" ''
              Host eu.nixbuild.net
                PubkeyAcceptedKeyTypes ssh-ed25519
                IdentityFile /ssh-key
            '';
            ssh_known_hosts = pkgs.writeText "ssh_known_hosts" ''
              eu.nixbuild.net ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPIQCZc54poJ8vqawd8TraNryQeJnvH1eLpIDgbiqymM
            '';
            ssh = nglib.dag.dagEntryAnywhere ''
              export PATH=${pkgs.busybox}/bin

              mkdir -p /etc/ssh
              ln -s ${ssh_config} /etc/ssh/ssh_config
              ln -s ${ssh_known_hosts} /etc/ssh/ssh_known_hosts
            '';

            ssh-key = nglib.dag.dagEntryAfter ["users"] ''
              export PATH=${pkgs.busybox}/bin

              cp /secrets/ssh-key /ssh-key
              chmod 600 /ssh-key
              chown hydra-queue-runner:root /ssh-key
            '';
          in
            {
              inherit ssh-key ssh nix-machines;
            };
      };
    };
}